Papers for Thursday, Oct 10 2024

Gravito-inertial asteroseismology saw its birth from the 4-years long light curves of rotating main-sequence stars assembled by the Kepler space telescope. High-precision measurements of internal rotation and mixing are available for about 600 stars of intermediate mass so far that are used to challenge the state-of-the-art stellar structure and evolution models. Our aim is to prepare for future large ensemble modelling of gravity (g)-mode pulsators by relying on a new sample of such stars recently discovered from the third Data Release of the Gaia space mission and confirmed by space photometry from the TESS mission. This sample of potential asteroseismic targets is about 23 times larger than the Kepler sample. We use the effective temperature and luminosity inferred from Gaia to deduce evolutionary masses, convective core masses, radii, and ages for ~14,000 g-mode pulsators classified as such from their nominal TESS light curves. We do so by constructing two dedicated grids of evolutionary models for rotating stars with input physics from the asteroseismic calibrations of Kepler $\gamma$ Dor pulsators. We find the new g-mode pulsators to cover an extended observational instability region covering masses from about 1.3 to 9Msun. We provide their mass-luminosity and mass-radius relations, as well as convective core masses. Our results suggest that oscillations excited by the opacity mechanism occur uninterruptedly for the mass range above about 2Msun, where stars have a radiative envelope aside from thin convection zones in their excitation layers. Our evolutionary parameters for the sample of Gaia-discovered g-mode pulsators with confirmed modes by TESS offer a fruitful starting point for future TESS ensemble asteroseismology once a sufficient number of modes is identified in terms of the geometrical wave numbers and overtone for each of the pulsators.

Dual active galactic nuclei (AGN) offer a unique opportunity to probe the relationship between super massive black holes (SMBH) and their host galaxies as well as the role of major mergers in triggering AGN activity. The confirmed dual AGN Mrk 266 has been studied extensively with multi-wavelength imaging. Now, high spatial resolution IFU spectroscopy of Mrk 266 provides an opportunity to probe the kinematics of both the merger event and AGN feedback. We present for the first time high spatial resolution kinematic maps for both nuclei of Mrk 266 obtained with the Keck OSIRIS IFU spectrograph, utilizing adaptive optics to achieve a resolution of 0.31" and 0.20" for the NE and SW nuclei, respectively. Using the M-sigma relation for mergers, we infer a SMBH mass of approximately 7e7 solar masses for the southwestern nucleus. Additionally, we report that the molecular gas kinematics of the southwestern nucleus are dominated by rotation rather than large-scale chaotic motions. The southwest nucleus also contains both a circumnuclear ring of star formation from which an inflow of molecular gas is likely fueling the AGN and a compact, AGN-dominated outflow of highly ionized gas with a timescale of approximately 2 Myr, significantly shorter than the timescale of the merger. The northeastern nucleus, on the other hand, exhibits complex kinematics related to the merger, including molecular gas that appears to have decoupled from the rotation of the stars. Our results suggest that while the AGN activity in Mrk 266 was likely triggered during the merger, AGN feeding is currently the result of processes internal to each host galaxy, thus resulting in a strong asymmetry between the two nuclei.

Recent observations and analyses of absorption in quasar spectra suggest a rapid drop in the mean free path (MFP) at the late stage of reionization at $z\sim6$. We use the Cosmic Reionization on Computers simulation to examine potential biases in observed measurements of the MFP at the late stage of reionization, particularly in the presence of a quasar. We analyze three snapshots surrounding the `ankle' point of reionization history, when extended neutral patches of the intergalactic medium disappeared in the simulation box. Specifically, these are $z=6.8$ (true MFP $\approx 0.4$~pMpc), in addition to $z=6.1$ (true MFP $\approx 2$~pMpc) and $z=5.4$ (true MFP $\approx 6$~pMpc). We compare the inferred MFP $\lambda_{\rm mfp}$ from synthetic spectra fits to the true MFP. We find that the mean Lyman continuum (LyC) profile at $z=6.8$ changes significantly with quasar lifetime $t_Q$. We attribute this sensitivity to $t_Q$ to a combination of extended neutral IGM patches and the prevalence of small-scale dense clumps. Consequently, the inferred MFP can be biased by a factor of few depending on $t_Q$. On the other hand, for the $z=6.1$ and $z=5.4$ snapshots, the mean LyC profile shows minimal sensitivity to variation in $t_Q\gtrsim 1$ Myr. The inferred MFP in these two cases is accurate to the $\lesssim 30\%$ level. Our results highlight how modeling systematics can affect the inferred MFP, particularly in the regime of small true MFP ($\lesssim 0.5$ pMpc). We also discuss the potential of this regime to provide a testing ground for constraining quasar lifetimes from LyC profiles.

We use Gaia DR3 to explore how well equilibrium dynamical models based on the Jeans equations and the Schwarzschild orbit superposition method are able to describe LMC's 5-dimensional phase-space distribution and line-of-sight (LOS) velocity distribution, respectively. In the latter model we incorporate a triaxial bar component and derive LMC's bar pattern speed. We fit Jeans dynamical models to all Gaia DR3 stars with proper motion and LOS velocity measurements found in the VMC VISTA survey of the LMC using a discrete maximum likelihood approach. These models are very efficient at discriminating genuine LMC member stars from Milky Way foreground stars and background galaxies. They constrain the shape, orientation, and enclosed mass of the galaxy under the assumption for axisymmetry. We use the Jeans model results as a stepping stone to more complex 2-component Schwarzschild models, which include an axisymmetric disc and a co-centric triaxial bar, which we fit to the LMC Gaia DR3 LOS velocity field, using a chi^2 minimisation approach. The Jeans models describe well the rotation and velocity dispersion of the LMC disc and we find an inclination angle 25.5 deg, line of nodes orientation 124 deg, and an intrinsic thickness of the disc 0.23 (minor to major axis ratio). However, bound to axisymmetry, these models fail to properly describe the kinematics in the central region of the galaxy, dominated by the bar. We use the derived disc orientation and the Gaia DR3 density image of the LMC to obtain the intrinsic shape of the bar. Using these two components as an input to our Schwarzschild models, we perform orbit integration and weighting in a rotating reference frame fixed to the bar, deriving an independent measurement of the LMC bar pattern speed 11+/-4 km/s/kpc. Both the Jeans and Schwarzschild models predict the same enclosed mass distribution within a radius of 6.2 kpc of ~1.4e10 Msun.

The stellar mass-star formation rate (M$_\star$ - SFR) plane is essential for distinguishing galaxy populations, but how galaxies move within this plane over cosmic time remains unclear. This study aims to describe galaxy migrations in the M$_\star$ - SFR plane by reconstructing star formation histories (SFHs) for a sample of galaxies out to redshift $z < 4$. This provides insights into the physical processes driving star formation. We use data from the COSMOS field, selecting 299131 galaxies at $z < 4$ with COSMOS-Web NIRCam data (m$_\mathrm{F444W} < 27$) over 0.54 deg$^2$. Using the SED modeling code CIGALE with non-parametric SFHs, we derive physical properties and migration vectors for these galaxies. These vectors describe the direction and velocity of evolutionary paths across the M$_\star$ - SFR plane. To assess the accuracy of these vectors, we compare them to results from the Horizon-AGN simulation. Galaxies within the main sequence show low migration amplitudes and dispersed movement directions, indicating oscillation within the main sequence. Most progenitors were already on the main sequence a billion years earlier. Starburst galaxies assembled half their mass in the last 350 Myr and originated from the main sequence. Passive galaxies show uniformly declining SFHs and include massive galaxies already in the passive region at $z = 3.5-4$, with increasing density over time. Using reconstructed SFHs up to $z < 4$, we propose a coherent picture of how galaxies migrate over cosmic time in the M$_\star$ - SFR plane, highlighting the connection between major phases in the star-formation history.

Feedback from active galactic nuclei (AGN) plays a critical role in shaping the matter distribution on scales comparable to and larger than individual galaxies. Upcoming surveys such as $\textit{Euclid}$ and LSST aim to precisely quantify the matter distribution on cosmological scales, making a detailed understanding of AGN feedback effects essential. Hydrodynamical simulations provide an informative framework for studying these effects, in particular by allowing us to vary the parameters that determine the strength of these feedback processes and, consequently, to predict their corresponding impact on the large-scale matter distribution. We use the EAGLE simulations to explore how changes in subgrid viscosity and AGN heating temperature affect the matter distribution, quantified via 2- and 3-point correlation functions, as well as higher order cumulants of the matter distribution. We find that varying viscosity has a small impact ($\approx 10\%$) on scales larger than $1 h^{-1}$ Mpc, while changes to the AGN heating temperature lead to substantial differences, with up to $70\%$ variation in gas clustering on small scales ($\lesssim 1 h^{-1}$ Mpc). By examining the suppression of the power spectrum as a function of time, we identify the redshift range $z = 1.5 - 1$ as a key epoch where AGN feedback begins to dominate in these simulations. The 3-point function provides complementary insight to the more familiar 2-point statistics, and shows more pronounced variations between models on the scale of individual haloes. On the other hand, we find that effects on even larger scales are largely comparable.

We present a detailed analysis of JWST/NIRSpec and NIRCam observations of ZF-UDS-7329, a massive, quiescent galaxy at redshift $z=3.2$, which has been put forward to challenge cosmology and galaxy formation physics. Our study extends previous works by focusing on the impact of different star formation history (SFH) priors, stellar libraries, metallicity, and initial mass function assumptions. Our results show that ZF-UDS-7329, with a formed stellar mass of $M_{\star} \approx 10^{11.4}~M_{\odot}$ and a specific star formation rate of $\mathrm{sSFR} \approx 0.03$ Gyr$^{-1}$, formed efficiently in the first billion years of the Universe. In agreement with previous work, we find that the spectrum is consistent with mass-weighted stellar ages of $1.3-1.8$ Gyr, depending on the SFH prior used. A physically motivated rising SFH prior makes the formation history of ZF-UDS-7329 compatible with stellar mass and star-formation rate estimates of high-redshift ($z>6$) galaxies. Using NIRCam imaging, we identify a colour gradient indicative of an old, quiescent bulge and a younger disc component, as expected from a complex formation history. The inferred SFH is consistent a high stellar fraction of $f_{\star}=M_{\star}/(f_b \cdot M_{\rm h}) \approx 100\%$ at $z=7-12$, implying an extremely high integrated star-formation efficiency. However, when considering cosmic variance and possible mergers as expected in over-dense environments - as traced by ZF-UDS-7329 - the stellar fractions could be reduced to $f_{\star} \approx 50\%$, which is more consistent with galaxy formation models and the stellar-to-halo mass relation at lower redshifts. We conclude that ZF-UDS-7329 forms extremely efficient in the early universe, but does not necessitate unseen galaxies at higher redshifts since the inferred SFR of ancestors are consistent with those seen in $z>6$ galaxies.

We study the effects of AGN feedback on the Lyman-$\alpha$ forest 1D flux power spectrum (P1D). Using the Simba cosmological-hydrodynamic simulations, we examine the impact that adding different AGN feedback modes has on the predicted P1D. We find that, for Simba, the impact of AGN feedback is most dramatic at lower redshifts ($z<1$) and that AGN jet feedback plays the most significant role in altering the P1D. The effects of AGN feedback can be seen across a large range of wavenumbers ($1.5\times10^{-3}<k<10^{-1}$ s/km) changing the ionization state of hydrogen in the IGM through heating. AGN feedback can also alter the thermal evolution of the IGM and thermally broaden individual Lyman-$\alpha$ absorbers. For the Simba model, these effects become observable at $z \lesssim 1.0$. At higher redshifts ($z>2.0$), AGN feedback has a $2\%$ effect on the P1D for $k<5\times10^{-2}$ s/km and an $8\%$ effect for $k>5\times10^{-2}$ s/km. We show that the small scale effect is reduced when normalizing the simulation to the observed mean flux. On large scales, the effect of AGN feedback appears via a change in the IGM temperature and is thus unlikely to bias cosmological parameters. The strong AGN jets in the Simba simulation can reproduce the $z>2$ Lyman-$\alpha$ forest. We stress that analyses comparing different AGN feedback models to future higher precision data will be necessary to determine the full extent of this effect.

Context. Green valley (GV) galaxies are objects defined on a color-magnitude, or color-mass, diagram which are associated with a transition from a star-forming to a quiescent state (quenching), or vice versa (rejuvenation). Aims. We study the sub-mm emission of galaxies in the GV and link it with their physical evolutionary properties. Methods. We exploit a semi-analytic model (SAM) for galaxy evolution which includes a detailed treatment of dust production and evolution in galactic contexts. We model the observational properties of simulated galaxies by post-processing the SAM catalogs with the spectral synthesis and radiative transfer code GRASIL. Results. Our model produces a clear bimodality (and thus a GV) in the color-mass diagram, although some tensions arise when compared to observations. After having introduced a new criterion for identifying the GV in any dataset, we find that most blue and GV galaxies in our model are emitters at $250\,{\mu \rm m}$ (with fluxes $\geq 25\,{\rm mJy}$), in keeping with GAMA results. In the color-$S_{250\, \mu \rm m}$ diagram, GV galaxies exhibit intermediate colors yet maintain significant sub-mm fluxes. This occurs because, while specific star formation rates drop sharply during quenching, the dust content remains relatively high during the GV transition, powering sub-mm emission. Rejuvenating galaxies in the GV, which were previously red, have experienced a star formation burst that shifts their color to green, but their $S_{250\, \mu \rm m}$ fluxes remain low due to still low dust mass. Conclusions. Our galaxy evolution model highlights the delay between star formation and dust evolution, showing that sub-mm emission is not always a safe indicator of star formation activity, with quenching (rejuvenating) GV galaxies featuring relatively large (low) sub-mm emission.

The origins of the magnetic fields that power gamma-ray burst (GRB) afterglow emission are not fully understood. One possible channel for generating these fields involves the pre-conditioning of the circumburst medium: in the early afterglow phase, prompt photons streaming ahead of the GRB external shock can pair produce, seeding the upstream with drifting electron-positron pairs and triggering electromagnetic microinstabilities. To study this process, we employ 2D periodic particle-in-cell simulations in which a cold electron-proton plasma is gradually enriched with warm electron-positron pairs injected at mildly relativistic speeds. We find that continuous pair injection drives the growth of large-scale magnetic fields via filamentation-like instabilities; the temporal evolution of the field is self-similar and depends on a single parameter, $\left[\alpha/(t_f \omega_{pi})\right]^{1/2} t\omega_{pi}$, where $\alpha$ is the ratio of final pair beam density to background plasma density, $t_f$ is the duration of pair injection, and $\omega_{pi}$ is the plasma frequency of background protons. Extrapolating our results to parameter regimes realistic for long GRBs, we find that upstream pair enrichment generates weak magnetic fields on scales much larger than the proton skin depth; for bright bursts, the extrapolated coherence scale at a shock radius of $R \sim 10^{17}$ cm is $\left<\lambda_y\right> \sim 100 c/\omega_{pi}$ and the corresponding magnetization is $\sigma \sim 10^{-8}$ for typical circumburst parameters. These results may help explain the persistence of magnetic fields at large distances behind GRB shocks.

We develop a novel framework for Large Scale Structure (LSS) perturbation theory, that solves the Vlasov-Poisson system of equations for the distribution function in full phase-space. This approach relaxes the usual apriori assumptions of negligible velocity dispersion and vorticity underlying the Standard Perturbation Theory (SPT). We apply the new method to rederive the usual SPT kernels up to third order in the perturbative expansion. We also show that a counterterm, identical to the one introduced by standard Effective Field Theory (EFT) methods, naturally arises within our framework. We finish by making a precise connection to EFT techniques, which reveals the necessity of the EFTofLSS to self-consistently model the long-wavelength fluid, and illustrates the importance of having theoretical control over short distance fluctuations.

Black hole - neutron star $(BH/NS)$ binaries are of interest in many ways: they are intrinsically multi-messenger systems, highly transient, radiate gravitational waves detectable by LIGO, and may produce $\gamma$-ray bursts. Although it has long been assumed that their late-stage orbital evolution is driven entirely by gravitational wave emission, we show here that in certain circumstances, mass transfer from the neutron star onto the black hole can both alter the binary's orbital evolution and significantly reduce the neutron star's mass when the fraction of its mass transferred per orbit is $\gtrsim 10^{-2}$, the neutron star's mass diminishes by order-unity, leading to mergers in which the neutron star mass is exceptionally small. The mass transfer creates a gas disk around the black hole ${\it before}$ merger that can be comparable in mass to the debris remaining after merger, i.e. $\sim 0.1 M_\odot$. These processes are most important when the initial neutron star/black hole mass ratio $q$ is in the range $\approx 0.2 - 0.8$, the orbital semimajor axis is $40 \lesssim a_0/r_g \lesssim 300 $ ($r_g \equiv GM_{\rm B}/c^2$), and the eccentricity is large, $e_0 \gtrsim 0.8$. Systems of this sort may be generated through the dynamical evolution of a triple system, as well as by other means.

The recent detection of optical emission lines from the circumgalactic medium (CGM) in combined, large samples of low-redshift, normal galaxy spectra hints at the potential to map the cool ($\sim$ 10$^4$ K) CGM in individual, representative galaxies. Using archival data from a forefront instrument (MUSE) on the VLT, we present a source-blind, wide-redshift-range ($z \sim 0-5)$ narrow-band imaging survey for CGM emission. Our detected, resolved emission line sources are cataloged and include a 30 kpc wide H$\alpha$ source likely tracing the CGM of a low-mass galaxy (stellar mass $\sim$ $10^{8.78\pm0.42}$ M$_\odot$) at $z=0.1723$, a 60 kpc wide Ly $\alpha$ structure associated with a galaxy at $z=3.9076$, and a 130 kpc ($\sim r_{\rm vir}$) wide [O II] feature revealing an interaction between a galaxy pair at $z=1.2480$. The H$\alpha$ velocity field for the low-mass galaxy suggests that the CGM is more chaotic or turbulent than the galaxy disk, while that for the interacting galaxies shows large-scale ($\sim 50$ kpc) coherent motions.

The first generation of stars (PopIII) are too dim to be observed directly and probably too short-lived to have survived for local observations. Hence, we rely on simulations and indirect observations to constrain the nature of the first stars. In this study, we calibrate the semi-analytical model A-SLOTH (Ancient Stars and Local Observables by Tracing Halos), designed for simulating star formation in the early Universe, using a likelihood function based on nine independent observables. These observables span Milky Way-specific and cosmologically representative variables, ensuring a comprehensive calibration process. This calibration methodology ensures that A-SLOTH provides a robust representation of the early Universe's star formation processes, aligning simulated values with observed benchmarks across a diverse set of parameters. The outcome of this calibration process is best-fit values and their uncertainties for 11 important parameters that describe star formation in the early Universe, such as the shape of the initial mass function (IMF) of PopIII stars or escape fractions of ionizing photons. Our best-fitting model has a PopIII IMF with a steeper slope, d$N$/d$M \propto M^{-1.77}$, than the log-flat models often proposed in the literature, and also relatively high minimum and maximum masses, $M_{\rm min} = 13.6$Msun and $M_{\rm max} = 197$Msun. However, we emphasize that the IMF-generating parameters are poorly constrained and, e.g., the IMF slope could vary from log-flat to Salpeter. We also provide data products, such as delay time distribution, bubble size distributions for ionizing and metal-enriched bubbles at high redshift, and correlation plots between all 11 input parameters. Our study contributes to understanding the formation of early stars through A-SLOTH and provides valuable insights into the intricate processes involved in the early Universe's star formation.

[Abridged]Ultra-faint dwarfs (UFDs) are expected to be the relics of the earliest galaxies forming in the Universe. Observations show the presence of a stellar halo around them, which can give precious insights into the evolution of UFDs. This work investigates how merger properties impact the formation of stellar halos around UFDs, focusing on Tucana II, the most promising UFD assembled through mergers. We develop N-body simulations of isolated mergers between two UFDs with $1M_\odot$ stellar resolution. We build a suite of simulations by varying: i) the merger mass ratio, $M_1/M_2$, the specific ii) kinetic energy, $k$, and iii) angular momentum, $l$, iv) the dark-to-stellar mass ratio, $M_{DM}/M_*$, of the progenitors and iv) their stellar size, $R_{1/2}$. We use a neural network to explore the parameter space, emulating the properties of the "post-merger" UFD by quantifying the half-mass radius ($R_*$) and the fraction of stars at radii $>5R_*$ ($f_5$). Our principal component analysis clearly shows that $f_5$ ($R_*$) is primarily determined by $M_1/M_2$ ($R_{1/2}$), with $R_{1/2}$ ($M_1/M_2$) playing a secondary role. Both $f_5$ and $R_*$ show almost no dependence on $k$, $l$, and $M_{DM}/M_*$ in the explored range. Using our emulator, we find that to form the stellar halo observed in Tucana II, i.e. $f_5=10\pm5\%$ and $R_*=120\pm30$pc, we need $M_1/M_2=8_{-3}^{+4}$ and $R_{1/2}=97^{+25}_{-18}$pc. Such findings are corroborated by the consistency ($\chi^2=0.5-2$) between the stellar density profile observed and those of simulations having $M_1/M_2$ and $R_{1/2}$ close to the emulator's predictions. Ongoing and planned spectroscopic surveys will greatly increase the statistics of observed stars and thus stellar halos in UFDs. By interpreting such observations with our model, we will provide new insights into the assembly history of UFDs and thus on the early galaxy formation process.

HIP 41378 f is a sub-Neptune exoplanet with an anomalously low density. Its long orbital period and deep transit make it an ideal candidate for detecting oblateness photometrically. We present a new cross-platform, GPU-enabled code greenlantern, suitable for computing transit light curves of oblate planets at arbitrary orientations. We then use Markov Chain Monte Carlo to fit K2 data of HIP 41378 b, d, and f, specifically examining HIP 41378 f for possible oblateness and obliquity. We find that the flattening of HIP 41378 f is $f \leq 0.18$ at the 95% confidence level, consistent with a rotation period of $P_\text{rot} \geq 22.2$ hr. In the future, high-precision data from JWST has the potential to tighten such a constraint and can differentiate between spherical and flattened planets.

We present a catalog of clouds identified from the $^{12}$CO (1--0) data of M83, which was observed using Atacama Large Millimeter/submillimeter Array (ALMA) with a spatial resolution of $\sim$46 pc and a mass sensitivity of $\sim$10$^4$ $M_{\odot}$ (3 $\sigma$). The almost full-disk coverage and high sensitivity of the data allowed us to sample 5724 molecular clouds with a median mass of $\sim1.9$ $\times$ $10^5$ $M_{\odot}$, which is comparable to the most frequently sampled mass of Giant Molecular Clouds by surveys in the Milky Way. About 60 percent of the total CO luminosity in M83's disk arises from clouds more massive than 10$^6$ $M_{\odot}$. Such massive clouds comprise 16 percent of the total clouds in number and tend to concentrate toward the arm, bar, and center, while smaller clouds are more prevalent in inter-arm regions. Most $>10^6$ $M_{\odot}$ clouds have peak brightness temperatures $T_{\mathrm{peak}}$ above 2 K with the current resolution. Comparing the observed cloud properties with the scaling relations determined by Solomon et al. 1987 (S87), $T_{\mathrm{peak}}$$>2$ K clouds follow the relations, but $T_{\mathrm{peak}}$$<2$ K clouds, which are dominant in number, deviate significantly. Without considering the effect of beam dilution, the deviations would suggest modestly high virial parameters and low surface mass densities for the entire cloud samples, which are similar to values found for the Milky Way clouds by Rice et al. (2016) and Miville-Desch{ê}nes et al. (2017). However, once beam dilution is taken into account, the observed $\alpha_{\mathrm{vir}}$ and $\Sigma$ for a majority of the clouds (mostly $T_{\mathrm{peak}}$ $<2$ K) can be potentially explained with intrinsic $\Sigma$ of $\sim$100 $M_{\mathrm{\odot}}\ \mathrm{pc}^{-2}$ and $\alpha_{\mathrm{vir}}$ of $\sim$1, which are similar to the clouds of S87.

Lunar ejecta, produced by meteoroidal impacts, have been proposed for the origin of the near-Earth asteroid (469219) Kamo'oalewa, supported by its unusually Earth-like orbit and L-type reflectance spectrum (Sharkey et al., 2021). In a recent study (Castro-Cisneros et al. 2023), we found with N-body numerical simulations that the orbit of Kamo'oalewa is dynamically compatible with rare pathways of lunar ejecta captured into Earth's co-orbital region, persistently transitioning between horseshoe and quasi-satellite (HS-QS) states. Subsequently, Jiao et al. (2024) found with hydrodynamic and N-body simulations that the geologically young lunar crater Giordano Bruno generated up to 300 Kamo'oalewa-sized escaping fragments, and up to three of those could have become Earth co-orbitals. However, these results are based upon specific initial conditions of the major planets in the Solar System, close to the current epoch. In particular, over megayear time spans, Earth's eccentricity undergoes excursions up to five times its current value, potentially affecting the chaotic orbital evolution of lunar ejecta and their capture into Earth's co-orbital regions. In the present work, we carry out additional numerical simulations to compute the statistics of co-orbital outcomes across different launch epochs, representative of the full range of Earth's eccentricity values. Our main results are as follows: Kamo'oalewa-like co-orbital outcomes of lunar ejecta vary only slightly across the range of Earth's orbital eccentricity, suggesting no privileged ejecta launching epoch for such objects; the probability of co-orbital outcomes decreases rapidly with increasing launch speed, but long-lived HS-QS states are favored at higher launch speeds.

We report the detection of broad, flat-topped emission in the fine-structure lines of [Ne V], [Ne VI], and [O IV] in mid-infrared spectra of the O9 V star 10 Lacertae obtained with JWST/MIRI. Optically thin emission in these high ions traces a hot, low-density component of the wind. The observed line fluxes imply a mass-loss rate of 2-4 x 10^8 Msun/yr, which is an order of magnitude larger than previous estimates based on UV and optical diagnostics. The presence of this hot component reconciles measured values of the mass-loss rate with theoretical predictions, and appears to solve the ``weak wind'' problem for the particular case of 10 Lac.

Planet-disk interactions can produce kinematic signatures in protoplanetary disks. While recent observations have detected non-Keplerian gas motions in disks, their origins are still being debated. To explore this, we conduct 3D hydrodynamic simulations using the code FARGO3D to study non-axisymmetric kinematic perturbations at 2 scale heights induced by Jovian planets in protoplanetary disks, followed by examinations of detectable signals in synthetic CO emission line observations at millimeter wavelengths. We advocate for using residual velocity or channel maps, generated by subtracting an azimuthally averaged background of the disk, to identify planet-induced kinematic perturbations. We investigate the effects of two basic simulation parameters, simulation duration and numerical resolution, on the simulation results. Our findings suggest that a short simulation (e.g., 100 orbits) is insufficient to establish a steady velocity pattern given our chosen viscosity ($\alpha=10^{-3}$), and displays plenty of fluctuations on orbital timescale. Such transient features could be detected in observations. By contrast, a long simulation (e.g., 1,000 orbits) is required to reach steady state in kinematic structures. At 1,000 orbits, the strongest and detectable velocity structures are found in the spiral wakes close to the planet. Through numerical convergence tests, we find hydrodynamics results converge in spiral regions at a resolution of 14 cells per disk scale height (CPH) or higher. Meanwhile, synthetic observations produced from hydrodynamic simulations at different resolutions are indistinguishable with 0.1$^{\prime\prime}$ angular resolution and 10 hours of integration time on ALMA.

EK Draconis, a nearby young solar-type star (G1.5V, 50-120 Myr), is known as one of the best proxies for inferring the environmental conditions of the young Sun. The star frequently produces superflares and Paper I presented the first evidence of an associated gigantic prominence eruption observed as a blueshifted H$\alpha$ Balmer line emission. In this paper, we present the results of dynamical modeling of the stellar eruption and examine its relationship to the surface starspots and large-scale magnetic fields observed concurrently with the event. By performing a one-dimensional free-fall dynamical model and a one dimensional hydrodynamic simulation of the flow along the expanding magnetic loop, we found that the prominence eruption likely occurred near the stellar limb (12$^{+5}_{-5}$-16$^{+7}_{-7}$ degrees from the limb) and was ejected at an angle of 15$^{+6}_{-5}$-24$^{+6}_{-6}$ degrees relative to the line of sight, and the magnetic structures can expand into a coronal mass ejection (CME). The observed prominence displayed a terminal velocity of $\sim$0 km s$^{-1}$ prior to disappearance, complicating the interpretation of its dynamics in Paper I. The models in this paper suggest that prominence's H$\alpha$ intensity diminishes at around or before its expected maximum height, explaining the puzzling time evolution in observations. The TESS light curve modeling and (Zeeman) Doppler Imaging revealed large mid-latitude spots with polarity inversion lines and one polar spot with dominant single polarity, all near the stellar limb during the eruption. This suggests that mid-latitude spots could be the source of the pre-existing gigantic prominence we reported in Paper I. These results provide valuable insights into the dynamic processes that likely influenced the environments of early Earth, Mars, Venus, and young exoplanets.

Recent studies revealed viewing-angle-dependent color and spectral trends in brown dwarfs, as well as long-term photometric variability (~100 hr). The origins of these trends are yet unexplained. Here, we propose that these seemingly unrelated sets of observations stem from the same phenomenon: The polar regions of brown dwarfs and directly imaged exoplanets are spectrally different from lower-latitude regions, and that they evolve over longer timescales, possibly driven by polar vortices. We explore this hypothesis via a spatio-temporal atmosphere model capable of simulating time-series, disk-integrated spectra of ultracool atmospheres. We study three scenarios with different spectral and temporal components: A null hypothesis without polar vortex, and two scenarios with polar vortices. We find that the scenarios with polar vortex can explain the observed infrared color-inclination trend and the variability amplitude-inclination trend. The presence of spectrally distinct, time-evolving polar regions in brown dwarfs and giant exoplanet atmospheres raises the possibility that one-dimensional, static atmospheric models may be insufficient for reproducing ultracool atmospheres in detail.

Ultra-High-Energy Cosmic Rays (UHECRs), particles characterized by energies exceeding $10^{18}$ eV, are generally believed to be accelerated electromagnetically in high-energy astrophysical sources. One promising mechanism of UHECR acceleration is magnetized turbulence. We demonstrate from first principles, using fully kinetic particle-in-cell simulations, that magnetically dominated turbulence accelerates particles on a short timescale, producing a power-law energy distribution with a rigidity-dependent, sharply defined cutoff well approximated by the form $f_{\rm cut}\left({E, E_{\rm cut}}\right) = {\text{sech}}\left[ ( {{E}/{E_{\rm cut}}} )^2 \right]$. Particle escape from the turbulent accelerating region is energy-dependent, with $t_{\rm esc} \propto E^{-\delta}$ and $\delta \sim 1/3$. The resulting particle flux from the accelerator follows $dN/dEdt \propto E^{-s} {\text{sech}}\left[ ( {{E}/{E_{\rm cut}}} )^2 \right]$, with $s \sim 2.1$. We fit the Pierre Auger Observatory's spectrum and composition measurements, taking into account particle interactions between acceleration and detection, and show that the turbulence-associated energy cutoff is well supported by the data, with the best-fitting spectral index being $s = 2.1^{+0.06}_{-0.13}$. Our first-principles results indicate that particle acceleration by magnetically dominated turbulence may constitute the physical mechanism responsible for UHECR acceleration.

Late-stage Ca-sulfate-filled fractures are common on Mars. Notably, the Shenandoah formation in the western edge of Jezero crater preserves a variety of Ca-sulfate minerals in the fine-grained siliciclastic rocks explored by the Perseverance rover. However, the depositional environment and timing of the formation of these sulfates is unknown. To address this outstanding problem, we developed a new technique to map the crystal textures of these sulfates in situ at two stratigraphically similar locations in the Shenandoah formation, allowing us to constrain the burial depth and paleoenvironment at the time of their deposition. Our results suggest that some Ca-sulfate analyzed was formed at a burial depth greater than 80m, whereas Ca-sulfates present at another outcrop likely precipitated in a shallow-subsurface environment. These results indicate that samples collected for potential return to Earth at the two studied locations capture two different times and distinct chemical conditions in the depositional history of the Shenandoah formation providing multiple opportunities to evaluate surface and subsurface habitability.

Polarization measurements provide insight into the magnetic field, a critical aspect of the dynamics and emission properties around the compact object. In this paper, we present the polarized magnetic field of the Crab outer torus and the Vela arc utilizing Imaging X-ray Polarimetry Explorer observation data. The polarization angle (PA) measured for the Crab outer torus exhibits two monotonic evolutions along the azimuth angle, which are consistent with the normal line of the elliptical ring. There is a slight increase in PA along the azimuth angle for both the inner arc and the outer arc of the Vela nebula. The polarized magnetic vector along the outer torus of the Crab nebula shows the polarized magnetic field aligns with Crab outer torus structure. The PA variation along the Crab outer torus suggests a bulk flow speed of 0.8c. Meanwhile, the Vela nebula polarized magnetic field does not exactly align with the Vela arc structure. We noted that the Crab nebula possesses a polarized toroidal magnetic field, where as the Vela nebula exhibits an incomplete toroidal magnetic field.

For many binary mixtures, the three-phase solid-liquid-vapor equilibrium curve has intermediate pressures that are higher than the pressure at the two pure triple points. This curve shape results in a negative slope in the high-temperature region near the triple point of the less volatile component. When freezing mixtures in the negative slope regime, fluid trapped below confined ice has latent heat released with more vapor upon cooling, and thus increases in pressure. If the rising pressure of the confined fluid overcomes the strength of the confining solid, which may be its own ice, it can produce an abrupt outburst of material and an increase in the system's overall pressure. Here, we report experimental results of freezing-induced outbursts occurring in the N2/CH4, CO/CH4, and N2/C2H6 systems, and provide insight into the phenomenon through a thermodynamics perspective. We also propose other binary systems that may experience outbursts and explore the geological implications for icy worlds like Titan, Triton, Pluto and Eris, as well as rocky bodies, specifically Earth and Mars.

Physical insight into plasma evolution in the magnetohydrodynamic (MHD) limit can be revealed by decomposing the evolution according to the characteristic modes of the system. In this paper we explore aspects of the eigenenergy decomposition method (EEDM) introduced in an earlier study (Raboonik et al. 2024 , ApJ, 967:80). The EEDM provides an exact decomposition of nonlinear MHD disturbances into their component eigenenergies associated with the slow, Alfvén, and fast eigenmodes, together with two zero-frequency eigenmodes. Here we refine the EEDM by presenting globally analytical expressions for the eigenenergies. We also explore the nature of the zero-frequency ``pseudo-advective modes'' in detail. We show that in evolutions with pure advection of magnetic and thermal energy (without propagating waves) a part of the energy is carried by the pseudo advective modes. Exact expressions for the error terms associated with these modes--commonly encountered in numerical simulations--are also introduced. The new EEDM equations provide a robust tool for the exact and unique decomposition of nonlinear disturbances governed by homogeneous quasi-linear partial differential equations, even in the presence of local or global degeneracies.

It has been suggested that Centaurus A (Cen A) could make a contribution to the observed ultrahigh-energy cosmic-ray (UHECR) flux. We calculate the flux of astrophysical neutrinos produced by UHECRs accelerated in the jet of Cen A, a close-by jetted active galactic nucleus. We use a bottom-up approach, in which we follow the energization of protons and heavier elements in a magnetohydrodynamic simulation of a relativistic jet with proper parameters of Cen A, also accounting for attenuation losses based on the observed photon fields. We compare the expected neutrino flux with the sensitivity of current and planned neutrino detectors. We find that the detection of $\sim 10^{17}$-$10^{18}$ eV neutrinos from Cen A would require ultimate neutrino detectors that reach a point source sensitivity of $\sim {\rm a~few}\times10^{-13}~{\rm erg}~{\rm cm}^{-2}~{\rm s}^{-1}$. Successful detection, though challenging, would be useful in constraining the Cen A contribution to the UHECRs.

We introduce a new capability of the Neil Gehrels Swift Observatory, dubbed `continuous commanding,' achieving 10 seconds latency response time on-orbit to unscheduled Target of Opportunity requests. This allows Swift to respond to early warning gravitational-wave detections, rapidly slewing the Burst Alert Telescope (BAT) across the sky to place the GW origin in the BAT field of view at merger time. This will dramatically increase the GW/GRB co-detection rate, and enable prompt arcminute localization of a neutron star merger. We simulate the full Swift response to a GW early warning alert, including input sky maps produced at different warning times, a complete model of Swift's attitude control system, and a full accounting of the latency between the GW detectors and the spacecraft. 60 s of early warning doubles the rate of prompt GRB detections with arcminute position, and 140 s guarantees observation anywhere on the unocculted sky, even with localization areas >> 1000 deg$^2$. While 140 s is beyond current gravitational wave detector sensitivities, 30-70 s is achievable today. We show that the detection yield is now limited by the latency of LIGO/Virgo cyber-infrastructure, and motivate focus on its reduction. Continuous commanding is now a general capability of Swift, significantly increasing its versatility in response to the growing demands of time-domain astrophysics. We demonstrate this potential on an externally triggered Fast Radio Burst, slewing 81 degrees across the sky, and collecting X-ray and UV photons from the source position < 150 s after the trigger was received from the Canadian Hydrogen Intensity Mapping Experiment (CHIME), thereby setting the earliest and deepest such constraints on high energy activity from non-repeating FRBs. The Swift Team invites proposals for novel scientific applications of ultra-low latency UV, X-ray, and gamma-ray observations.

Atmospheric compositions preserve the history of planet formation processes. Jupiter has the remarkable feature of being uniformly enriched in various elements compared to the Sun, including highly volatile elements such as nitrogen and noble gases. Radial transport of volatile species by amorphous ice in the solar nebula is one mechanism that explains Jupiter's volatile enrichment, but the low entrapment efficiency of nitrogen into amorphous ice is an issue. We propose an alternative mechanism of delivering nitrogen to Jupiter: radial transport of semi-volatile ammonium salts in the solar nebula. Ammonium salts have been identified in 67P/Churyumov-Gerasimenko and can potentially compensate for the comet's nitrogen depletion compared to the Sun. We simulate the radial transport and dissociation of ammonium salts carried by dust in a protoplanetary disk, followed by the accretion of the gas and NH$_3$ vapor by a protoplanet, as well as the delivery of nitrogen to the planetary atmosphere from the salt-containing planetary core that undergoes dilution. We find that when the dust contains 10-30 wt% ammonium salts, the production of NH$_3$ vapor in the inner disk (~ 3 au) by dissociated salts and the incorporation of the salt-derived NH$_3$ through core formation and subsequent gas accretion by the protoplanet result in a planetary nitrogen enrichment consistent with the observations of Jupiter. Ammonium salts may thus play a vital role in developing the atmospheric composition of planets forming in the inner disk. Combining our model with future observations of the bulk compositions and isotopes of comets and other primordial bodies will help to further elucidate the elemental transport to the gas giants and ice giants in the solar system.

We aim to trace the evolution of eight edge-on star-forming disc galaxies through the analysis of stellar population properties of their thin and thick discs. These galaxies have relatively low stellar masses (4 $\times$ 10$^9$ to 6 $\times$ 10$^{10}$ $M_{\odot}$). We use Multi-Unit Spectroscopic Explorer (MUSE) observations and full-spectrum fitting to produce spatially resolved maps of ages, metallicities and [Mg/Fe]-abundances and extract the star formation histories of stellar discs. Our maps show thick discs that are on average older, more metal-poor and more [Mg/Fe]-enhanced than thin discs. However, age differences between thin and thick discs are small (around 2 Gyr) and the thick discs are younger than previously observed in more massive and more quiescent galaxies. Both thin and thick discs show mostly sub-solar metallicities, and the vertical metallicity gradient is milder than previously observed in similar studies. [Mg/Fe] differences between thick and thin discs are not sharp. The star formation histories of thick discs extend down to recent times, although most of the mass in young stars was formed in thin discs. Our findings show thick discs that are different from old quiescent thick discs previously observed in galaxies of different morphologies and/or different masses. We propose that thick discs in these galaxies did not form quickly at high redshift, but slowly in an extended time. Also, the thin discs formed slowly, however, a larger mass fraction was created at very recent times.

OJ 287 is one of the most dynamic BL Lacertae objects that has exhibited behaviour representative of the entire blazar class and is also one of the best sources with simultaneous multi-wavelength coordinated data. Motivated by strong X-ray variability exhibited by the source, we systematically investigated the simultaneous optical to X-ray emission of the source with a focus on the spectral state of the lowest recorded X-ray flux state to understand the X-ray spectral changes. The optical-UV emission being synchrotron, the associated spectral variation is a direct reflection of the high-energy end of the underlying particle spectrum and its power-law continuation to X-rays can drastically affect the X-ray spectrum without much change in optical flux. Thus the combined optical to X-ray provides a potential tool to investigate and explore particle spectrum as well as highest particle energies. We report the finding of a power-law optical-UV spectrum with a photon spectral index of 2.71 $\pm$ 0.03 continuing to X-ray energies and accounting for this contribution at X-ray results in a photon spectral index of 1.15-1.3. We discuss the possible implications of this on X-ray spectral variations and the particle spectrum.

Observational cosmology is rapidly closing in on a measurement of the sum M_nu of neutrino masses, at least in the simplest cosmologies, while opening the door to probes of non-standard hot dark matter (HDM) models. By extending the method of effective distributions, we show that any collection of HDM species, with arbitrary masses, temperatures, and distribution functions, including massive neutrinos, may be represented as a single effective HDM species. Implementing this method in the FlowsForTheMasses non-linear perturbation theory for free-streaming particles, we study non-standard HDM models that contain thermal QCD axions or generic bosons in addition to standard neutrinos, as well as non-standard neutrino models wherein either the distribution function of the neutrinos or their temperature is changed. Along the way, we substantially improve the accuracy of this perturbation theory at low masses, bringing it into agreement with the high-resolution TianNu neutrino N-body simulation to about 2% at k = 0.1 h/Mpc and to within 21% up to k = 1 h/Mpc. We accurately reproduce the results of simulations including axions and neutrinos of multiple masses. Studying the differences between the normal, inverted, and degenerate neutrino mass orderings on their non-linear power, we quantify the error in the common approximation of degenerate masses. We release our code publicly at this http URL .

We generalise the SuperEasy linear response method, originally developed to describe massive neutrinos in cosmological $N$-body simulations, to any hot dark matter (HDM) species with arbitrary momentum distributions. The method uses analytical solutions of the HDM phase space perturbations in various limits and constructs from them a modification factor to the gravitational potential that tricks the cold particles into trajectories as if HDM particles were present in the simulation box. The modification factor is algebraic in the cosmological parameters and requires no fitting. Implementing the method in a Particle-Mesh simulation code and testing it on HDM cosmologies up to the equivalent effect of $\sum m_\nu = 0.315$ eV-mass neutrinos, we find that the generalised SuperEasy approach is able to predict the total matter and cold matter power spectra to $\lesssim 0.1\%$ relative to other linear response methods and to $\lesssim 0.25\%$ relative to particle HDM simulations. Applying the method to cosmologies with mixed neutrinos\Plus{}thermal QCD axions and neutrinos\Plus{}generic thermal bosons, we find that non-standard HDM cosmologies have no intrinsically different non-linear signature in the total matter power spectrum from standard neutrino cosmologies. However, because they predict different time dependencies even at the linear level and the differences are augmented by non-linear evolution, it remains a possibility that observations at multiple redshifts may help distinguish between them.

The outshining light from active galactic nuclei (AGNs) poses significant challenges in studying the properties of AGN host galaxies. To address this issue, we propose a novel approach which combines image decomposition and spectral energy distribution (SED) decomposition to constrain properties of AGN host galaxies. Image decomposition allows us to disentangle optical flux into AGN and stellar components, thereby providing additional constraints on the SED models to derive more refined stellar mass. To test the viability of this approach, we obtained a sample of 24 X-ray selected type-I AGNs with redshifts ranging from 0.73 to 2.47. We estimated the stellar masses for our sample and found that our results are generally consistent with earlier estimates based on different methods. Through examining the posterior distribution of stellar masses, we find that our method could derive better constrained results compared to previous SED decomposition methods. With the derived stellar masses, we further studied the $M_{\rm BH}-M_\star$ relation of our sample, finding a higher intrinsic scatter in the correlation for our entire sample compared to the local quiescent correlation, which could be caused by a few black hole monsters in our sample. We propose that based on our method, future works could extend to larger samples of high-redshift AGN host galaxies, thereby enhancing our understanding of their properties.

We aim to discern scenarios of structural evolution of intermediate to high-mass star-forming galaxies (SFGs) since cosmic noon by comparing their stellar mass profiles with present-day stellar masses of $\log(M_{\ast,0}/M_{\odot})=10.3-11$. We addressed discrepancies in the size evolution rates of SFGs, which may be caused by variations in sample selection and methods for size measurements. To check these factors, we traced the evolution of individual galaxies by identifying their progenitors using stellar mass growth histories (SMGHs), integrating along the star-forming main sequence and from the IllustrisTNG simulations. Comparison between the structural parameters estimated from the mass- and light-based profiles shows that mass-weighted size evolves at a slower pace compared to light-based ones, highlighting the need to consider the mass-to-light ratio ($M/L$) gradients. Additionally, we observed mass-dependent growth in stellar mass profiles: massive galaxies ($\log(M_{\ast,0}/M_{\odot})\gtrsim10.8$) formed central regions at $z\gtrsim1.5$ and grew faster in outer regions, suggesting inside-out growth, while intermediate and less massive SFGs followed a relatively self-similar mass buildup since $z\sim2$. Moreover, slopes of observed size evolution conflict with the predictions of TNG50 for samples selected using the same SMGHs across our redshift range. To explore the origin of this deviation, we examined changes in angular momentum (AM) retention fraction using the half-mass size evolution and employing a simple disk formation model. Assuming similar dark matter halo parameters, our calculations indicate that the AM inferred from observations halved in the last 10 Gyr while it remained relatively constant in TNG50. This higher AM in simulations may be due to the accretion of high-AM gases into disks.

The high redshift ($z>10$) galaxies GHZ9 and UHZ1 observed by the James Webb Space Telescope (JWST) are very massive and have exceptionally high black hole-to-star mass ratios with the central black hole masses $M\gtrsim 10^7\rm~M_\odot$. In this paper, we explore the possibility that they are seeded by the supermassive primordial black holes (SMPBHs), which came into being in the very early universe, with initial masses $\sim 10^7\rm~M_\odot$. We present the self-similar accretion solutions for SMPBHs, and find that the mass growth of SMPBHs during pregalactic era may be negligible. These SMPBHs, when the redshift $z\lesssim 20$, can accelerate seeding high-redshift galaxies and their baryonic content, and consequently explain the central supermassive black holes (SMBHs) of high-redshift massive galaxies through sub-Eddington accretion. According to our results, SMPBHs actually could lead to the existence of more massive SMBHs at higher redshifts compared to other SMBH seed scenarios, specially SMBHs with masses $M\gtrsim 10^7~\rm M_\odot$ at $z>20$ might only origin from SMPBHs, thus the corresponding observation can serve as a potential probe to PBHs.

Emission lines from complex organic molecules in B335 were observed in four epochs, spanning a luminosity burst of about 10 years duration. The emission lines increased dramatically in intensity as the luminosity increased, but they have decreased only slightly as the luminosity has decreased. This behavior agrees with expectations of rapid sublimation as the dust temperature increases, but slower freeze-out after the dust temperature drops. Further monitoring of this source, along with detailed chemical models, will exploit this natural laboratory for astrochemistry.

We introduce a novel method that utilizes the longitude-velocity (l-v) envelope to constrain the Milky Way (MW) bar potential. Previous work (Habing 2016) used the l-v diagram to explain the distribution of the observed high-velocity stars. We successfully reproduce their results, but find that their method is limited to only one single type of periodic orbits. In contrast, we propose that the l-v envelope provides much more comprehensive constraints. We compare the properties of test particles in the Portai et al. (2017) MW potential model (P17) with the observed SiO maser stars from the Bulge Asymmetries and Dynamical Evolution (BAaDE) survey. We find that the l-v envelope generated by the bar potential demonstrates reasonable agreement with the observational data, albeit with slight discrepancies near the Galactic center. The inconsistencies suggest that the P17 potential yields a lower central rotation curve, a slightly larger quadrupole strength, or a possibly underestimated pattern speed. We also adopt an updated version of the P17 potential with a modified central mass component (CMC) proposed by Hunter et al. (2024) (H24). The fitting of the l-v envelope suggests that the H24 potential does not completely address the existing challenges and may hint at a possible underestimation of the central bar mass. Our study demonstrates that the l-v envelope can be used as a valuable tool for constraining the Galactic potential and provides insights into the Milky Way bar potential.

A vertical metallicity gradient in the Milky Way bulge is well-established. Yet, its origin has not been fully understood under the Galactic secular evolution scenario. We construct single-disk and triple-disk $N$-body models with an initial radial metallicity gradient for each disk. These models generate a vertical metallicity gradient through a ``two-step heating" mechanism: first the outer, metal-poor particles move inward via the bar instability and subsequently undergo more significant vertical heating during the buckling instability, so they end up at greater vertical height. The ``two-step heating" mechanism nearly linearly transforms the radial metallicity gradients in precursor disks into vertical metallicity gradients. Comparing the models with a triple-disk model tagged with radially independent Gaussian metallicity, we find that, despite certain limitations, the ``two-step heating" mechanism is still important in shaping the Galactic vertical metallicity gradient. If the bar and buckling instabilities contributed to the formation of boxy/peanut-shaped bulges, then the ``two-step heating" mechanism is inevitable in the secular evolution of a boxy/peanut-shaped bulge.

Several pulsars with unusually long periods were discovered recently, comprising a potential population of ultra long period pulsars (ULPPs). The origin of their long periodicity is not well understood, but may be related to magnatars spun down by surrounding fallback disks. While there are few systematic investigations on the fallback disk-assisted evolution of magnetars, the instability in the disk has received little attention, which determines the lifetime of the disk. In this work we simulate the evolution of the magnetic field, spin period, and magnetic inclination angle of magnetars with a supernova fallback disk. We find that thermal viscous instability in the disk could significantly affect the formation of ULPPs. Our simulation results also reveal that a large fraction of ULPPs seem to be nearly aligned and orthogonal rotators. This might help place ULPPs above the death line in the pulse period - period derivative plane. However, some extra mechanisms seem to be required to account for radio emission of ULPPs.

In this paper, we show how baryonic physics can solve the problem of the striking diversity in dwarf galaxies rotation curves shapes. To this aim, we compare the distribution of galaxies of the SPARC sample, in the plane $V_{\rm 2 kpc}$-$V_{\rm Rlast }$ (being $V_{\rm 2kpc}$ the galaxy rotation velocity at $2$ kpc, and $V_{\rm Rlast}$ that outermost one) with that of galaxies that we simulated taking account of baryonic effects. The scatter in the rotation curves in the $V_{\rm 2 kpc}$-$V_{\rm Rlast }$ plane, and the trend of the SPARC sample's, and our simulated galaxies', distribution is in good agreement. The solution of the "diversity" problem lies in the ability of baryonic process to produce non self-similar haloes, contrary to DM-only simulations. We show also that baryonic effects can reproduce the rotation curves of galaxies like IC2574 characterized by a slow rising with radius. A solution to the diversity problem can be obtained taking appropriately into account the baryon physics effects.

Tellurium is a primary candidate for the identification of the 2.1 $\mu$m emission line in kilonovae (KNe) spectra AT2017gfo and GRB230307A. Despite this, there is currently an insufficient amount of atomic data available for this species. We calculate the required atomic structure and collisional data, particularly the data required for accurate Non-Local-Thermodynamic-Equilibrium (NLTE) modelling of the low temperatures and densities in KNe. We use a Multi-Configurational-Dirac-Hartree-Fock method to produce optimised one-electron orbitals for Te {\sc i}-{\sc iii}. As a result energy levels and Einstein A-coefficients for Te {\sc i}-{\sc iii} have been calculated. These orbitals are then employed within Dirac $R$-matrix collision calculations to provide electron-impact-excitation collision strengths that were subsequently averaged according to a thermal Maxwellian distribution. Subsequent \textsc{tardis} simulations using this new atomic data reveal no significant changes to the synthetic spectra due to the very minor contribution of Te at early epochs. NLTE simulations with the ColRadPy package reveal optically thin spectra consistent with the increasing prominence of the Te {\sc iii} 2.1 $\mu$m line as the KNe ejecta cools. This is reinforced by the estimation of luminosities at nebular KNe conditions. New line ratios for both observation and laboratory benchmarks of the atomic data are proposed.

The JAGB method is a new way of measuring distances with use of AGB stars that are situated in a selected region in a J versus J-Ks CMD, using the fact that the absolute J magnitude is (nearly) constant. It is implicitly assumed in the method that the selected stars are carbon-rich AGB stars. However, as the sample selected to determine M_J is purely colour based there can also be contamination by oxygen-rich AGB stars. As the ratio of C to O-rich stars is known to depend on metallicity and initial mass, the star formation history and age-metallicity relation in a galaxy should influence the value of M_J. The aim of this paper is to look at mixed samples of O- and C-rich stars for the LMC, the SMC and Milky Way (MW), using the Gaia catalogue of long period variables as basis. We report the mean and median magnitudes and the results of fitting Gaussian and Lorentzian profiles to the luminosity function (LF) using different colour and magnitudes cuts. For the SMC and LMC we confirm the previous results in the literature. The LFs of the SMC and LMC JAGB stars are clearly different, yet the mean magnitude inside a selection box can be argued to agree at the 0.02~mag level. The analysis of the MW sample is less straightforward. The contamination by O-rich stars is substantial for a classical lower limit of (J-Ks)0= 1.3, and becomes less than 10% only for (J-Ks)0= 1.5. The sample of AGB stars is much smaller than for the MCs for two reasons. Nearby AGB stars tend to be absent as they saturate in the 2MASS catalogue, and the parallax errors of AGB stars tend to be larger compared to non-AGB stars. The mean and median magnitudes are fainter than for the MC samples by about 0.4~mag which is not predicted by theory. We do not confirm the claim in the literature that the absolute calibration of the JAGB method is independent of metallicity up to solar metallicity.

This paper proposes new methods for analyzing dynamic images registered by multichannel, highly sensitive detectors with low spatial but high temporal resolution. The principal characteristic of the approach is the absence of factorization of different types of information within the data set. For a number of rapidly changing (transient) phenomena in the Earth's atmosphere, a probabilistic model can be formulated, and the parameters of this model can be reconstructed using probabilistic programming methods (Bayesian inference based on Markov chain Monte Carlo). This paper demonstrates the aforementioned approach on a number of examples, both simulated and actually registered by the detectors of the SINP MSU. In the case of submillisecond ELVES events registered by the orbital Mini-EUSO detector on board the ISS, the probabilistic model includes the coordinates and orientation of the lightning discharge that generated the glow, as well as the height of the ionized layer in which the glow is registered, among its parameters. Bayesian inference, implemented by means of the PyMC library, allows us to calculate posterior distributions for these parameters based on the times of signal peaks in individual detector channels. In addition to studying different types of aurora, the circumpolar system of ground-based multichannel PAIPS detectors also serves as a test-bench for probabilistic reconstruction algorithms. A wide class of track events is used for this purpose - meteors, satellite and aircraft passes, and the movement of stars across the sky. The Bayesian model includes both the parameters of the track event itself and the peculiarities of its registration. These methods can be generalized to stereo events (track registration by two detectors with overlapping fields of view) or applied to the reconstruction of extremely high energy cosmic rays in orbital fluorescence detectors.

We examine a new scenario to model the outer halo globular cluster (GC) Pal 14 over its lifetime by performing a comprehensive set of direct N-body calculations. We assume Pal 14 was born in a now detached/disrupted dwarf galaxy with a strong tidal field. Pal 14 evolved there until the slope of the stellar mass function (MF) became close to the measured value which is observed to be significantly shallower than in most GCs. After about 2-3 Gyr, Pal 14 was then captured by the Milky Way (MW). Although the physical size of such a cluster is indistinguishable from a cluster that has lived its entire life in the MW, other parameters like its mass and the MF-slope, strongly depend on the time the cluster is taken from the dwarf galaxy. After being captured by the MW on a new orbit, the cluster expands and eventually reaches the appropriate mass and size of Pal 14 after 11.5 Gyr while reproducing the observed MF. These simulations thus suggest that Pal 14 may have formed in a dwarf galaxy with a post-gas-expulsion initial half-mass radius and mass of $r_h=7$ pc and $8<M/10^4<10 $ M$_{\odot}$, respectively, with a high degree of primordial mass segregation.

The recently identified intercept $a_B$ tension of supernova (SN) magnitude-redshift relation between local ($z<0.0233$) and late-time ($z>0.0233$) Universe hints for either local-scale new physics or systematics. By comparing the intercepts of different SN groups in the PantheonPlus sample, we find the supernovae (SNe) in the third-rung distance ladder maintain a very stable $a_B$ over a wide redshift range ($0.003<z<2.3$), while the Cepheid-hosted SNe in the second-rung distance ladder presents a significant $a_B$ deviation, recovering the previously found $a_B$ tension but more specifically between the second and third rungs of the distance ladder. We then analyze the potential systematics that might trigger the $a_B$ tension, especially the redshift biases induced by the peculiar velocity. Without turning to the full machinery of matter density and velocity field reconstructions, we propose to directly simulate the corrections for the redshift biases to eliminate the $a_B$ tension, and then combine the corrected redshifts with the SH0ES Cepheid distance moduli to directly infer the Hubble constant without referring to the third-rung SNe. This first two-rung local distance ladder provides $H_0=73.4\pm1.0\;\mathrm{km/s/Mpc}$ consistent with SH0ES typical three-rung and first two-rung constraints. Further cross-checking with another independent SN compilation from the Carnegie Supernova Project, we find the first two-rung local distance ladders constructed directly from Cepheid, the tip of the red giant branch, and surface brightness fluctuations all consistently prefer $H_0>72\;\mathrm{km/s/Mpc}$. Therefore, the Hubble tension can be narrowed down to a tension between the Planck-CMB global constraint and the first two-rung local distance ladders, ruling out the third-rung SN systematics like a late-time transition in the SN absolute magnitude.

HERMES-Pathfinder is a space-borne mission based on a constellation of six nano-satellites flying in a low-Earth orbit. The 3U CubeSats, to be launched in early 2025, host miniaturized instruments with a hybrid Silicon Drift Detector/scintillator photodetector system, sensitive to both X-rays and gamma-rays. A seventh payload unit is installed onboard SpIRIT, an Australian-Italian nano-satellite developed by a consortium led by the University of Melbourne and launched in December 2023. The project aims at demonstrating the feasibility of Gamma-Ray Burst detection and localization using miniaturized instruments onboard nano-satellites. The HERMES flight model payloads were exposed to multiple well-known radioactive sources for spectroscopic calibration under controlled laboratory conditions. The analysis of the calibration data allows both to determine the detector parameters, necessary to map instrumental units to accurate energy measurements, and to assess the performance of the instruments. We report on these efforts and quantify features such as spectroscopic resolution and energy thresholds, at different temperatures and for all payloads of the constellation. Finally we review the performance of the HERMES payload as a photon counter, and discuss the strengths and the limitations of the architecture.

In many astronomical works, the structure of vector fields is analyzed, such as the differences in the celestial object coordinates in catalogs or the celestial object velocities, by decomposition into vector spherical harmonics (VSH). This method has shown high efficiency in many studies, but, at the same time, comparing the results obtained by different authors can cause difficulties associated with different approaches to building the VSH system and even with their different designations. To facilitate this task, this paper provides a comparison of the three VSH systems most often used in works on astrometry and stellar astronomy.

Stellar spot distribution has consequences on the observable periodic signals in long-time baseline ground-based photometry. We model the statistics of the dominating spots of two young and active Solar-type stars, V889 Her and LQ Hya, in order to obtain information on the underlying spot distribution, rotation of the star, as well as the orientation of the stellar axis of spin. By calculating estimates for spot-induced periodicities in independent subsets of photometric data, we obtain statistics based on the dominating spots in each subset, giving rise to largest-spot statistics accounting for stellar geometry and rotation, including differential rotation. Our simple statistical models are able to reproduce the observed distribution of photometric signals rather well. This also enables us to estimate the dependence of angular velocity of the spots as a function of latitude. Our results indicate that V889 Her has a non-monotonic differential rotation curve with a maximum angular velocity between latitudes of 37-40 deg and lower angular velocity at the pole than the equator. Our results for LQ Hya indicate that the star rotates much like a rigid body. Furthermore, the results imply that the monotonic Solar differential rotation curve may not be a universal model for other solar-type stars. The non-monotonicity of the differential rotation of V889 Her is commonly produced in magnetohydrodynamic simulations, which indicates that our results are realistic from a theoretical perspective.

Neutron stars change their structure with accumulation of dark matter. We study how their mass is influenced from the environment. Close to the sun, the dark matter accretion from the neutron star does not have any effect on it. Moving towards the galactic center, the density increase in dark matter results in increased accretion. At distances of some fraction of a parsec, the neutron star acquire enough dark matter to have its structure changed. We show that the neutron star mass decreases going towards the galactic centre, and that dark matter accumulation beyond a critical value collapses the neutron star into a black hole. Calculations cover cases varying the dark matter particle mass, self-interaction strength, and ratio between the pressure of dark matter and ordinary matter. This allow us to constrain the interaction cross section, $\sigma_{\rm dm}$, between nucleons and dark matter particles, as well as the dark matter self-interaction cross section.

Results of a study of physical parameters of stellar population in star formation regions in galaxies with signs of peculiarity NGC 3963 and NGC 7292 are presented. The study was carried out based on the analysis of photometric (UBVRI bands), H-alpha and spectroscopic data obtained by the authors, using evolutionary models of stellar population. Among 157 star formation regions identified in galaxies, the young stellar population mass estimates were obtained for 16 of them and the age estimates were obtained for 15. The age of star formation regions clearly correlates with the presence of emission in the H-alpha line: HII regions in the galaxies are younger than 6-8 Myr, and the regions without gas emission are older. The studied objects are included in the version 3 of our catalogue of photometric, physical and chemical parameters of star formation regions, which includes 1667 objects in 21 galaxies. Key aspects of the technique used to estimate the physical parameters and different relations between observational and physical parameters of the young stellar population in star formation regions are discussed.

Massive stars experience strong mass-loss, producing a dense, H-rich circumstellar medium (CSM). After the explosion, the collision and continued interaction of the supernova (SN) ejecta with the CSM power the light curve through the conversion of kinetic energy into radiation. When the interaction is strong, the light curve shows a broad peak and high luminosity lasting for a relatively long time. Also the spectral evolution is slower, compared to non-interacting SNe. Energetic shocks between the ejecta and the CSM create the ideal conditions for particle acceleration and production of high-energy (HE) neutrinos above 1 TeV. In this paper, we study four strongly-interacting Type IIn SNe: 2021acya, 2021adxl, 2022qml, and 2022wed to highlight their peculiar characteristics, derive the kinetic energy of the explosion and the characteristics of the CSM, infer clues on the possible progenitors and their environment and relate them to the production of HE neutrinos. The SNe analysed in this sample exploded in dwarf, star-forming galaxies and they are consistent with energetic explosions and strong interaction with the surrounding CSM. For SNe 2021acya and 2022wed, we find high CSM masses and mass-loss rates, linking them to very massive progenitors. For SN 2021adxl, the spectral analysis and less extreme CSM mass suggest a stripped-envelope massive star as possible progenitor. SN 2022qml is marginally consistent with being a Type Ia thermonuclear explosion embedded in a dense CSM. The mass-loss rates for all SNe are consistent with the expulsion of several solar masses of material during eruptive episodes in the last few decades before the explosion. Finally, we find that the SNe in our sample are marginally consistent with HE neutrino production.

Halo assembly bias is a phenomenon whereby the clustering of dark matter halos is dependent on halo properties, such as age, at fixed mass. Understanding the origin of assembly bias is important for interpreting the clustering of galaxies and constraining cosmological models. One proposed explanation for the origin of assembly bias is the truncation of mass accretion in low-mass halos in the presence of more massive halos, called 'arrested development.' Halos undergoing arrested development would have older measured ages and exhibit stronger clustering than equal mass halos that have not undergone arrested development. We propose a new method to test the validity of this explanation for assembly bias, and correct for it in cosmological N-body simulations. The method is based on the idea that the early mass accretion history of a halo, before arrested development takes effect, can be used to predict the late-time evolution of the halo in the absence of arrested development. We implement this idea by fitting a model to the early portion of halo accretion histories and extrapolating to late times. We then calculate 'corrected' masses and ages for halos based on this extrapolation and investigate how this impacts the assembly bias signal. We find that correcting for arrested development this way leads to a factor of two reduction in the strength of the assembly bias signal across a range of low halo masses. This result provides new evidence that arrested development is a cause of assembly bias and validates our approach to mitigating the effect.

The light curve of the TeV emission in GRB 221009A displays a smooth transition from an initial rapid rise to a slower rise and eventually a decay phase. The smooth temporal profile of the TeV emission suggests that it mainly results from an external shock. The temporal overlap between the prompt KeV-MeV emission and the early TeV afterglow indicates that external inverse Compton scattering (EIC) between the prompt KeV-MeV photons and the afterglow electrons is inevitable. Since the energy density of the prompt emission is much higher than that of the afterglow during the early phase, the EIC process dominates the cooling of afterglow electrons. The EIC scattering rate is influenced by the anisotropy of the seed photon field, which depends on the radii of the internal dissipation ($R_{\rm dis}$), where the prompt emission is produced, and that of the external shock ($R_{\rm ext}$), where the afterglow emission is produced. We investigate the EIC process for different values of $R_{\rm dis}/R_{\rm ext}$. We find that, for varying \( R_{\rm dis}/R_{\rm ext} \), the EIC scattering rate can differ by a factor of $\sim 2$. For GRB 221009A, the EIC emission is dominated during the early rising phase of the TeV afterglow. It then transitions to a phase dominated by the synchrotron self-Compton (SSC) emission as the intensity of the prompt emission decreases. Additionally, we investigate the effect of $\gamma \gamma$ absorption in the TeV afterglow caused by prompt MeV photons and find that it is insufficient to explain the early rapid rise in the TeV afterglow, even in the case of $R_{\rm dis}/R_{\rm ext} \sim 1$.

High redshift observations of 10$^9$ M$_\odot$ supermassive black holes (SMBHs) at $z \sim7$ and `Little Red Dots' that may host overmassive black holes at $z>4$ suggests the existence of so-called heavy seeds (>1000 M$_\odot$) in the early Universe. Recent work has suggested that the rapid assembly of halos may be the key to forming heavy seeds early enough in the Universe to match such observations without the need for extreme radiation fields or dark matter streaming velocities. We perform simulations of BH seed formation in 4 distinct idealised halo collapse scenarios; an isolated 10$^6$ M$_\odot$ minihalo, an isolated 10$^7$ M$_\odot$ atomic halo, the direct collision of two 10$^7$ M$_\odot$ halos and a fly-by collision of two 10$^7$ M$_\odot$ halos. We have shown that halo collisions create a central environment of enhanced density, inside which BH seeds can accrete at enhanced rates. For direct collisions, the gas density peaks are disrupted by the interaction, as the collisionless DM peaks pass through each other while the colliding gas is left in the center, removing the sink particle from its accretion source. When the central density peaks instead experience a fly-by interaction, the sink particle remains embedded in the dense gas and maintains enhanced accretion rates throughout the simulated period when compared to the isolated halo cases. Here the final mass of the sink particle achieved a factor of 2 greater in mass than in the isolated atomic halo case, and a factor of 3 greater than the minihalo case, reaching 10$^4$ M$_\odot$ via its 0.03 pc accretion radius. As the maximum halo mass before collapse is determined by the atomic cooling limit of a few times 10$^7$ M$_{\odot}$, the ability of halo-halo mergers to further boost accretion rates onto the central object may play a crucial role in growing SMBH seeds.

The long-term solar magnetic activity and its cyclical behaviour, which is maintained by a dynamo mechanism, are both still challenging for the astrophysics. In particular, an atypical event occurred between 1645 and 1715 when the solar activity was remarkably decreased and the number of sunspots got extremely reduced. However, it is still unclear what happened to the solar cycle. The discovery of longer activity minima in cool stars may shed light on the nature of the complex mechanisms involved in the long-term behaviour of the solar-stellar dynamo. Our aim is to explore if the G5V solar-like star HD 4915, which showed a striking chromospheric activity pattern in a previous study performed with HIRES data, could be considered a bona fide Maunder Minimum (hereafter MM) candidate. We have analyzed over 380 spectra acquired between 2003 and 2022 using HARPS and HIRES spectrographs. We carried out a detailed search of activity signatures in HD 4915 by using the Mount Wilson and the Balmer H$_{\alpha}$ activity indexes. This task was performed by means of the GLS periodogram. The new HARPS data show that the chromospheric activity of HD 4915 is not decreasing. In fact, the rise of the activity after the broad minimum in three years gets to the level of activity before that phase, suggesting that it is not entering into a MM phase. HD 4915 shows a distinctive activity behaviour initially attributed to a possible and incipient MM phase. The additional HARPS data allow us to discard a MM in the star. Our analysis shows that the complex activity pattern of HD 4915 could be ruled by a multiple activity cycle, being a shorter cycle of 4.8-yr modulated by a potential longer one. More activity surveys with extensive records and suitable cadence are crucial for accurate identification of stars in Magnetic Grand Minima.

We present a novel method to characterize dust depletion, namely, the depletion of metals into dust grains. We used observed correlations among relative abundances combining a total of 17 metals in diverse galactic environments, including the Milky Way (MW), Large Magellanic Cloud (LMC), Small Magellanic Cloud (SMC), and damped Lyman-$\alpha$ absorbers (DLAs) towards quasars and gamma-ray bursts (GRBs). We only considered the relative abundances of metals that qualify as tracers of dust and we used all available dust tracers. We find linear correlations among all studied dust tracers in a multidimensional space, where each dimension corresponds to an individual dust tracer. The fit to the linear correlations among the dust tracers describes the tendencies of different elements when depleting into dust grains. We determined the overall strength of dust depletion, $\Delta$, along individual lines of sight, based on the correlations among different dust tracers. We avoided any preference for specific dust tracers or any other assumptions by including all available dust tracers in this multidimensional space. We also determined the dust depletion of Kr, C, O, Cl, P, Zn, Ge, Mg, Cu, Si, Fe, Ni, and Ti. Finally, we offer simple guidelines for the application of the method to the study of the observed patterns of abundances and relative abundances. This has allowed for a straightforward determination of the overall strength of depletion and the dust depletion of individual elements. We also obtained an estimate for the gas-phase metallicity and identified any additional deviations due to the nucleosynthesis of specific stellar populations. Thus, we have established a unified methodology for characterizing dust depletion across cosmic time and diverse galactic environments, offering a valuable new approach to the study of dust depletion in studies of the chemical evolution of galaxies.

We present 850$\mu$m polarized observations of the molecular cloud G34.26+0.15 taken using the POL-2 polarimeter mounted on the James Clerk Maxwell Telescope (JCMT). G34.26+0.15 is a hub-filament system with ongoing high-mass star-formation, containing multiple HII regions. We extend the Histogram of Relative Orientations technique with an alternative application that considers the alignment of the magnetic field to the filaments and a HII region boundary, denoted as the filament alignment factor ($\xi_{F}$) and the ellipse alignment factor ($\xi_{E}$) respectively. Using these metrics, we find that, although in general the magnetic field aligns parallel to the filamentary structure within the system in the north-west, the magnetic field structure of G34.26+0.15 has been radically reshaped by the expansion of an evolved HII region in the south-east, which itself may have triggered further high-mass star formation in the cloud. Thus, we suggest high-mass star formation is both occurring through mass accretion as per the hub-filament model from one side, and through compression of gas under stellar feedback from the other. We also use HARP observations of C$^{18}$O from the CHIMPS survey to estimate the magnetic field strength across the cloud, finding strengths of $\sim$0.5-1.4 mG.

Analyses of major group mergers are key to understanding the evolution of large-scale structure in the Universe and the microphysical properties of the hot gas in these systems. We present imaging and spectral analyses of deep Chandra observations of hot gas structures formed in the major merger of the NGC 7618 and UGC 12491 galaxy groups and compare the observed hot gas morphology, temperatures, and abundances with recent simulations. The morphology of the observed multiple cold front edges and boxy wings are consistent with those expected to be formed by Kelvin-Helmholtz instabilities and gas sloshing in inviscid gas. The arc-shaped slingshot tail morphologies seen in each galaxy suggest that the dominant galaxies are near their orbital apogee after having experienced at least one core passage at a large impact parameter.

Radiation from the "plunging region" (the space between the innermost stable circular orbit (ISCO) and the black-hole (BH) surface) of an accretion flow onto a BH is supposed to add a small but significant contribution to the X-ray spectra of X-ray binary systems. The plunging region and its electromagnetic emission has been recently described by numerical and analytic calculations which lead to the conclusion that in the plunging region radiation is generated by the energy release through the action of a "leftover" stress in the vicinity of the ISCO and that the amount of this leftover can be chosen as a free parameter of the accretion-flow description. The present article aims to demonstrate that this is not true because the stress in the whole accretion flow onto a black hole is determined by its global transonic character enforced by the space-time structure of the accreting black hole. We use the slim-disc approximation (SDA) to illustrate this point. In our article we compare models obtained with the SDA with results of numerical simulations and of analytical models based on the assumption that accreting matter flows along geodesics. We show that the latter cannot describe adequately the physics of astrophysical accretion onto a BH because 1. particles on geodesics cannot emit electromagnetic radiation, 2. they ignore the global transonic character of the accretion flow imposed by the presence of a stationary horizon in the BH spacetime; a presence that fixes a unique value of the angular momentum at the BH surface for a solution to exist. Therefore the fact that geodesics-based models reproduce the trans-ISCO behaviour of GRRMHD simulations proves the physical reality of neither. We show also that the claimed detection of plunging-region emission in the spectrum of an X-ray binary is unsubstantiated.

This study investigates the timing and spectral characteristics of X-ray bursts from the neutron star system EXO 0748-676 using the NuSTAR observatory's FPMA and FPMB instruments in the 3-79 keV range. We identify Type I X-ray bursts driven by thermonuclear explosions on the neutron star's surface, notably a significant burst at \(X = 18,479.97\), indicating rapid energy release, followed by a recoil burst at \(X = 19,463.97\), reflecting stabilization. The correlation between burst timing and the neutron star's optical period suggests modulation by its rotation and periodic accretion dynamics. Spectral modeling reveals a photon index of \( \Gamma = 1.24 \pm 0.014 \) and a cutoff energy of \( E_C = 36.20 \pm 1.04 \; \text{keV} \), indicating a hot corona around the neutron star. The measured flux of approximately \( (381.17 \pm 0.014) \times 10^{-12} \; \text{erg cm}^{-2} \text{s}^{-1} \) underscores the dynamic nature of accretion-driven systems. Calculated luminosities derived from distance estimates range from \( (3.86 \pm 0.239) \times 10^{36} \; \text{erg/s} \) to \( (2.3 \pm 0.177) \times 10^{36} \; \text{erg/s} \). Comparative analysis with prior observations from the IBIS/ISGRI instrument on the INTEGRAL satellite shows variability in emission characteristics, including softer photon indices and higher cutoff energies in 2003 and 2004. Our examination of smaller energy gaps (3-7 keV, 7-12 keV, etc.) reveals energy-dependent behavior in burst characteristics, enhancing our understanding of nuclear burning phases. Overall, these findings validate models describing Type I X-ray bursts and lay the groundwork for future investigations into similar astrophysical systems and stellar evolution processes in extreme environments.

Field level statistics, such as the minimum spanning tree (MST), have been shown to be a promising tool for parameter inference in cosmology. However, applications to real galaxy surveys are challenging, due to the presence of small scale systematic effects and non-trivial survey selection functions. Since many field level statistics are 'hard-wired', the common practice is to forward model survey systematic effects to synthetic galaxy catalogues. However, this can be computationally demanding and produces results that are a product of cosmology and systematic effects, making it difficult to directly compare results from different experiments. We introduce a method for inverting survey systematic effects through a Monte Carlo subsampling technique where galaxies are assigned probabilities based on their galaxy weight and survey selection functions. Small scale systematic effects are mitigated through the addition of a point-process smoothing technique called jittering. The inversion technique removes the requirement for a computational and labour intensive forward modelling pipeline for parameter inference. We demonstrate that jittering can mask small scale theoretical uncertainties and survey systematic effects like fibre collisions and we show that Monte Carlo subsampling can remove the effects of survey selection functions. We outline how to measure field level statistics from future surveys.

Millimeter emitting dust grains have sizes that make them susceptible to drift in protoplanetary disks due to a difference between their orbital speed and that of the gas. The characteristic drift timescale depends on the surface density of the gas. By comparing disk radii measurements from ALMA CO and continuum observations at millimeter wavelengths, the gas surface density profile and dust drift time can be self-consistently determined. We find that profiles which match the measured dust mass have very short drift timescales, an order of magnitude or more shorter than the stellar age, whereas profiles for disks that are on the cusp of gravitational instability, defined via the minimum value of the Toomre parameter, Qmin ~ 1-2, have drift timescales comparable to the stellar lifetime. This holds for disks with masses of dust > 5 MEarth across a range of absolute ages from less than 1 Myr to over 10 Myr. The inferred disk masses scale with stellar mass as Mdisk ~ Mstar / 5Qmin. This interpretation of the gas and dust disk sizes simultaneously solves two long standing issues regarding the dust lifetime and exoplanet mass budget and suggests that we consider millimeter wavelength observations as a window into an underlying population of particles with a wide size distribution in secular evolution with a massive planetesimal disk.

For radio transients, an inverted spectrum (defined as $\alpha > 0$ for a power law spectrum $S_{\nu}\propto \nu^{\alpha}$) constrains physical properties, which in principle can be a useful criterion for selecting specific targets of interest in a transient search. To test and develop this concept, we have searched epoch 1 of the Very Large Array Sky Survey (VLASS; 3.0 GHz) and the VLITE Commensal Sky Survey (VCSS; 340 MHz) for radio transients with inverted spectra. We discover a sample of 22 inverted-spectra transient candidates that are not associated with cataloged active galactic nuclei (AGNs). To the best of our knowledge, none of our candidates have transient counterparts at other wavelengths, and only one has previously been reported as a radio transient. We find that our candidates evolve slowly over years and show either highly inverted spectra or peaked spectra over $\sim$1--3 GHz. Within our sample, nine candidates are matched to optical centers of galaxies and have estimated radio spectral luminosities of $L_{3.0\mathrm{GHz}}\sim10^{30}-10^{33}\,\mathrm{erg}\,\mathrm{s}^{-1}\,\mathrm{Hz}^{-1}$. Based on the observed properties, we find the most plausible transient classification for our candidates to be relativistic tidal disruption events. However, we are unable to fully rule out variable or transient AGNs with highly inverted spectra. Upon examining physical constraints, we confirm that mainly relativistic transients (on-axis or off-axis) with equipartition energy $E_{\mathrm{eq}}\gtrsim10^{49}-10^{53}\,\mathrm{erg}$ are expected from searching VLASS and VCSS based on inverted spectra. The obtainable physical constraints, however, can be weak due to degeneracy introduced by viewing angle.

Recent analyses of FGK stars in open clusters have helped clarify the precision with which a star's rotation rate and lithium content can be used as empirical indicators for its age. Here we apply this knowledge to stars observed by Kepler. Rotation periods are drawn from previous work; lithium is measured from new and archival Keck/HIRES spectra. We report rotation-based ages for 23,813 stars (harboring 795 known planets) for which our method is applicable. We find that our rotational ages recover the ages of stars in open clusters spanning 0.04-2.5 Gyr; they also agree with over 90% of the independent lithium ages. The resulting yield includes 63 planets younger than 1 Gyr at 2$\sigma$, and 109 with median ages below 1 Gyr. This is about half the number expected under the classic assumption of a uniform star formation history. The age distribution that we observe, rather than being uniform, shows that the youngest stars in the Kepler field are 3-5 times rarer than stars 3 Gyr old. This trend holds for both known planet hosts and for the parent stellar sample. We attribute this "demographic cliff" to a combination of kinematic heating and a declining star formation rate in the Galaxy's thin disk, and highlight its impact on the age distribution of known transiting exoplanets.

Extremely-low-mass white dwarfs (ELM WDs) with non-degenerate companions are believed to originate from solar-type main-sequence binaries undergoing stable Roche lobe overflow mass transfer when the ELM WD progenitor is at (or just past) the termination of the main-sequence. This implies that the orbital period of the binary at the onset of the first mass transfer phase must have been $\lesssim 3-5$ d. This prediction in turn suggests that most of these binaries should have tertiary companions since $\approx 90$ per cent of solar-type main-sequence binaries in that period range are inner binaries of hierarchical triples. Until recently, only precursors of this type of binaries have been observed in the form of EL CVn binaries, which are also known for having tertiary companions. Here, we present high-angular-resolution images of TYC 6992-827-1, an ELM WD with a sub-giant (SG) companion, confirming the presence of a tertiary companion. Furthermore, we show that TYC 6992-827-1, along with its sibling TYC 8394-1331-1 (whose triple companion was detected via radial velocity variations), are in fact descendants of EL CVn binaries. Both TYC 6992-827-1 and TYC 8394-1331-1 will evolve through a common envelope phase, which depending on the ejection efficiency of the envelope, might lead to a single WD or a tight double WD binary, which would likely merge into a WD within a few Gyr due to gravitational wave emission. The former triple configuration will be reduced to a wide binary composed of a WD (the merger product) and the current tertiary companion.

Comets, asteroids and moons that orbit stars and planets exterior to our solar system are prefixed with "exo". While the existence of these objects is certain, our understanding of their physical properties, composition, and diversity is still in its infancy, especially when compared to similar objects within our own solar system. This chapter introduces the topics of exocomets, exoasteroids, and exomoons, putting in context three emerging subfields in astronomy that, despite being relatively small, have experienced rapid growth over the past decade.

We present new ALMA continuum and spectral observations of the MUSE Ultra Deep Field (MUDF), a $2\times 2$ arcmin$^2$ region with ultradeep multiwavelength imaging and spectroscopy hosting two bright $z\approx 3.22$ quasars used to study intervening gas structures in absorption. Through a blind search for dusty galaxies, we identified a total of seven high-confidence sources, six of which with secure spectroscopic redshifts. We estimate galaxy dust and stellar masses ($M_{\rm dust}\simeq 10^{7.8-8.6}\,M_{\odot}$, $M_{\star}\simeq 10^{10.2-10.7}\,M_{\odot}$), as well as star formation rates (${\rm SFR}\simeq 10^{1.2-2.0}\,M_{\odot}\,{\rm yr^{-1}} $) which show that most of these galaxies are massive and dust-obscured similar to coeval (sub-)millimeter galaxies. All six spectroscopically-confirmed galaxies are within $500~\rm km~s^{-1}$ of metal absorption lines observed in the quasar sightlines, corresponding to $100\%$ association rate. We also find that four of these galaxies belong to groups in which they are among the most massive members. Within the multiple group galaxies associated to the same absorption system, the ALMA sources are not always the closest in projection, but they are often aligned with the gaseous structures in velocity space. This suggests that these massive galaxies occupy the center of the potential well of the gas structures traced in absorption. However, albeit the low number density of sources identified with ALMA, our study may indicate that absorbers seem to infrequently originate in the inner circumgalactic medium of these galaxies. Instead, they appear to be better tracers of the gas distributed in the large-scale structure that host them.

Observations of the Galactic bulge revealed an excess of short-timescale gravitational microlensing events that are generally attributed to a large population of free-floating or wide-orbit exoplanets. However, in recent years, some authors suggested that planetary-mass primordial black holes (PBHs) comprising a substantial fraction (1-10%) of the dark matter in the Milky Way may be responsible for these events. If that was the case, a large number of short-timescale microlensing events should also be seen toward the Magellanic Clouds. Here we report the results of a high-cadence survey of the Magellanic Clouds carried out from October 2022 through May 2024 as part of the Optical Gravitational Lensing Experiment (OGLE). We observed almost 35 million source stars located in the central regions of the Large and Small Magellanic Clouds and found only one long-timescale microlensing event candidate. No short-timescale events were detected despite high sensitivity to such events. That allows us to infer the strongest available limits on the frequency of planetary-mass PBHs in dark matter. We find that PBHs and other compact objects with masses from $1.4 \times 10^{-8}\,M_{\odot}$ (half of the Moon mass) to $0.013\,M_{\odot}$ (planet/brown dwarf boundary) may comprise at most 1% of dark matter. That rules out the PBH origin hypothesis for the short-timescale events detected toward the Galactic bulge and indicates they are caused by the population of free-floating or wide-orbit planets.

A significant interest has emerged recently in assessing whether collimated and ultra-relativistic outflows can be produced by a long-lived remnant from a binary neutron-star (BNS) merger, with different approaches leading to different outcomes. To clarify some of the aspect of this process, we report the results of long-term (\ie $\sim~110\,{\rm ms}$) state-of-the-art general-relativistic magnetohydrodynamics simulations of the inspiral and merger of a BNS system of magnetized stars. We find that after $\sim~50\,{\rm ms}$ from the merger, an $\alpha$-$\Omega$~dynamo driven by the magnetorotational instability (MRI) sets-in in the densest regions of the disk and leads to the breakout of the magnetic-field lines from the accretion disk around the remnant. The breakout, which can be associated with the violation of the Parker-stability criterion, is responsible for the generation of a collimated, magnetically-driven outflow with only mildly relativistic velocities that is responsible for a violent eruption of electromagnetic energy. We provide evidence that this outflow is partly collimated via a Blandford-Payne mechanism driven by the open field lines anchored in the inner disk regions. Finally, by including or not the radiative transport via neutrinos, we determine the role they play in the launching of the collimated wind. In this way, we conclude that the mechanism of magnetic-field breakout we observe is robust and takes place even without neutrinos. Contrary to previous expectations, the inclusion of neutrinos absorption and emission leads to a smaller baryon pollution in polar regions, and hence accelerates the occurrence of the breakout, yielding a larger electromagnetic luminosity. Given the mildly relativistic nature of these disk-driven breakout outflows, it is difficult to consider them responsible for the jet phenomenology observed in short gamma-ray bursts.

Massive stars are predominantly born in stellar associations or clusters. Their radiation fields, stellar winds, and supernovae strongly impact their local environment. In the first few million years of a cluster's life, massive stars are dynamically ejected running away from the cluster at high speed. However, the production rate of dynamically ejected runaways is poorly constrained. Here we report on a sample of 55 massive runaway stars ejected from the young cluster R136 in the Large Magellanic Cloud. Astrometric analysis with Gaia reveals two channels of dynamically ejected runaways. The first channel ejects massive stars in all directions and is consistent with dynamical interactions during and after the birth of R136. The second channel launches stars in a preferred direction and may be related to a cluster interaction. We find that 23-33% of the most luminous stars initially born in R136 are runaways. Model predictions have significantly underestimated the dynamical escape fraction of massive stars. Consequently, their role in shaping and heating the interstellar and galactic medium, along with their role in driving galactic outflows, is far more important than previously thought.

A gaseous counter-rotating galaxy is a galaxy containing a gas component with opposite angular momentum to the main stellar disk. The counter-rotating gas provides direct evidence for the accretion of external material, a key aspect in hierarchical galaxy evolution. We identified 303 gaseous counterrotators out of 9992 galaxies in MaNGA. The majority of the counterrotators are early-types. This implies their formation is highly correlated with early-type galaxies although it is still difficult to know if one leads to the other. To disentangle which of the galaxy characteristics within a morphological class were changed by the accretion of counter-rotating gas, we carefully selected a comparison sample with similar fundamental galactic properties, but co-rotation in gas. This comparison shows that gaseous counter-rotation correlates with weak rotation in the stellar component, high central concentration of star forming regions, if present, and a higher fraction of central low ionization emission regions (cLIER) galaxies. The light distributions of the stellar components, dust and HI content (both low), and overall suppressed star formation rates are similar for both samples and seem typical for the morphological class. We claim that elliptical and about half of the lenticular counterrotators, those with weak rotation in the stellar component in the outskirts and central regions, likely have a major merger origin for the gas acquisition, and the other half of lenticulars, with stronger stellar rotation, may have a minor merger or pure gas accretion origin.

The Ingot WFS belongs to a class of pupil-plane WFSs designed to address the challenges posed by Sodium Laser Guide Stars, and consists of a combination of refractive and reflective surfaces, arranged into a complex prismatic shape that extends in three dimensions. Specifically, it leverages the Scheimpflug principle to sense the full 3D volume of such elongated, time-varying sources, thus optimizing the performance of the next-generation AO-assisted giant telescopes. In this work we discuss the geometrical and optical motivations endorsing the development of this class of WFSs, showing the different configurations we propose to the AO community. We also provide a first order comparative analysis with other approaches and review the state-of-the-art of the Ingot project, including improvements made in the laboratory and future milestones.

The Ingot WFS was designed to overcome some of the challenges present in classical wavefront sensors when they deal with sodium LGSs. This innovative sensor works by sensing the full 3D volume of the elongated LGS and is suitable for use in very large telescopes. A test bench has been assembled at the INAF - Osservatorio Astronomico di Padova laboratories to test and characterize the functioning of the Ingot WFS. In this work, we summarize the main results of the tests performed on a new search algorithm. Then, we move towards a more accurate simulation of the sodium LGS by replicating real time-varying sodium layer profiles. The study of their impact on the ingot pupil signals is described in this work.

Future space observatories dedicated to direct imaging and spectroscopy of extra-solar planets will require ultra-low-noise detectors that are sensitive over a broad range of wavelengths. Silicon charge-coupled devices (CCDs), such as EMCCDs, Skipper CCDs, and Multi-Amplifier Sensing CCDs, have demonstrated the ability to detect and measure single photons from ultra-violet to near-infrared wavelengths, making them candidate technologies for this application. In this context, we study a relatively unexplored source of low-energy background coming from Cherenkov radiation produced by energetic charged particles traversing a silicon detector. In the intense radiation environment of space, energetic cosmic rays produce high-energy tracks and more extended halos of low-energy Cherenkov photons, which are detectable with ultra-low-noise detectors. We present a model of this effect that is calibrated to laboratory data, and we use this model to characterize the residual background rate for ultra-low noise silicon detectors in space. We find that the rate of cosmic-ray-induced Cherenkov photon production is comparable to other detector and astrophysical backgrounds that have previously been considered.

Metals in the diffuse, ionized gas at the boundary between the Milky Way's interstellar medium (ISM) and circumgalactic medium (CGM), known as the disk-halo interface (DHI), are valuable tracers of the feedback processes that drive the Galactic fountain. However, metallicity measurements in this region are challenging due to obscuration by the Milky Way ISM and uncertain ionization corrections that affect the total hydrogen column density. In this work, we constrain the ionization corrections to neutral hydrogen column densities using precisely measured electron column densities from the dispersion measure of pulsars that lie in the same globular clusters as UV-bright targets with high-resolution absorption spectroscopy. We address the blending of absorption lines with the ISM by jointly fitting Voigt profiles to all absorption components. We present our metallicity estimates for the DHI of the Milky Way based on detailed photoionization modeling to the absorption from ionized metal lines and ionization-corrected total hydrogen columns. Generally, the gas clouds show a large scatter in metallicity, ranging between $0.04-3.2\ Z_{\odot}$, implying that the DHI consists of a mixture of gaseous structures having multiple origins. We estimate the inflow and outflow timescales of the DHI ionized clouds to be $6 - 35$ Myr. We report the detection of an infalling cloud with super-solar metallicity that suggests a Galactic fountain mechanism, whereas at least one low-metallicity outflowing cloud ($Z < 0.1\ Z_{\odot}$) poses a challenge for Galactic fountain and feedback models.

Dark matter haloes form from the collapse of matter around special positions in the initial field, those where the local matter flows converge to a point. For such a triaxial collapse to take place, the energy shear tensor -- the source of the evolution of the inertia tensor -- must be positive definite. It has been shown that this is indeed the case for the energy shear tensor of the vast majority of protohaloes. At generic positions in a Gaussian random field, the trace and traceless parts of the tensor are independent of one another. Here we show that, on the contrary, in positive definite matrices they correlate strongly, and these correlations are very similar to those exhibited by protohaloes. Moreover, while positive-definiteness ensures that an object will collapse, it does not specify when. Previous work has shown that the trace of the energy tensor -- the energy overdensity -- exhibits significant scatter in its values, but must lie above a critical `threshold' value for the halo to collapse by today. We show that suitable combinations of the eigenvalues of the traceless part are able to explain a substantial part of the scatter of the trace. These variables provide an efficient way to parameterise the initial value of the energy overdensity, allowing us to formulate an educated guess for the threshold of collapse. We validate our ansatz by measuring the distribution of several secondary properties of protohaloes, finding good agreement with our analytical predictions.

The influence of Active Galactic Nuclei (AGN) on star formation within their host galaxies remains a topic of intense debate. One of the primary challenges in quantifying the star formation rate (SFR) within AGN hosts arises from the prevalent assumption in most methodologies, which attribute gas excitation to young stars alone. However, this assumption does not consider the contribution of the AGN to the ionization of the gas in their environment. To address this issue, we evaluate the use of strong optical emission lines to obtain the SFR surface density ($\Sigma{\rm SFR_{AGN}}$) in regions predominantly ionized by an AGN, using a sample of 293 AGN hosts from the MaNGA survey, with SFR measurements available through stellar population fitting. We propose calibrations involving the H$\alpha$ and [O\,{\sc iii}]$\lambda$5007 emission lines, which can be used to determine $\Sigma{\rm SFR_{AGN}}$, resulting in values consistent with those estimated through stellar population fitting.

Effective image post-processing algorithms are vital for the successful direct imaging of exoplanets. Standard PSF subtraction methods use techniques based on a low-rank approximation to separate the rotating planet signal from the quasi-static speckles, and rely on signal-to-noise ratio maps to detect the planet. These steps do not interact or feed each other, leading to potential limitations in the accuracy and efficiency of exoplanet detection. We aim to develop a novel approach that iteratively finds the flux of the planet and the low-rank approximation of quasi-static signals, in an attempt to improve upon current PSF subtraction techniques. In this study, we extend the standard L2 norm minimization paradigm to an L1 norm minimization framework to better account for noise statistics in the high contrast images. Then, we propose a new method, referred to as Alternating Minimization Algorithm with Trajectory, that makes a more advanced use of estimating the low-rank approximation of the speckle field and the planet flux by alternating between them and utilizing both L1 and L2 norms. For the L1 norm minimization, we propose using L1 norm low-rank approximation, a low-rank approximation computed using an exact block-cyclic coordinate descent method, while we use randomized singular value decomposition for the L2 norm minimization. Additionally, we enhance the visibility of the planet signal using a likelihood ratio as a postprocessing step. Numerical experiments performed on a VLT/SPHERE-IRDIS dataset show the potential of AMAT to improve upon the existing approaches in terms of higher S/N, sensitivity limits, and ROC curves. Moreover, for a systematic comparison, we used datasets from the exoplanet data challenge to compare our algorithm to other algorithms in the challenge, and AMAT with likelihood ratio map performs better than most algorithms tested on the exoplanet data challenge.

As the descendants of stars with masses less than 8 M$_{\odot}$ on the main sequence, white dwarfs provide a unique way to constrain planetary occurrence around intermediate-mass stars (spectral types BAF) that are otherwise difficult to measure with radial-velocity or transit surveys. We update the analysis of more than 250 ultraviolet spectra of hot ($13{,}000$ K $< T_{\mathrm{eff}} <$ $30{,}000$ K), young (less than $800$ Myr) white dwarfs collected by the Hubble Space Telescope, which reveals that more than 40% of all white dwarfs show photospheric silicon and sometimes carbon, signpost for the presence of remnant planetary systems. However, the fraction of white dwarfs with metals significantly decreases for massive white dwarfs (M$_{\rm WD}~>$ 0.8 M$_{\odot}$), descendants of stars with masses greater than 3.5 M$_{\odot}$ on the main sequence, as just $11^{+6}_{-4}$% exhibit metal pollution. In contrast, $44\pm6$% of a subset of white dwarfs (M$\rm _{WD}~<$ 0.7 M$_{\odot}$) unbiased by the effects of radiative levitation are actively accreting planetary debris. While the population of massive white dwarfs is expected to be influenced by the outcome of binary evolution, we do not find merger remnants to broadly affect our sample. We connect our measured occurrence rates of metal pollution on massive white dwarfs to empirical constraints into planetary formation and survival around stars with masses greater than 3.5 M$_{\odot}$ on the main sequence.

Galaxy mergers can enhance star formation rates throughout the merger sequence, with this effect peaking around the time of coalescence. However, owing to a lack of information about their time of coalescence, post-mergers could only previously be studied as a single, time-averaged population. We use timescale predictions of post-coalescence galaxies in the UNIONS survey, based on the Multi-Model Merger Identifier deep learning framework (\textsc{Mummi}) that predicts the time elapsed since the last merging event. For the first time, we capture a complete timeline of star formation enhancements due to galaxy mergers by combining these post-merger predictions with data from pre-coalescence galaxy pairs in SDSS. Using a sample of $564$ galaxies with $M_* \geq 10^{10} M_\odot$ at $0.005 < z < 0.3$ we demonstrate that: 1) galaxy mergers enhance star formation by, on average, up to a factor of two; 2) this enhancement peaks within 500 Myr of coalescence; 3) enhancements continue for up to 1~Gyr after coalescence; and 4) merger-induced star formation significantly contributes to galaxy mass assembly, with galaxies increasing their final stellar masses by, $10\%$ to $20\%$ per merging event, producing on average $\log(M_*/M_\odot) = {9.56_{-0.19}^{+0.13}}$ more mass than non-interacting star-forming galaxies solely due to the excess star formation.

(Abridged) Mechanisms for quenching star formation in galaxies remain hotly debated, with galaxy mergers an oft-proposed pathway. In Ellison et al. (2022) we tested this scenario by quantifying the fraction of recently and rapidly quenched post-starbursts (PSBs) in a sample of post-merger galaxies identified in the Ultraviolet Near Infrared Optical Northern Survey (UNIONS). With our recent development of the Multi-Model Merger Identifier (MUMMI) neural network ensemble (Ferreira et al. 2024a,b), we are now additionally able to predict the time since coalescence (T_PM) for the UNIONS post-merger galaxies up to T_PM = 1.8 Gyr, allowing us to further dissect the merger sequence and measure more precisely when quenching occurs. Based on a sample of 5927 z<0.3 post-mergers identified in UNIONS, we find that the post-coalescence population evolves from one dominated by star-forming (and starbursting) galaxies at 0 < T_PM < 0.16 Gyr, through to a population that is dominated by quenched galaxies by T_PM ~ 1.5 Gyr. We find a PSB excess throughout the post-merger regime, but with a clear peak at 0.16 < T_PM < 0.48 Gyr. In this post-merger time range PSBs are more common than in control galaxies by factors of 30-100, an excess that drops sharply at longer times since merger. We also quantify the fraction of PSBs that are mergers and find that the majority (75%) of classically selected E+A are identified as mergers, with a lower merger fraction (60%) amongst PCA selected this http URL results demonstrate that 1) galaxy-galaxy interactions can lead to rapid post-merger quenching within 0.5 Gyr of coalescence, 2) the majority of (but not all) PSBs at low z are linked to mergers and 3) quenching pathways are diverse, with different PSB selection techniques likely identifying galaxies quenched by different physical processes with an additional dependence on stellar mass.

Context. Characterizing mission-accessible asteroids using telescopic observations is fundamental for target-selection and planning for spacecraft missions. Near-Earth asteroids on Earth-like orbits are of particular importance for applications such as asteroid mining. Aims. 2001 QJ142 is a tiny (D $\leq$ 100 m) near-Earth asteroid on an Earth-like orbit with a semimajor axis of 1.06 au, orbital eccentricity of 0.09, and orbital inclination of 3.10$^{\circ}$. We aim to characterize 2001 QJ142 using ground-based observations with future spacecraft missions in mind. Methods. We performed visible multicolor photometry of 2001 QJ142 using the TriCCS on the Seimei 3.8 m telescope in February 2024. We also revisited the images taken with the Suprime-Cam on the Subaru 8.2 m telescope in August 2012. Results. Visible color indices of 2001 QJ142 indicate that 2001 QJ142 is a C- or X-complex asteroid. We detect a possible fast rotation with a period of about 10 min, which is consistent with a previous report. The geometric albedo of 2001 QJ142 is derived to be about 0.3 from a slope of its photometric phase curve, which is consistent with an albedo derived from thermal observations with updated physical quantities. A straightforward interpretation is that 2001 QJ142 is either an E- or M-type asteroid, although surface properties of such tiny fast-rotating asteroids are not well understood. Conclusions. We infer that 2001 QJ142 is a fast-rotating mission-accessible E- or M-type near-Earth asteroid. More characterizations of tiny asteroids are particularly important for a deeper understanding of their nature.

In this work, we explore the possibility of the Hall effect and ambipolar diffusion as a mechanism for fast reconnection. The reconnected flux of our resistive and resistive+Hall simulations replicates the GEM results. Furthermore, we investigate, for the first time, the effect of ambipolar diffusion in the GEM. The reconnected flux of the resistive+ambipolar and resistive+Hall+ambipolar simulations showed increases of up to 75\% and 143\%, respectively, compared to the resistive and resistive+Hall simulations, showing that ambipolar diffusion contributes significantly to the reconnected flux. Our second scenario has a magnetic Harris field without perturbations but with an out-of-plane component, known as a guide field. We found that the reconnection rate increased faster with ambipolar diffusion, reaching values close to 0.1 for the resistive+Hall+ambipolar simulation followed by the resistive+Hall. These two simulations achieved the highest kinetic energy, implying more efficient energy conversion during reconnection.

The next generation of experiments for rare-event searches based on skipper Charge Coupled Devices (skipper-CCDs) presents new challenges for the sensor packaging and readout. Scaling the active mass and simultaneously reducing the experimental backgrounds in orders of magnitude requires a novel high-density silicon-based package that must be massively produced and tested. In this work, we present the design, fabrication, testing, and empirical signal model of a multi-channel silicon package. In addition, we outline the chosen specifications for the ongoing production of 1500 wafers that will add up to a 10 kg skipper-CCD array with 24000 readout channels.

Core-Collapse Supernovae (CCSNe) remain a critical focus in the search for gravitational waves (GWs) in modern astronomy. Their detection and subsequent analysis will enhance our understanding of the explosion mechanisms in massive stars. This paper investigates a combination of time-frequency analysis tools with convolutional neural network (CNN) to enhance the detection of GWs originating from CCSNe. The CNN was trained in the time-frequency domain using simulated data from Advanced LIGO (aLIGO). We preprocess the data using the widely used Short-Time Fourier Transform (STFT) and the Q-transform. Our CNN model achieves a remarkable 100% prediction rate for CCSNe GW events with a Signal-to-Noise Ratio (SNR) greater than 0.5. We found that the STFT outperforms the Q-transform for SNRs below 0.5.

We have performed a critical evaluation of the membership status of all variable stars in globular clusters recorded in the Catalogue of Variable Stars in Globular Clusters (CVSGC) curated by Christine Clement. To this end, we employed the systematic and bulky membership analysis performed by E. Vasiliev and H. Baumgardt based on the proper motions and parallaxes given in Gaia-EDR3. We found numerous variables in the CVSGC which are in fact field stars, which is particularly the case for globular clusters located in the Galactic bulge. Using the newly acquired list of reliable cluster members we examine the Oosterhoff dichotomy present among the Milky Way (MW) globular clusters using their RR Lyrae stars content. We confirm the presence of the Oosterhoff gap, separating both Oosterhoff groups. The Oosterhoff gap is mostly populated by globular clusters associated with MW dwarf galaxies and globular clusters with a low number of fundamental mode RR Lyrae variables. Several of the clusters in the Oosterhoff gap were previously linked to past merger events (e.g. Kraken/Heracles).

Recent work suggests that many luminous blue variables (LBVs) and B[e] supergiants (sgB[e]) are isolated, implying that they may be products of massive binaries, kicked by partner supernovae (SNe). However, the evidence is somewhat complex and controversial. To test this scenario, we measure the proper-motion velocities for these objects in the LMC and SMC, using Gaia Data Release 3. Our LMC results show that the kinematics, luminosities, and IR properties point to LBVs and sgB[e] stars being distinct classes. We find that Class 1 LBVs, which have dusty nebulae, and sgB[e] stars both show velocity distributions comparable to that of SMC field OBe stars, which are known to have experienced SN kicks. The sgB[e] stars are faster, plausibly due to their lower average masses. However, Class 2 LBVs, which are luminous objects without dusty nebulae, show no signs of acceleration, therefore suggesting that they are single stars, pre-SN binaries, or perhaps binary mergers. The candidate LBV Class 3 stars, which are dominated by hot dust, are all confirmed sgB[e] stars; their luminosities and velocities show that they simply represent the most luminous and massive of the sgB[e] class. There are very few SMC objects, but the sgB[e] stars are faster than their LMC counterparts, which may be consistent with expectations that lower-metallicity binaries are tighter, causing faster ejections. We also examine the distinct class of dust-free, weak-lined sgB[e] stars, finding that the SMC objects have the fastest velocities of the entire sample.

Discrepancy between the measurements of Hubble constant $H_{0}$ from the cosmic microwave background (CMB) and the local distance ladder is the most serious challenge to the standard $\Lambda$CDM model. Recent researches point out that it might be related with the violation of cosmological principle. Here, we investigate the impact of dipole-monopole correction on the constraints of $H_{0}$ utilizing the dipole fitting method based on the $\Lambda$CDM model and cosmography method. Our results show that the dipole-monopole correction can reduce the constraints of $H_{0}$ from a larger value consistent with SH0ES results to a smaller value consistent with Planck results. This finding can effectively alleviate the Hubble tension. Through making redshift tomography and model-independent analyses, we confirm that our findings are independent of redshift and cosmological model. In addition, the theoretical prediction of $H(z)/(1+z)$ reconstructed by the constraints of $\Lambda$CDM model with the dipole correction is in agreement with BAOs measurements including 5 DESI BAOs within 1$\sigma$ range except datapoint at z = 0.51. Our research suggests that the Hubble tension originates from new physics beyond the standard $\Lambda$CDM model, which might lead to a violation of the cosmological principle.

The solar interior is filled with turbulent thermal convection, which plays a key role in the energy and momentum transport and the generation of the magnetic field. The turbulent flows in the solar interior cannot be optically detected due to its significant optical depth. Currently, helioseismology is the only way to detect the internal dynamics of the Sun. However, long-duration data with a high cadence is required and only the temporal average can be inferred. To address these issues effectively, in this study, we develop a novel method to infer the solar internal flows using a combination of radiation magnetohydrodynamic numerical simulations and machine/deep learning. With the application of our new method, we can evaluate the large-scale flow at 10 Mm depth from the solar surface with three snapshots separated by an hour. We also apply it to the observational data. Our method is highly consistent with the helioseismology, whereas the amount of input data is significantly reduced.

We present a neural network emulator to constrain the thermal parameters of the intergalactic medium (IGM) at $\displaystyle{5.4}\le{z}\le{6.0}$ using the Lyman-$\displaystyle\alpha$ (Ly$\displaystyle\alpha$) forest flux auto-correlation function. Our auto-differentiable JAX-based framework accelerates the surrogate model generation process using approximately 100 sparsely sampled Nyx hydrodynamical simulations with varying combinations of thermal parameters, i.e., the temperature at mean density $\displaystyle{T}_{0}$, the slope of the temperature$\displaystyle-$density relation $\displaystyle\gamma$, and the mean transmission flux $\displaystyle{\langle}{F}{\rangle}$. We show that this emulator has a typical accuracy of 1.0% across the specified redshift range. Bayesian inference of the IGM thermal parameters, incorporating emulator uncertainty propagation, is further expedited using NumPyro Hamiltonian Monte Carlo. We compare both the inference results and computational cost of our framework with the traditional nearest-neighbor interpolation approach applied to the same set of mock Ly$\alpha$ flux. By examining the credibility contours of the marginalized posteriors for $\displaystyle{T}_{0},\gamma,\text{and}{\langle}{F}{\rangle}$ obtained using the emulator, the statistical reliability of measurements is established through inference on 100 realistic mock data sets of the auto-correlation function.

How black holes are formed remains an open and fundamental question in Astrophysics. Despite theoretical predictions, it lacks observations to understand whether the black hole formation experiences a supernova explosion. Here we report the discovery of an X-ray shell north of the Galactic micro-quasar SS 433 harboring a stellar-mass black hole spatially associated with radio continuum and polarization emissions, and an HI cloud. Its spectrum can be reproduced by a 1-keV under-ionized plasma, from which the shell is inferred to have been created by a supernova explosion 20-30 kyr ago and its properties constitute evidence for canonical SN explosions to create some black holes. Our analysis precludes other possible origins including heated by jets or blown by disk winds. According to the lower mass limit of the compact object in SS 433, we roughly deduced that the progenitor should be more massive than 25 M$_{\odot}$. The existence of such a young remnant in SS 433 can also lead to new insights into the supercritical accretion in young microquasars and the ${\gamma}$-ray emission of this system. The fallback ejecta may provide accretion materials within tens of thousands of years while the shock of the supernova remnant may play a crucial role in the cosmic ray (re)acceleration.

We developed a Python based framework for astronomical image processing and analysis. Astronomical image loading, normalizing, stacking, and filtering processes represent visible range images from grayscale. Besides, the blending process helps to analyze the image of multiple wavelengths in the visible range. The methods take advantage of include median filtering for noise reduction, unsharp masking for sharpening details, and intensity normalization techniques. The detailed analysis of pixel intensity distributions and applying Gaussian fitting to variations across different wavelength bands. These methods highlight Python as a valuable tool for astronomers.

Type-C quasi-periodic oscillations (QPOs) in black hole X-ray transients typically manifest in the low-hard and hard-intermediate states. This study presents a detailed spectral and temporal analysis of the black hole candidate Swift J1727.8-1613 using NICER observations from August and September 2023, with a focus on the first flare period. The time-averaged spectra, along with the rms and phase-lag spectra of the QPOs, were jointly fitted using the time-dependent Comptonization model \text{vkompthdk} to examine the geometry of the corona during this flare. The results provide a comprehensive view of the QPO, where we detected type-C QPOs with a centroid frequency increasing from 0.32 Hz to 2.63 Hz, while it elevated when it entered the flare state, and its energy spectral properties as they evolved during the first flare period. Correlations between spectral and temporal properties suggest that type-C QPOs are primarily modulated by Lense-Thirring precession. Based on simultaneous radio observations indicating discrete jet ejections, we propose, for the first time, a scenario where the temporarily extended corona contracts vertically from approximately 2714 km to less than 900 km, overlying the inner accretion disc, with a transient jet seemingly being launched. The corona then recovers to nearly 2000 km by the end of the first flare period of Swift J1727.8-1613, rather than undergoing horizontal changes. A phenomenological analysis of the corona scenario during this flare period was also conducted.

We analyse the impact of the expansion of the Universe on the formation of total spectral energy density of radiation in the intergalactic medium. Assuming the same proper thermal spectrum of sources, we show how the expansion of the Universe changes the nature of the energy distribution of the thermal spectrum: a decrease of the energy density in the Wien range and an increase in the Rayleigh--Jeans range with increasing the redshift of the bulk filled by sources. This is due to the cosmological redshift and the growing contribution of large number of distant sources. The numerical estimations also illustrate the main factors that resolve the Olbers' paradox in the expanding Universe: i) the particle horizon, ii) the finiteness of the volume filled by luminous objects, and iii) the cosmological redshift. Applying the obtained expressions to the epoch of reionization made it possible to estimate the concentration of objects of various classes (stars, globular clusters, dwarf galaxies) necessary for complete reionization of hydrogen at $z=6$. It is shown that even a small part of globular clusters or dwarf galaxies with a thermal spectrum of moderate temperature, from those predicted by Press-Schechter formalism and its improvements, is able to completely reionize hydrogen in the intergalactic medium at $z=6$.

In this paper, we investigate chiral gravitational wave (GW) signals generated from inflation to reheating, driven by a parity-violating (PV) term coupled to the inflaton. During inflation, the PV term reduces the sound horizon for right-handed circularly polarized GWs, and amplifies their power spectra relative to left-handed GWs. At CMB scales, these chiral GWs induce BB as well as non-vanishing EB and TB correlations in CMB, which are potentially detectable by LiteBIRD. During reheating, subhorizon modes undergo tachyonic instability, leading to fully circularly polarized GWs with enhanced amplitudes, detectable through the resonant cavity experiment. The absence of backreaction effect of enhanced chiral GWs imposes constraints on the energy scale of the PV term, the inflationary potential, and the reheating history. Our findings highlight the potential of multi-frequency GW experiments to offer a unique probe of the parity violation and early Universe.

The long-term variability study over a range of black hole (BH) mass systems from the microquasars of stellar-mass black holes to the Active Galactic Nuclei (AGNs) of supermassive black holes, in $\gamma$-rays offers new insights into the physics of relativistic jets. In this work, we investigate the $\gamma$-ray variability of 11 AGNs--including 7 blazars, 2 unclassified blazar candidates (BCUs), 1 radio galaxy (RG), and 1 narrow-line Seyfert 1 galaxy (NLS1) as well as 2 microquasars. We apply a stochastic process known as the Damped Random Walk (DRW) to model the $\sim$15 years of Fermi-LAT light curves. The characteristic timescales observed for AGNs are comparable to those in the accretion disc. Interestingly, the timescales observed in the jet emission of microquasars are similar to those of AGNs, suggesting uniform jet properties across the black hole masses. The observed rest-frame timescales of AGNs overlap with both thermal and non-thermal timescales associated with the jet and accretion disk, respectively, suggesting a scaled relationship between $\tau_{DRW}^{rest}$ and black hole mass ($\rm{M_{BH}}$). While the timescales observed for microquasars deviate significantly from this relationship, nonetheless exhibit a scaled $\tau_{DRW}^{rest}-\rm{M_{BH}}$ relationship using $\gamma$-rays specifically. These findings offer new insights into the origin of jets and the processes driving the emission within them. Additionally, this study hints at a new perspective that the relativistic jets' properties or their production mechanisms may be independent of the black hole mass.

The composition of protoplanetary disks, and hence the initial conditions of planet formation, may be strongly influenced by the infall and thermal processing of material during the protostellar phase. Composition of dust and ice in protostellar envelopes, shaped by energetic processes driven by the protostar, serves as the fundamental building material for planets and complex organic molecules. As part of the JWST GO program, "Investigating Protostellar Accretion" (IPA), we observed an intermediate-mass protostar HOPS 370 (OMC2-FIR3) using NIRSpec/IFU and MIRI/MRS. This study presents the gas and ice phase chemical inventory revealed with the JWST in the spectral range of $\sim$2.9 to 28 $\mu$m and explores the spatial variation of volatile ice species in the protostellar envelope. We find evidence for thermal processing of ice species throughout the inner envelope. We present the first high-spatial resolution ($\sim 80$ au) maps of key volatile ice species H$_{2}$O, CO$_{2}$, $^{13}$CO$_2$, CO, and OCN$^-$, which reveal a highly structured and inhomogeneous density distribution of the protostellar envelope, with a deficiency of ice column density that coincides with the jet/outflow shocked knots. Further, we observe high relative crystallinity of H$_{2}$O ice around the shocked knot seen in the H$_2$ and OH wind/outflow, which can be explained by a lack of outer colder material in the envelope along the line of sight due to the irregular structure of the envelope. These observations show clear evidence of thermal processing of the ices in the inner envelope, close to the outflow cavity walls, heated by the luminous protostar.

Globular clusters (GCs) are extremely intriguing systems that help in reconstructing the assembly of the Milky Way via the characterization of their chemo-chrono-dynamical properties. In this study, we use high-resolution spectroscopic archival data from UVES at VLT and UVES-FLAMES at VLT to compare the chemistry of GCs dynamically tagged as either Galactic (NGC 6218, NGC 6522 and NGC 6626) or accreted from distinct merging events (NGC 362 and NGC 1261 from Gaia-Sausage-Enceladus, Ruprecht 106 from the Helmi Streams) in the metallicity regime where abundance patterns of field stars with different origin effectively separate ($-1.3 \le$ [Fe/H] $\le -1.0$ dex). We find remarkable similarities in the abundances of the two Gaia-Sausage-Enceladus GCs across all chemical elements. They both display depletion in the $\alpha$-elements (Mg, Si and Ca) and statistically significant differences in Zn and Eu compared to in situ GCs. Additionally, we confirm that Ruprecht 106 exhibits a completely different chemical makeup compared to the other target clusters, being underabundant in all chemical elements. This demonstrates that when high precision is achieved, the abundances of certain chemical elements not only can efficiently separate in situ from accreted GCs, but can also distinguish among GCs born in different progenitor galaxies. In the end, we investigate the possible origin of the chemical peculiarity of Ruprecht 106. Given that its abundances do not match the chemical patterns of field stars associated to its most likely parent galaxy (i.e., the Helmi Streams), especially being depleted in the $\alpha$-elements, we interpret Ruprecht 106 as originating in a less massive galaxy compared to the progenitor of the Helmi Streams.

The research focuses on determining the metallicity ([Fe/H]) predicted in the solar twin stars by using various regression modeling techniques which are, Random Forest, Linear Regression, Decision Tree, Support Vector, and Gradient Boosting. The data set that is taken into account here includes Stellar parameters and chemical abundances derived from a high-accuracy abundance catalog of solar twins from the GALAH survey. To overcome the missing values, intensive preprocessing techniques involving, imputation are done. Each model will subjected to training using different critical observables, which include, Mean Squared Error(MSE), Mean Absolute Error(MAE), Root Mean Squared Error(RMSE), and R-squared. Modeling is done by using, different feature sets like temperature: effective temperature(Teff), surface gravity: log g of 14-chemical-abundances namely, (([Na/Fe], [Mg/Fe], [Al/Fe], [Si/Fe], [Ca/Fe], [Sc/Fe], [Ti/Fe], [Cr/Fe], [Mn/Fe], [Ni/Fe], [Cu/Fe], [Zn/Fe], [Y/Fe], [Ba/Fe])). The target variable considered is the metallicity ([Fe/H]). The findings indicate that the Random Forest model achieved the highest accuracy, with an MSE of 0.001628 and an R-squared value of 0.9266. The results highlight the efficacy of ensemble methods in handling complex datasets with high dimensionality. Additionally, this study underscores the importance of selecting appropriate regression models for astronomical data analysis, providing a foundation for future research in predicting stellar properties with machine learning techniques.

This study explores a relationship between the CO luminosity-full width at half-maximum linewidth linear relation (i.e. the CO LFR) and mean galaxy property of the local star-forming galaxy sample in the xCOLDGASS data base, via a mathematical statement. The whole data base galaxies were separated into two subsamples based on their stellar masses and redshifts, being a help to examine the dependence issue of the CO LFR. Selecting the galaxy data with a stringent requirement was also implemented in order to assure the validly of the CO LFR. An algorithm of the linear regression was conducted with the data of the subsample. An assessment about the linear correlation manifested a valid CO LFR occurs in the selected galaxy of the subsample, and the intercept of the CO LFR may be related with the mean galaxy properties such as the molecular gas fraction and galaxy size. For the finding on the intercept of the CO LFR, we aligned that intercept with those galaxy properties via the involvement of a $\psi$ parameter. On evaluating the $\psi$ value with our local star-forming galaxy sample, we numerically determined a relationship between the statistical result and the galaxy property in a different stellar mass range. It also shows a possible method on estimating galaxy property.

A recent study on the spectral energy distribution (SED) of AGN combined unobscured X-ray sources from the eROSITA eFEDS Survey with high quality optical imaging from Subaru's Hyper Suprime-Cam (HSC). The HSC data enabled accurate host galaxy subtraction as well as giving a uniform black hole mass estimator from the stellar mass. The resulting stacked optical/X-ray SEDs for black holes at fixed mass show a dramatic transition, where the dominating disc component in bright AGN evaporates into an X-ray hot plasma below $L/L_{\rm Edd}\sim 0.01$. The models fit to these datasets predicted the largest change in SED in the rest frame UV ($< 3000\,Å$), but this waveband was not included in the original study. Here we use archival $u$-band and UV photometry to extend the SEDs into this range, and confirm the UV is indeed intrinsically faint in AGN below $L/L_{\rm Edd}\sim 0.01$ as predicted. This dramatic drop in UV photo-ionising flux is also seen from its effect on the broad emission lines. We stack the recently released SDSS DR18 optical spectra for this sample, and show that the broad H$\beta$ line disappears along with the UV bright component at $L/L_{\rm Edd}\sim 0.01$. This shows that there is a population of unobscured, X-ray bright, UV faint AGN which lack broad emission lines (true type 2 Seyferts).

Star formation rates (SFRs) are a crucial observational tracer of galaxy formation and evolution. Spectroscopy, which is expensive, is traditionally used to estimate SFRs. This study tests the possibility of inferring SFRs of large samples of galaxies from only photometric data, using state-of-the-art machine learning and deep learning algorithms. The dataset adopted in this work is the one collected by Delli Veneri et al. (2019): it includes photometric data of more than 27 million galaxies coming from the Sloan Digital Sky Survey Data Release 7 (SDSS-DR7). The algorithms we implemented and tested for comparing the performances include Linear Regression, Long Short-Term Memory (LSTM) networks, Support Vector Regression (SVR), Random Forest Regressor, Decision Tree Regressor, Gradient Boosting Regressor, and classical deep learning models. Our results mention that the Linear Regression model predicted an impressive accuracy of 98.97 percent as measured by the Mean Absolute Error (MAE), demonstrating that machine-learning approaches can be effective when it comes to photometric SFR estimation. Besides, the paper also reported the results for other intelligent algorithms, which predicted the SFRs, providing a detailed comparison of the performance of different machine learning algorithms in the photometric SFR estimation. This study not only shows the estimated SFR from photometric data is promising but also opens a door toward the application of machine learning and deep learning in astrophysics.

Type II supernovae (SNeII) mark the endpoint in the lives of hydrogen-rich massive stars. Their large explosion energies and luminosities allow us to measure distances, metallicities, and star formation rates into the distant Universe. To fully exploit their use in answering different astrophysical problems, high-quality low-redshift data sets are required. Such samples are vital to understand the physics of SNeII, but also to serve as calibrators for distinct - and often lower-quality - samples. We present uBgVri optical and YJH near-infrared (NIR) photometry for 94 low-redshift SNeII observed by the Carnegie Supernova Project (CSP). A total of 9817 optical and 1872 NIR photometric data points are released, leading to a sample of high-quality SNII light curves during the first ~150 days post explosion on a well-calibrated photometric system. The sample is presented and its properties are analysed and discussed through comparison to literature events. We also focus on individual SNeII as examples of classically defined subtypes and outlier objects. Making a cut in the plateau decline rate of our sample (s2), a new subsample of fast-declining SNeII is presented. The sample has a median redshift of 0.015, with the nearest event at 0.001 and the most distant at 0.07. At optical wavelengths (V), the sample has a median cadence of 4.7 days over the course of a median coverage of 80 days. In the NIR (J), the median cadence is 7.2 days over the course of 59 days. The fast-declining subsample is more luminous than the full sample and shows shorter plateau phases. Of the non-standard SNeII highlighted, SN2009A particularly stands out with a steeply declining then rising light curve, together with what appears to be two superimposed P-Cygni profiles of H-alpha in its spectra. We outline the significant utility of these data, and finally provide an outlook of future SNII science.

Context: PKS 0903-57 is a little-studied gamma-ray blazar which has recently attracted considerable interest due to the strong flaring episodes observed since 2020 in HE (100 MeV < E < 100 GeV) and VHE (100 GeV < E < 10 TeV) gamma-rays. Its nature and properties are still not well determined. In particular, it is unclear whether PKS 0903-57 is a BL Lac or a Flat Spectrum Radio Quasar (FSRQ), while its redshift estimation relies on a possibly misassociated low signal-to-noise spectrum. Aim: We aim to reliably measure the redshift of the blazar and to determine its spectral type and luminosity in the optical range. Methods: We performed spectroscopy of the optical counterpart of the blazar using the South African Large Telescope (SALT) and the Very Large Telescope (VLT) and monitored it photometrically with the Rapid Eye Mount (REM) telescope. Results: We firmly measured the redshift of the blazar as z= 0.2621 +/- 0.0006 thanks to the detection of five narrow optical lines. The detection of a symmetric broad Halpha line with Full Width at Half Maximum (FWHM) of 4020 +/- 30 km/s together with a jet-dominated continuum leads us to classify it as a FSRQ. Finally, we detected with high significance a redshift offset (about 1500 km/s) between the broad line and the host. This is the first time that such an offset is unequivocally detected in a VHE blazar, possibly pointing to a very peculiar accretion configuration, a merging system, or a recoiling Black Hole.

The accurate flux calibration of observational data is vital for astrophysics and cosmology because absolute flux uncertainties of stellar standards propagate into scientific results. With the ever higher precision achieved by telescopic missions (e.g. JWST) in the infrared (IR), suitable calibrators are required for this regime. The basis of the Hubble Space Telescope (HST) flux scale is defined by model fits of three hot (Teff > 30000 K) hydrogen-atmosphere (DA) white dwarfs, which achieve an accuracy better than 1 per cent at optical wavelengths but falls below this level in the IR range. We present a network of 17 cooler DA white dwarfs with Teff < 20000 K as spectrophotometric flux standards that are equally, if not more, accurate at IR wavelengths. Cooler white dwarfs do not suffer from non-local thermal equilibrium (NLTE) effects in continuum flux or from UV metal line blanketing, have a larger sky density, are generally closer to Earth with little or negligible interstellar reddening, and have energy distributions peaking in the optical or near-IR. Using the latest grid of DA LTE atmosphere models with three-dimensional (3D) convection, the observed Space Telescope Imaging Spectrometer (STIS) and Wide Field Camera three (WFC3) fluxes of our network are accurate to 3 per cent over most of the range 1450 - 16000 AA, with a median standard deviation of 1.41 per cent. Fitting the HST STIS and WFC3 white dwarf SEDs and Balmer lines independently yields SEDs that agree within 3$\sigma$, which demonstrates the precision of the models for our network.

Producing optimized and accurate transmission spectra of exoplanets from telescope data has traditionally been a manual and labor-intensive procedure. Here we present the results of the first attempt to improve and standardize this procedure using artificial intelligence (AI) based processing of light curves and spectroscopic data from transiting exoplanets observed with the Hubble Space Telescope's (HST) Wide Field Camera 3 (WFC3) instrument. We implement an AI-based parameter optimizer that autonomously operates the Eureka pipeline to produce homogeneous transmission spectra of publicly available HST WFC3 datasets, spanning exoplanet types from hot Jupiters to sub-Neptunes. Surveying 43 exoplanets with temperatures between 280 and 2580 Kelvin, we confirm modeled relationships between the amplitude of the water band at 1.4um in hot Jupiters and their equilibrium temperatures. We also identify a similar, novel trend in Neptune/sub-Neptune atmospheres, but shifted to cooler temperatures. Excitingly, a planet mass versus equilibrium temperature diagram reveals a "Clear Sky Corridor," where planets between 700 and 1700 Kelvin (depending on the mass) show stronger 1.4um H2O band measurements. This novel trend points to metallicity as a potentially important driver of aerosol formation. As we unveil and include these new discoveries into our understanding of aerosol formation, we enter a thrilling future for the study of exoplanet atmospheres. With HST sculpting this foundational understanding for aerosol formation in various exoplanet types, ranging from Jupiters to sub-Neptunes, we present a compelling platform for the James Webb Space Telescope (JWST) to discover similar atmospheric trends for more planets across a broader wavelength range.

The inner and outer cores of neutron stars are believed to contain type-I and -II proton superconductors, respectively. The type-I superconductor exists in an intermediate state, comprising macroscopic flux-free and flux-containing regions, while the type-II superconductor is flux-free, except for microscopic, quantized flux tubes. Here, we show that the inner and outer cores are coupled magnetically, when the macroscopic flux tubes subdivide dendritically into quantized flux tubes, a phenomenon called flux branching. An important implication is that up to $\sim 10^{12} (r_1/10^6 \, {\rm cm}) \, {\rm erg}$ of energy are required to separate a quantized flux tube from its progenitor macroscopic flux tube, where $r_1$ is the length of the macroscopic flux tube. Approximating the normal-superconducting boundary as sharp, we calculate the magnetic coupling energy between a quantized and macroscopic flux tube due to flux branching as a function of, $f_1$, the radius of the type-I inner core divided by the radius of the type-II outer core. Strong coupling delays magnetic field decay in the type-II superconductor. For an idealised inner core containing only a type-I proton superconductor and poloidal flux, and in the absence of ambipolar diffusion and diamagnetic screening, the low magnetic moments ($\lesssim 10^{27} \, {\rm G \, cm^3}$) of recycled pulsars imply $f_1 \lesssim 10^{-1.5}$.

Cosmological simulations indicate that nearly half of the baryons in the nearby Universe are in the warm-hot intergalactic medium (WHIM) phase, with about half of which residing in cosmic filaments. Recent observational studies using stacked survey data and deep exposures of galaxy cluster outskirts have detected soft X-ray excess associated with optically identified filaments. However, the physical characteristics of WHIM in filaments remain largely undetermined due to the lack of direct spectral diagnostics. In this work, we aim to select appropriate targets for WHIM characterization through pointing observations with the future Hot Universe Baryon Surveyor (HUBS) mission, which is designed with eV level energy resolution in the 0.1-2.0 keV band and a 1 square degree field-of-view. We built a sample of 1577 inter-cluster filaments based on the first eROSITA All-Sky Survey (eRASS1) supercluster catalog and estimated their soft X-ray emission, and used their modeled geometrical properties and oxygen line intensities to select four most appropriate candidate targets for HUBS observations. By simulating and analyzing their mock observations, we demonstrated that with 200 ks HUBS exposure for each candidate, the gas properties of individual filaments can be accurately determined, with the temperature constrained to +-0.01 keV, metallicity constrained to < +-0.03 solar, and density constrained to < +-10%. Elemental abundance of O, Ne, Mg, and Fe can be measured separately, providing unprecedented insights into the chemical history of the filament gas. We also showed that direct mapping of the WHIM distribution is promising with narrow-band imaging of the O viii line. Our work forecasts that next-generation X-ray missions such as HUBS will provide substantial improvement in our understanding of the physical status and evolution history of the diffuse WHIM gas in cosmic large-scale structure.

The central theme of this thesis work is to explore the possibilities of spiral arm formations from instabilities formed inside the central region of disc galaxies. These instabilities originate from the central baryonic feedback and have many prospects regarding the evolution of disc galaxies. They can trigger the gravitational collapse inside the dense molecular clouds that lead to the formation of stars under suitable astrophysical circumstances. In the present work, the role of parameters like the molecular cloud's magnetic field, rotation, etc., has been investigated behind this explosion-triggered star formation process with the help of Jeans instability analysis. From this study, our essential observation is that the formation of star clusters is favoured by a strong magnetic field ($\sim 10 \; \mu$G), and the effect is enhanced at a more considerable distance from the centre. Again, this instability also contributes to the formation of stellar bars. This dense rotating component may drive out the chaotic stellar orbits from the disc through its two ends like a propeller. This process has been modelled in the thesis work from the viewpoint of chaotic scattering in open Hamiltonian systems. This analysis concludes that this bar-driven chaotic motion (or simply escaping motion) may lead to the forming of spiral arms or inner disc rings, depending on the bar strength. Our study also found that, compared to NFW dark haloes, the oblate dark haloes offer a more cohesive evolutionary framework for generating bar-driven escape structures in giant spiral and dwarf galaxies. Moreover, the formation of spiral arms via bar-driven escaping motion is only encouraged in galaxies with NFW dark haloes if they have highly energetic centres, like active galaxies.

Context. The gravitational lens system SDSS J1004+4112 was the first known example of a quasar lensed by a galaxy cluster. The interest in this system has been renewed following the publication of r-band light curves spanning 14.5 years and the determination of the time delays between the four brightest quasar images. Aims. We constrained the quasar accretion disk size and the fraction of the lens mass in stars using the signature of microlensing in the quasar image light curves. Methods. We built the six possible histograms of microlensing magnitude differences between the four quasar images and compared them with simulated model histograms, using a $\chi^2$ test to infer the model parameters. Results. We infer a quasar disk half-light radius of $R_{1/2}=(0.70\pm0.04)\, R_E=(6.4\pm0.4) \sqrt{M/0.3M_{\odot}}$ light-days at 2407Å in the rest frame and stellar mass fractions at the quasar image positions of $\alpha_A>0.059$, $\alpha_B=0.056^{+0.021}_{-0.027}$, $\alpha_C=0.030^{+0.031}_{-0.021}$, and $\alpha_D=0.072^{+0.034}_{-0.016}$. Conclusions. The inferred disk size is broadly compatible with most previous estimates, and the stellar mass fractions are within the expected ranges for galaxy clusters. In the region where image C lies, the stellar mass fraction is compatible with a stellar contribution from the brightest cluster galaxy, galaxy cluster members, and intracluster light, but the values at images B, D, and especially A are slightly larger, possibly suggesting the presence of extra stellar components.

I conducted photometric observations of the cataclysmic variable LAMOST J035913.61+405035.0 and discovered previously unknown eclipses. During these observations, I recorded 14 eclipses over two groups of nights separated by 13 months. I accurately determined the orbital period of the system to be Porb=0.22834385+\-0.00000021 d. For the eclipses, I derived an ephemeris which is valid for a long time and suitable for studying changes in the orbital period. The out-of-eclipse magnitude of the star varied between 15.32(+\-0.02) and 17.25(+\-0.08) mag. As the brightness decreased, the eclipses became deeper and narrower. The average depth of eclipses was 1.35(+\-0.10) mag, and the average width at half-depth was 16.9(+\-0.7) min. I estimated the range of possible orbital inclinations to be between 72.8 degr and 76.0 degr, and the range of average absolute V-band magnitudes of the disc to be between 5.16(+\-0.15) and 5.44(+\-0.15) mag. Although based on the light curve from the ZTF survey, LAMOST J035913.61+405035.0 showed only small outbursts with amplitudes below 1.5 mag, it should be classified as a dwarf nova because the average disc brightness and mass transfer rate were below the limit of thermal instability. However, there have been no significant outbursts in the ZTF light curve over the past 1.6 yr. Instead, a gradual decrease in brightness lasting 120 d suggests that this object may occasionally become a nova-like variable of the VY Scl type.

Nongravitational accelerations in the absence of observed activity have recently been identified on NEOs, opening the question of the prevalence of anisotropic mass-loss in the near-Earth environment. Motivated by the necessity of nongravitational accelerations to identify 2010 VL$_{65}$ and 2021 UA$_{12}$ as a single object, we investigate the problem of linking separate apparitions in the presence of nongravitational perturbations. We find that nongravitational accelerations on the order of $10^{-9}$ au/d$^2$ can lead to a change in plane-of-sky positions of $\sim10^3$ arcsec between apparitions. Moreover, we inject synthetic tracklets of hypothetical nongravitationally-accelerating NEOs into the Minor Planet Center orbit identification algorithms. We find that at large nongravitational accelerations ($|A_i|\geq10^{-8}$ au/d$^2$) these algorithms fail to link a significant fraction of these tracklets. We further show that if orbits can be determined for both apparitions, the tracklets will be linked regardless of nongravitational accelerations, although they may be linked to multiple objects. In order to aid in the identification and linkage of nongravitationally accelerating objects, we propose and test a new methodology to search for unlinked pairs. When applied to the current census of NEOs, we recover the previously identified case but identify no new linkages. We conclude that current linking algorithms are generally robust to nongravitational accelerations, but objects with large nongravitational accelerations may potentially be missed. While current algorithms are well-positioned for the anticipated increase in the census population from future survey missions, it may be possible to find objects with large nongravitational accelerations hidden in isolated tracklet pairs.

Modeling based on differentiable programming holds great promise for astronomy, as it can employ techniques such as Hamiltonian Monte Carlo, gradient-based optimization, and other machine learning techniques. This new programming paradigm has motivated us to develop the first auto-differentiable spectrum model of exoplanets and brown dwarfs, ExoJAX (Kawahara et al. 2022). ExoJAX is designed to directly calculate cross-sections as functions of temperature and pressure, rather than interpolating tabulated data, to minimize errors in high-dispersion spectra modeling. However, its application was primarily proof-of-concept and limited to narrowband high-dispersion emission spectroscopy. In this paper, we have enhanced the differentiable opacity calculation using a new fast and memory-efficient algorithm, and have developed differentiable radiative transfer schemes, including emission, transmission, and reflection spectroscopy. These enhancements significantly expand the range of applications, as demonstrated through actual atmospheric retrievals: high-dispersion emission spectra of the brown dwarf GL229 B, medium-dispersion transmission spectra of the hot Saturn WASP-39 b from JWST, and high-dispersion reflection spectra of Jupiter. We obtained a C/O ratio for GL229 B consistent with its host star, constrained WASP-39 b's radial velocity from molecular fine structures at original resolution ($R \sim 3,000$), and estimated Jupiter's metallicity consistent with previous studies.

The exoplanet archive is an incredible resource of information on the properties of discovered extrasolar planets, but statistical analysis has been limited by the number of missing values. One of the most informative bulk properties is planet mass, which is particularly challenging to measure with more than 70\% of discovered planets with no measured value. We compare the capabilities of five different machine learning algorithms that can utilize multidimensional incomplete datasets to estimate missing properties for imputing planet mass. The results are compared when using a partial subset of the archive with a complete set of six planet properties, and where all planet discoveries are leveraged in an incomplete set of six and eight planet properties. We find that imputation results improve with more data even when the additional data is incomplete, and allows a mass prediction for any planet regardless of which properties are known. Our favored algorithm is the newly developed $k$NN$\times$KDE, which can return a probability distribution for the imputed properties. The shape of this distribution can indicate the algorithm's level of confidence, and also inform on the underlying demographics of the exoplanet population. We demonstrate how the distributions can be interpreted with a series of examples for planets where the discovery was made with either the transit method, or radial velocity method. Finally, we test the generative capability of the $k$NN$\times$KDE to create a large synthetic population of planets based on the archive, and identify potential categories of planets from groups of properties in the multidimensional space. All codes are Open Source.

We use James Webb Space Telescope (JWST) Mid-Infrared Instrument (MIRI) medium-resolution spectrometer (MRS) observations of UGC 8782, CGCG 012-070 and NGC 3884 to investigate the origin of the H$_2$ emission. These three nearby AGN hosts are known to present H$_2$ emission excess relative to star-forming galaxies, as traced by the H$_2$ S(3)/PAH$_{\rm 11.3\mu m}$ line ratio. For every spaxel, we also measure the velocity width ($W_{\rm 80}$) of H$_2$ S(3). We find that the distribution of H$_2$ in the space of these parameters - H$_2$/PAH and its velocity width - is bimodal: one cluster of points shows approximately constant values of $W_{\rm 80}$, while the other cluster exhibits a strong correlation between $W_{\rm 80}$ and H$_2$/PAH. We estimated the temperature of the H$_2$ gas assuming a power-law distribution and find flatter distributions in regions where a correlation between $W_{\rm 80}$ and H$_2$ S(3)/PAH$_{\rm 11.3\mu m}$ is observed. Additionally, we observed a correlation between the [Fe II]$_{\rm 5.34 \mu m}$ (a known shock tracer) and the H$_2$ emission. This indicates that the excess H$_2$ emission excess is associated to shock heating of the gas, generated by outflows or by the interaction of the radio jet with the ambient gas.

We introduce OneCovariance, an open-source software designed to accurately compute covariance matrices for an arbitrary set of two-point summary statistics across a variety of large-scale structure tracers. Utilising the halo model, we estimate the statistical properties of matter and biased tracer fields, incorporating all Gaussian, non-Gaussian, and super-sample covariance terms. The flexible configuration permits user-specific parameters, such as the complexity of survey geometry, the halo occupation distribution employed to define each galaxy sample, or the form of the real-space and/or Fourier space statistics to be analysed. We illustrate the capabilities of OneCovariance within the context of a cosmic shear analysis of the final data release of the Kilo-Degree Survey (KiDS-Legacy). Upon comparing our estimated covariance with measurements from mock data and calculations from independent software, we ascertain that OneCovariance achieves accuracy at the per cent level. When assessing the impact of ignoring complex survey geometry in the cosmic shear covariance computation, we discover misestimations at approximately the $10\%$ level for cosmic variance terms. Nonetheless, these discrepancies do not significantly affect the KiDS-Legacy recovery of cosmological parameters. We derive the cross-covariance between real-space correlation functions, bandpowers, and COSEBIs, facilitating future consistency tests among these three cosmic shear statistics. Additionally, we calculate the covariance matrix of photometric-spectroscopic galaxy clustering measurements, validating Jackknife covariance estimates for calibrating KiDS-Legacy redshift distributions. The OneCovariance can be found on github Hub together with a comprehensive documentation and examples.

Feedback processes in galaxies dictate their structure and evolution. Baryons can be cycled through stars, which inject energy into the interstellar medium (ISM) in supernova explosions, fueling multiphase galactic winds. Cosmic rays (CRs) accelerated at supernova remnants are an important component of feedback. CRs can effectively contribute to wind driving; however, their impact heavily depends on the assumed CR transport model. We run high-resolution "tallbox" simulations of a patch of a galactic disk using the moving mesh magnetohydrodynamics code AREPO, including varied CR implementations and the CRISP non-equilibrium thermochemistry model. We characterize the impact of CR feedback on star formation and multiphase outflows. While CR-driven winds are able to supply energy to a global-scale wind, a purely thermal wind loses most of its energy by the time it reaches 3 kpc above the disk midplane. We further find that the adopted CR transport model significantly affects the steady-state of the wind. In the model with CR advection, streaming, diffusion, and nonlinear Landau damping, CRs provide very strong feedback. Additionally accounting for ion-neutral damping (IND) decouples CRs from the cold ISM, which reduces the impact of CRs on the star formation rate. Nevertheless, CRs in this most realistic model are able to accelerate warm gas and levitate cool gas in the wind but have little effect on cold gas and hot gas. This model displays moderate mass loading and significant CR energy loading, demonstrating that IND does not prevent CRs from providing effective feedback.

We study local magnetohydrodynamical (MHD) instabilities of differential rotation in magnetised, stably-stratified regions of stars and planets using a Cartesian Boussinesq model. We consider arbitrary latitudes and general shears (with gravity direction misaligned from this by an angle $\phi$), to model radial ($\phi=0$), latitudinal ($\phi=\pm 90^\circ$), and mixed differential rotations, and study both non-diffusive (including magnetorotational, MRI, and Solberg-Høiland instabilities) and diffusive instabilities (including Goldreich-Schubert-Fricke, GSF, and MRI with diffusion). These instabilities could drive turbulent transport and mixing in radiative regions, including the solar tachocline and the cores of red giant stars, but their dynamics are incompletely understood. We revisit linear axisymmetric instabilities with and without diffusion and analyse their properties in the presence of magnetic fields, including deriving stability criteria and computing growth rates, wavevectors and energetics, both analytically and numerically. We present a more comprehensive analysis of axisymmetric local instabilities than prior work, exploring arbitrary differential rotations and diffusive processes. The presence of a magnetic field leads to stability criteria depending upon angular velocity rather than angular momentum gradients. We find MRI operates for much weaker differential rotations than the hydrodynamic GSF instability, and that it typically prefers much larger lengthscales, while the GSF instability is impeded by realistic strength magnetic fields. We anticipate MRI to be more important for turbulent transport in the solar tachocline than the GSF instability when $\phi>0$ in the northern (and vice versa in the southern) hemisphere, though the latter could operate just below the convection zone when MRI is absent for $\phi<0$.

The first detailed photometric and spectroscopic analysis of the G-type eclipsing binary KM UMa is presented, which indicates that the system is a short-period detached eclipsing binary. The radial velocity curves were calculated using the cross-correlation function method based on Large Sky Area Multi-Object Fiber Spectroscopic Telescope, Sloan Digital Sky Survey, and our observations, which determined the mass ratio as $q=0.45\ (\pm0.04)$. Based on the light curves from the Transiting Exoplanet Survey Satellite, other survey data, and our multiband observations, the positive and negative O'Connell effects have been detected evolving gradually and alternately over the last 20 yr, which can be explained by the presence of spots on the primary component. A superflare event was detected in the SuperWASP data on 2007 February 28, further indicating that KM UMa is a very active system. We calculated its energy to be $5\times10^{34}$ erg by assuming it occurred on the primary star. Utilizing hundreds of medium-resolution spectra and one low-resolution spectrum, the equivalent width variations of the $H_{\alpha}$ line were calculated, indicating the presence of a 5.21 ($\pm0.67$) yr magnetic activity cycle. The orbital period variations were analyzed using the O-C method, detecting a long-term decrease superimposed with a periodic variation. The amplitude of the cyclic variation is $0.01124\ (\pm0.00004)$ day, with a period of $33.66\ (\pm 0.0012)$ yr, which exceeds the 5.21 yr activity cycle, suggesting that this is more likely attributable to the light travel time effect of a third body. Simultaneously, a visual companion has been detected based on the Gaia astrometric data, indicating that KM UMa is actually in a 2+1+1 hierarchical quadruple system.

We have carried out a detailed study of the GRB photospheric emission model predicting a quasi-blackbody spectrum slightly broader than a Planck function. This model was suggested within the relativistic fireball dynamics for interpreting a still not well understood thermal component in the GRB prompt emission, recently observed by the GBM on board the Fermi space telescope. We propose a Monte Carlo (M C) code for elucidating the observed spectrum, the outflow dynamics and its geometry for a basic and a structured plasma jets whose parameters are implemented. The code involves a simulation part describing the photon propagation assuming an unpolarized, non-dissipative relativistic outflow and a data analysis part for exploring main photospheric emission properties such as the energy, arrival time and observed flux of the simulated seed photons and the photospheric radius. Computing the latter two observables by numerical integration, we obtained values very concordant with the M C simulated results. Fitting Band functions to the photon spectra generated by this method, we derived best-fit values of the photon indices matching well those featuring the observed spectra for most typical GRBs, but corresponding to fit functions inconciliable with blackbody spectral shapes. Various derived results are reported, compared to previous ones and discussed. They show to be very sensitive to the structure of the Lorentz factor that plays a crucial role in determining the presence and strength of geometrical effects. The latter manifest themselves by large broadenings of the simulated spectra featured by multiple peak energies consistently with GRB observations. They are assumed, with multiple Compton scattering, to produce bumps pointed out at very low photon energies. Finally, developments of this work are put into perspective.

The intensity of the extragalactic background (EBL), the accumulated optical and infrared emissions since the first stars, is the subject of a decades-long tension in the optical band. These photons form a target field that attenuates the $\gamma$-ray flux from extragalactic sources. This paper reports the first $\gamma$-ray measurement of the EBL spectrum at $z=0$ that is purely parametric and independent of EBL evolution with redshift, over a wavelength range from $0.18$ to $120\,\mu$m. Our method extracts the EBL absorption imprint on more than 260 archival TeV spectra from the STeVECat catalog, by marginalizing nuisance parameters describing the intrinsic emission and instrumental uncertainties. We report an intensity at 600 nm of $6.9 \pm 1.9$ nW m$^{-2}$ sr$^{-1}\,\times\, h_{70}$, which is indistinguishable from the intensity derived from integrated galaxy light (IGL) and compatible with direct measurements taken beyond Pluto's orbit. We exclude with $95\,\%$ confidence diffuse contributions to the EBL with an intensity relative to the IGL, $f_\mathrm{diff}$, greater than $20\,\%$ and provide a measurement of the expansion rate of the universe at $z=0$, $H_0 = 67^{+7}_{-6}$ km s$^{-1}$ Mpc$^{-1}\,\times\, (1+f_\mathrm{diff})$, which is EBL-model independent. IGL, direct and $\gamma$-ray measurements agree on the EBL intensity in the optical band, finally reaching a cosmological optical convergence.

Magnetic fields have been shown both observationally and through theoretical work to be an important factor in the formation of protostars and their accretion disks. Accurate modelling of the evolution of the magnetic field in low-ionization molecular cloud cores requires the inclusion of non-ideal magnetohydrodynamics (MHD) processes, specifically Ohmic and ambipolar diffusion and the Hall effect. These have a profound influence on the efficiency of magnetic removal of angular momentum from protostellar disks and simulations that include them can avoid the `magnetic-braking catastrophe' in which disks are not able to form. However, the impact of the Hall effect, in particular, is complex and remains poorly studied. In this work, we perform a large suite of simulations of the collapse of cloud cores to protostars with several non-ideal MHD chemistry models and initial core geometries using the moving-mesh code {\small AREPO}. We find that the efficiency of angular momentum removal is significantly reduced with respect to ideal MHD, in line with previous results. The Hall effect has a varied influence on the evolution of the disk which depends on the initial orientation of the magnetic field. This extends to the outflows seen in a subset of the models, where this effect can act to enhance or suppress them and open up new outflow channels. We conclude, in agreement with a subset of the previous literature, that the Hall effect is the dominant non-ideal MHD process in some collapse scenarios and thus should be included in simulations of protostellar disk formation.

Accurately measuring magnetic field strength in the interstellar medium, including giant molecular clouds (GMCs), remains a significant challenge. We present a machine learning approach using Denoising Diffusion Probabilistic Models (DDPMs) to estimate magnetic field strength from synthetic observables such as column density, dust continuum polarization vector orientation angles, and line-of-sight (LOS) nonthermal velocity dispersion. We trained three versions of the DDPM model: the 1-channel DDPM (using only column density), the 2-channel DDPM (incorporating both column density and polarization angles), and the 3-channel DDPM (which combines column density, polarization angles, and LOS nonthermal velocity dispersion). We assessed the models on both synthetic test samples and new simulation data that were outside the training set's distribution. The 3-channel DDPM consistently outperformed both the other DDPM variants and the power-law fitting approach based on column density alone, demonstrating its robustness in handling previously unseen data. Additionally, we compared the performance of the Davis-Chandrasekhar-Fermi (DCF) methods, both classical and modified, to the DDPM predictions. The classical DCF method overestimated the magnetic field strength by approximately an order of magnitude. Although the modified DCF method showed improvement over the classical version, it still fell short of the precision achieved by the 3-channel DDPM.

A stellar-mass black hole (BH) surrounded by a neutrino-dominated accretion flow (NDAF) is generally considered to be the central engine of gamma-ray bursts (GRBs). Neutrinos escaping from the disk will annihilate out of the disk to produce the fireball that could power GRBs with blackbody (BB) components. The initial GRB jet power and fireball launch radius are related to the annihilation luminosity and annihilation height of the NDAFs, respectively. In this paper, we collect 7 GRBs with known redshifts and identified BB components to test whether the NDAF model works. We find that, in most cases, the values of the accretion rates and the central BH properties are all in the reasonable range, suggesting that these BB components indeed originate from the neutrino annihilation process.

We propose a new predictive theory for the analysis of common envelope (CE) events which incorporates the effects of relevant hydrodynamical processes into a simple analytical framework. We introduce the ejection and dynamical parameters $\xi$ and $\beta$, which define if envelope ejection is energetically or hydrodynamically favorable, respectively, during CE inspiral. When combined, these parameters offer a detailed narrative of how inspiral begins, proceeds, and ends that is consistent with preliminary comparisons to 3D hydrodynamical models. This physically-motivated framework impacts predictions for CE outcomes, especially for systems that have energy excess, and offers promise as a potential alternative for the treatment of CE in binary population synthesis.

The \textit{memory burden} effect, stating that the amount of information stored within a system contributes to its stabilization, is particularly significant in systems with a high capacity for information storage such as black holes. In these systems, the evaporation process is halted, at the latest, after approximately half of the black hole's initial mass has been radiated away. Consequently, light primordial black holes (PBHs) of mass $m_{\rm PBH} \lesssim 10^{15}\,$g, which are expected to have fully evaporated by present time, may remain viable candidates for dark matter (DM). In this scenario, we demonstrate that their mergers would continue to occur today, leading to the formation of ``young'' black holes that resume evaporating, producing ultrahigh-energy cosmic rays detectable by current experiments. The emission spectrum would be thermal in all Standard Model particle species, offering a clear and distinguishable signature. Current measurements of the isotropic neutrino flux at Earth are in tension with light PBHs as DM candidates within the mass range $7\times10^3\lesssim m_{\rm PBH}/{\rm g}\lesssim 4\times 10^8$, if neutrinos are of Majorana nature. We also discuss the potential for refining these constraints through gamma-ray and cosmic-ray observations, as well as gravitational wave detections.

We used FAST to conduct deep HI imaging of the entire M 106 group region, and have discovered a few new HI filaments and clouds. Three HI clouds/filaments are found in a region connecting DDO 120 and NGC 4288, indicating an interaction between these two galaxies. The HI features in this region suggest that DDO 120 is probably the origin of the HI stream extending from the northern end of NGC 4288 to M 106. This structure is similar to the SMC-LMC stream, but much longer, about 190 kpc. Furthermore, based on the distance measurements, we have determined the satellite galaxy members of M 106. With an absolute magnitude cutoff of M_B=-10, we obtained a sample of 11 member satellite galaxies for M 106. Using the observed HI mass with FAST, we studied the properties of satellite galaxies in M 106 and found that satellite galaxies with lower stellar masses exhibit more significant deviations from the star-forming main sequence (SFMS) in their specific star formation rates. Furthermore, the relationship between the HI mass of satellite galaxies and optical diameter generally follows the field galaxies relation. We discuss the possible mechanisms leading to the quenching in the M 106 group based on the new data from FAST

Earth and other rocky bodies in the inner Solar System are significantly depleted in carbon compared to the Sun and interstellar medium (ISM) dust. Observations indicate that over half of carbon in the ISM and comets is in refractory forms, like amorphous hydrocarbons and complex organics, which can be building blocks of rocky bodies. While amorphous hydrocarbons are destroyed by photolysis and oxidation, radial transport of solid particles can limit carbon depletion, except when complex organics, which are less refractory, are the main carbon source. We aim to identify conditions for severe carbon depletion in the inner Solar System by introducing more realistic factors: differences in stickiness between icy and silicate particles, and high-temperature regions in the disk's upper optically-thin layer, which were not considered in previous studies. We perform a 3D Monte Carlo simulation of radial drift and turbulent diffusion in a steady accretion disk, incorporating ice evaporation/re-condensation, photolysis/oxidation of hydrocarbons in the upper layer, and pyrolysis of complex organics. Our results show that the carbon fraction drops by two orders of magnitude inside the snow line under two conditions: i) silicate particles are much less sticky than icy particles, leading to a rapid decline in icy pebble flux while silicates accumulate inside the snow line, and ii) high-temperature regions in the disk's upper layer stir silicate particles into UV-exposed areas. These conditions reproduce carbon depletion patterns consistent with observations and allow for diverse carbon fractions in rocky bodies. This diversity may explain the wide variation of metals in white dwarf photospheres and suggest different surface environments for rocky planets in habitable zones.

Failed supernovae (SNe), which are likely the main channel for forming stellar-mass black holes, are predicted to accompany mass ejections much weaker than typical core-collapse SNe. We conduct a grid of one-dimensional radiation hydrodynamical simulations to explore the emission of failed SNe from red supergiant progenitors, leveraging recent understanding of the weak explosion and the dense circumstellar matter (CSM) surrounding these stars. We find from these simulations and semi-analytical modeling that diffusion in the CSM prolongs the early emission powered by shock breakout/cooling. The early emission has peak luminosities of $\sim 10^7$-$10^8~L_\odot$ in optical and UV, and durations of days to weeks. The presence of dense CSM aids detection of the early bright peak from these events via near-future wide-field surveys such as Rubin Observatory, ULTRASAT and UVEX.

The current observational tensions in the standard cosmological model have reinforced the research on dynamical dark energy, in particular on models with non-gravitational interaction between the dark components. Late-time observables like type Ia supernovas (SNe Ia) and large-scale structures (LSS) point to an energy flux from dark energy to dark matter, while the anisotropy spectrum of the cosmic microwave background (CMB) points to a small flux from dark matter to dark energy, fully consistent with no interaction at all. As background and visible matter tests are insensitive to the suppression/enhancement in the dark matter power spectrum, which is a characteristic of interacting models, while the CMB spectrum is strongly affected by it, this could be the origin of those results. In order to confirm it and at the same time to rule out the role of possible systematics between early and late-time observations, the use of a low redshift observable sensitive to the gravitational potential generated by dark matter is crucial. In the present paper, we investigate the observational viability of a class of interacting dark energy models, namely with energy exchange between vacuum-type and dust components, in the light of the Dark Energy Survey (DES) observations of galaxy weak lensing, in the context of a spatially-flat Friedmann-Lemaître-Robertson-Walker spacetime. The best fit of our analysis is compatible with null interaction, with a weak preference for an energy flux from dark matter to dark energy, confirming the CMB based constraints.

We present a generalisation of the standard pseudo-$C_\ell$ approach for power spectrum estimation to the case of spin-$s$ fields weighted by a general positive-definite weight matrix that couples the different spin components of the field (e.g. $Q$ and $U$ maps in CMB polarisation analyses, or $\gamma_1$ and $\gamma_2$ shear components in weak lensing). Relevant use cases are, for example, data with significantly anisotropic noise properties, or situations in which different masks must be applied to the different field components. The weight matrix map is separated into a spin-0 part, which corresponds to the ``mask'' in the standard pseudo-$C_\ell$ approach, and a spin-$2s$ part sourced solely by the anisotropic elements of the matrix, leading to additional coupling between angular scales and $E/B$ modes. The general expressions for the mode-coupling coefficients involving the power spectra of these anisotropic weight components are derived and validated. The generalised algorithm is as computationally efficient as the standard approach. We implement the method in the public code NaMaster.

We use the dispersion measure (DM) of localised Fast Radio Bursts (FRBs) to constrain cosmological and host galaxy parameters using simulation-based inference (SBI) for the first time. By simulating the large-scale structure of the electron density with the Generator for Large-Scale Structure (GLASS), we generate log-normal realisations of the free electron density field, accurately capturing the correlations between different FRBs. For the host galaxy contribution, we rigorously test various models, including log-normal, truncated Gaussian and Gamma distributions, while modelling the Milky Way component using pulsar data. Through these simulations, we employ the truncated sequential neural posterior estimation method to obtain the posterior. Using current observational data, we successfully recover the amplitude of the DM-redshift relation, consistent with Planck, while also fitting both the mean host contribution and its shape. Notably, we find no clear preference for a specific model of the host galaxy contribution. Although SBI may not yet be strictly necessary for FRB inference, this work lays the groundwork for the future, as the increasing volume of FRB data will demand precise modelling of both the host and large-scale structure components. Our modular simulation pipeline offers flexibility, allowing for easy integration of improved models as they become available, ensuring scalability and adaptability for upcoming analyses using FRBs. The pipeline is made publicly available under this https URL.

Motivated by the fact that a sharply peaked curvature spectrum is often considered in the literature, we examine theoretical constraints on the sharpness of such a spectrum. In particular, we show that the sharply peaked curvature power spectrum, originating from the enhancement of subhorizon perturbations during inflation, is significantly constrained by energy conservation. While the constraints do not depend on the exact form of inflaton potential, we also study concrete inflaton potentials that realize a sharply peaked curvature spectrum and how theoretical limits are saturated in these cases.

We investigate the observable characteristics of the extended atmospheres of AGB stars across a wide range of radio and (sub-)mm wavelengths using state-of-the-art 1D dynamical atmosphere and wind models over one pulsation period. We also study the relationships between the observable features and model properties. We further study practical distance ranges for observable sources assuming the capabilities of current and upcoming observatories. We present time-variable, frequency-dependent profiles of pulsating AGB stars' atmospheres, illustrating observable features in resolved and unresolved observations, including disc brightness temperature, photosphere radius, and resolved and unresolved spectral indices. Notably, temporal variations in disc brightness temperature closely mirror the temperature variability of the stellar atmosphere. We find that while the photospheric radius decreases due to gas dilution in the layers between consecutive shocks, the increase in the observed stellar radius reflects shock propagation through the atmosphere during the expansion phase, providing a direct measurement method for the shock velocity. Furthermore, our models indicate that enhanced gas temperatures after the passage of a strong shock might be observable in the high-frequency ALMA bands as a decrease in the brightness temperature with increasing frequency. We demonstrate that synthetic observations based on state-of-the-art dynamical atmosphere and wind models are necessary for proper interpretations of current (ALMA and VLA) and future (SKA and ngVLA) observations and that multi-wavelength observations of AGB stars are crucial for empirical studies of their extended atmospheres.

Accurate atmospheric parameters and chemical composition of planet-hosting stars are crucial for characterising exoplanets and understanding their formation and evolution. Our objective is to uniformly determine the atmospheric parameters and chemical abundances of carbon, nitrogen, oxygen, and the $\alpha$-elements, magnesium and silicon, along with C/O, N/O and Mg/Si abundance ratios in planet-hosts. We aim to investigate the potential links between stellar chemistry and the presence of planets using high-resolution spectra of 149 F, G, and K dwarf and giant stars hosting planets or planetary systems. The spectra were obtained with the Vilnius University Echelle Spectrograph on the 1.65 m Molėtai Observatory telescope. Stellar parameters were determined through standard analysis using equivalent widths and one-dimensional, plane-parallel model atmospheres calculated under the assumption of local thermodynamical equilibrium. The differential synthetic spectrum method was used to uniformly determine carbon C(C2), nitrogen N(CN), oxygen [O I], magnesium Mg I, and silicon Si I elemental abundances as well as the C/O, N/O, and Mg/Si ratios. We found that [C/Fe], [O/Fe], and [Mg/Fe] are lower in metal-rich dwarf hosts; whereas [N/Fe] is close to the Solar ratio. Giants show smaller scatter in [C/Fe] and [O/Fe] and lower than the Solar average [C/Fe] and C/O ratios. The (C+N+O) abundances increase with [Fe/H] in giant stars, with a minimal scatter. We also noted an overabundance of Mg and Si in planet hosting stars, particularly at lower metallicities, and a lower Mg/Si ratio in stars with planets. In giants hosting high-mass planets, nitrogen shows a moderate positive relationship with planet mass. C/O and N/O ratios show moderate negative and positive slopes in giant stars, respectively. The Mg/Si ratio shows a negative correlation with planet mass across the entire stellar sample.

Dark matter (DM) self-interactions alter the matter distribution on galactic scales and alleviate tensions with observations. A feature of the self-interaction cross section is its angular dependence, influencing offsets between galaxies and DM halos in merging galaxy clusters. While algorithms for modelling mostly forward-dominated or mostly large-angle scatterings exist, incorporating realistic angular dependencies, such as light mediator models, within $N$-body simulations remains challenging. We develop, validate and apply a novel and efficient method, combining existing approaches to describe small- and large-angle scattering regimes within a hybrid scheme. Below a critical angle the effective description via a drag force combined with transverse momentum diffusion is used, while above the angle-dependence is sampled explicitly. First, we verify the scheme using a test set-up with known analytical solutions, and check that our results are insensitive to the choice of the critical angle within an expected range. Next, we demonstrate that our scheme speeds up the computations by multiple orders of magnitude for realistic light mediator models. Finally, we apply the method to galaxy cluster mergers and discuss the sensitivity of the offset between galaxies and DM to the angle-dependence of the cross section. Our scheme ensures accurate offsets for mediator mass $m_\phi$ and DM mass $m_\chi$ within the range $0.1v/c\lesssim m_\phi/m_\chi\lesssim v/c$, while for larger (smaller) mass ratios the offsets obtained for isotropic (forward-dominated) self-scattering are approached. Here $v$ is the typical velocity scale. Equivalently, the upper condition can be expressed as $1.1\lesssim \sigma_{\rm tot}/\sigma_{\mathrm{\widetilde{T}}}\lesssim 10$ for the ratio of total and momentum transfer cross sections, with the ratio being $1$ ($\infty$) in the isotropic (forward-dominated) limits.