Papers for Tuesday, Oct 03 2023

Tidal Disruption Events (TDEs) are routinely observed in quiescent galaxies, as stars from the nuclear star cluster are scattered into the loss cone of the central supermassive black hole (SMBH). TDEs are also expected to occur in Active Galactic Nuclei (AGN), due to scattering or orbital eccentricity pumping of stars embedded in the AGN accretion disk. Encounters with embedded stellar-mass black holes (BH) can result in AGN $\mu$TDEs. AGN TDEs and $\mu$TDEs could therefore account for a fraction of observed AGN variability. Here, by performing scattering experiments with the few-body code SpaceHub, we compute the probability of AGN TDEs and $\mu$TDEs as a result of 3-body interactions between stars and binary BH. We find that AGN TDEs are more probable during the early life of the AGNs, when rates are $\sim 0.006-0.17\rm{AGN}^{-1}$~yr$^{-1}$, significantly higher than in quiescent galactic nuclei. By contrast, $\mu$TDEs should occur throughout the AGN lifetime at a rate of $\sim 7\times 10^{-7} - 2\times 10^{-5}$~yr$^{-1}$. Detection and characterization of AGN TDEs and $\mu$ AGN TDEs with future surveys using Rubin and Roman will help constrain the populations of stars \& compact objects embedded in AGN disks, a key input for the LIGO/Virgo AGN channel.

Recent observations of changing-look active galactic nuclei (AGN) hint at a frequency of accretion activity not fully explained by tidal disruption events (TDEs) stemming from relaxation processes in nucleus star clusters (NSCs), traditionally estimated to occur at rates of $10^{-4}$ to $10^{-5}$ yr$^{-1}$ per galaxy. In this letter, we propose an enhanced TDE rate through the AGN disk capture process, presenting a viable explanation for the frequent transitions observed in changing-look AGN. Specifically, we investigate the interaction between the accretion disk and retrograde stars within NSCs, resulting in the rapid occurrence of TDEs within a condensed time frame. Through detailed calculations, we derive the time-dependent TDE rates for both relaxation-induced TDE and disk-captured TDE. Our analysis reveals that TDEs triggered by the disk capture process can notably amplify the TDE rate by several orders of magnitude during the AGN phase. This mechanism offers a potential explanation for the enhanced high-energy variability characteristic of changing-look AGNs.

Stellar kinematics provide a window into the gravitational field, and therefore into the distribution of all mass, including dark matter. Deep Potential is a method for determining the gravitational potential from a snapshot of stellar positions in phase space, using mathematical tools borrowed from deep learning to model the distribution function and solve the Collisionless Boltzmann Equation. In this work, we extend the Deep Potential method to rotating systems, and then demonstrate that it can accurately recover the gravitational potential, density distribution and pattern speed of a simulated barred disc galaxy, using only a frozen snapshot of the stellar velocities. We demonstrate that we are able to recover the bar pattern speed to within 15% in our simulated galaxy using stars in a 4 kpc sub-volume centered on a Solar-like position, and to within 20% in a 2 kpc sub-volume. In addition, by subtracting the mock "observed" stellar density from the recovered total density, we are able to infer the radial profile of the dark matter density in our simulated galaxy. This extension of Deep Potential is an important step in allowing its application to the Milky Way, which has rotating features, such as a central bar and spiral arms, and may moreover provide a new method of determining the pattern speed of the Milky Way bar.

The dynamical formation channels of gravitational wave (GW) sources typically involve a stage when the compact object binary source interacts with the environment, which may excite its eccentricity, yielding efficient GW emission. For the wide eccentric compact object binaries, the GW emission happens mostly near the pericenter passage, creating a unique, burst-like signature in the waveform. This work examines the possibility of stellar-mass bursting sources in the millihertz band for future LISA detections. Because of their long lifetime ($\sim 10^{7}\rm\, yr$) and promising detectability, the number of millihertz bursting sources can be large in the local universe. For example, based on our estimates, there will be $\sim 3 - 45$ bursting binary black holes in the Milky Way, with $\sim 10^{2} - 10^{4}$ bursts detected during the LISA mission. Moreover, we find that the number of bursting sources strongly depends on their formation history. If certain regions undergo active formation of compact object binaries in the recent few million years, there will be a significantly higher bursting source fraction. Thus, the detection of millihertz GW bursts not only serves as a clue for distinguishing different formation channels, but also helps us understand the star formation history in different regions of the Milky Way.

We introduce a new method to calculate dark matter halo density profiles from simulations. Each particle is 'smeared' over its orbit to obtain a dynamical profile that is averaged over a dynamical time, in contrast to the traditional approach of binning particles based on their instantaneous positions. The dynamical and binned profiles are in good agreement, with the dynamical approach showing a significant reduction in Poisson noise in the innermost regions. We find that the inner cusps of the new dynamical profiles continue inward all the way to the softening radius, reproducing the central density profile of higher resolution simulations within the 95$\%$ confidence intervals, for haloes in virial equilibrium. Folding in dynamical information thus provides a new approach to improve the precision of dark matter density profiles at small radii, for minimal computational cost. Our technique makes two key assumptions: that the halo is in equilibrium (phase mixed), and that the potential is spherically symmetric. We discuss why the method is successful despite strong violations of spherical symmetry in the centres of haloes, and explore how substructures disturb equilibrium at large radii.

We introduce spatiotemporal-graph models that concurrently process data from the twin advanced LIGO detectors and the advanced Virgo detector. We trained these AI classifiers with 2.4 million \texttt{IMRPhenomXPHM} waveforms that describe quasi-circular, spinning, non-precessing binary black hole mergers with component masses $m_{\{1,2\}}\in[3M_\odot, 50 M_\odot]$, and individual spins $s^z_{\{1,2\}}\in[-0.9, 0.9]$; and which include the $(\ell, |m|) = \{(2, 2), (2, 1), (3, 3), (3, 2), (4, 4)\}$ modes, and mode mixing effects in the $\ell = 3, |m| = 2$ harmonics. We trained these AI classifiers within 22 hours using distributed training over 96 NVIDIA V100 GPUs in the Summit supercomputer. We then used transfer learning to create AI predictors that estimate the total mass of potential binary black holes identified by all AI classifiers in the ensemble. We used this ensemble, 3 AI classifiers and 2 predictors, to process a year-long test set in which we injected 300,000 signals. This year-long test set was processed within 5.19 minutes using 1024 NVIDIA A100 GPUs in the Polaris supercomputer (for AI inference) and 128 CPU nodes in the ThetaKNL supercomputer (for post-processing of noise triggers), housed at the Argonne Leadership Supercomputing Facility. These studies indicate that our AI ensemble provides state-of-the-art signal detection accuracy, and reports 2 misclassifications for every year of searched data. This is the first AI ensemble designed to search for and find higher order gravitational wave mode signals.

Dust-obscured star formation has dominated the cosmic history of star formation since z = 4. However, the recent finding of significant amount of dust in galaxies out to z = 8 has opened the new frontier of investigating the origin of dust also in the earliest phases of galaxy formation, within the first 1.5 billion years from the Big Bang. This is a key and rapid transition phase for the evolution of dust, as galaxy evolutionary timescales become comparable with the formation timescales of dust. It is also an area of research that is experiencing an impressive growth, especially thanks to the recent results from cutting edge observing facilities, groundbased and in space. Our aim is to provide an overview of the several findings on dust formation and evolution at z > 4, and of the theoretical efforts to explain the observational results. We have organized the review in two parts. In the first part, presented here, we focus on dust sources, primarily supernovae and asymptotic giant branch stars, and the subsequent reprocessing of dust in the interstellar medium, though grain destruction and growth. We also discuss other dust production mechanisms, such as Red Super Giants, Wolf-Rayet stars, Classical Novae, type Ia supernovae, and dust formation in quasar winds. The focus of this first part is on theoretical models of dust production sources, although we also discuss the comparison with observations. In the second part, which will be published later on, we will focus on the recent observational results at z > 4, discussing the theoretical models that have been proposed to interpret those results, as well as the profound implications for galaxy formation.

We discuss the origin of a very unusual spectral structure observed in the Fe-K band of the Seyfert galaxy Mrk 1513, a local ($z$=0.063) active galactic nucleus (AGN) that is efficiently accreting matter onto its central supermassive black hole ($L_{\rm bol}/L_{\rm Edd}\sim$0.5). We consider the highest quality X-ray observation of this source available to date, performed in 2003 by XMM-Newton. The hard X-ray spectrum is characterised by a remarkable spectral drop at $\sim$7 keV, which can be interpreted as either the onset of a broad absorption trough or the blue wing of a relativistic emission line. Overall, this complex feature is significant at >5$\sigma$, and it is qualitatively reminiscent of a P-Cygni profile. A serendipitous spectrum of lower quality taken by XMM-Newton in 2015 qualitatively confirms the presence of similar Fe-K structures. Although it is not possible to distinguish between the two physical scenarios on sheer statistical grounds with the current data, several considerations lend weight to the possibility that Mrk 1513 is actually hosting a persistent outflow at accretion-disc scales, thus adding to the handful of known AGN in which a wide-angle X-ray wind has been identified so far.

We attempt to detect signal of Yarkovsky-related acceleration in the orbits of 134 main belt asteroids (MBAs) we observed with the University of Hawai'i 88-inch telescope, supplemented with observations publicly available from the Minor Planet Center and Gaia Data Release 3. We estimated expected Yarkovsky acceleration values based on parameters derived through thermophysical modeling, but we were not able to find any reliable detections of Yarkovsky in our sample. Through tests with synthetic observations however, we estimated the minimum observational arc length needed to detect the Yarkovsky effect for all of our sample MBAs, which in nearly every case exceeded the current arc length of the existing observations. We find that the Yarkovsky effect could be detectable within a couple of decades of discovery for a 100-m MBA assuming 0.1" astrometric accuracy, which is at the size range detectable by the upcoming Vera Rubin Observatory Legacy Survey of Space and Time.

We revisit kinetic relaxation and soliton/Boson star nucleation in fuzzy scalar dark matter featuring short-ranged self-interactions $\mathcal{H}_{\rm int} = -\lambda|\psi|^4/2m^2$, alongside gravitational self-interactions. We map out the full curve of nucleation timescale for both repulsive ($\lambda < 0$) and attractive ($\lambda > 0$) short-ranged self-interaction strength, and in doing so reveal two new points. Firstly, besides the two usual terms, $\propto G^2$ and $\propto \lambda^2$, in the total relaxation rate $\Gamma_{\rm relax}$, there is an additional cross term $\propto G\lambda$ arising due to interference between gravitational and short-ranged self-interaction scattering amplitudes. This yields a critical repulsive interaction strength $\lambda_{\rm cr} \simeq - 2\pi Gm^2/v_{0}^2$, at which the relaxation rate is smallest and serves as the transition point between typical net attractive self-interaction ($\lambda \gtrsim \lambda_{\rm cr}$), and net repulsive self-interaction ($-\lambda \gtrsim -\lambda_{\rm cr}$). Secondly, while in the net attractive regime, nucleation time scale is similar to inverse relaxation time scale $\tau_{\rm nuc} \sim \Gamma^{-1}_{\rm relax}$, in the net repulsive regime nucleation occurs at a delayed time $\tau_{\rm nuc} \sim (\lambda/\lambda_{\rm cr})\Gamma^{-1}_{\rm relax}$. We confirm our analytical understanding by performing 3D field simulations with varying average mass density $\bar{\rho}$, box size $L$ and grid size $N$.

We search for signatures of cosmological shocks in gas pressure profiles of galaxy clusters using the cluster catalogs from three surveys: the Dark Energy Survey (DES) Year 3, the South Pole Telescope (SPT) SZ survey, and the Atacama Cosmology Telescope (ACT) data releases 4, 5, and 6, and using thermal Sunyaev-Zeldovich (SZ) maps from SPT and ACT. The combined cluster sample contains around $10^5$ clusters with mass and redshift ranges $10^{13.7} < M_{\rm 200m}/M_\odot < 10^{15.5}$ and $0.1 < z < 2$, and the total sky coverage of the maps is $\approx 15,000 \,\,{\rm deg}^2$. We find a clear pressure deficit at $R/R_{\rm 200m}\approx 1.1$ in SZ profiles around both ACT and SPT clusters, estimated at $6\sigma$ significance, which is qualitatively consistent with a shock-induced thermal non-equilibrium between electrons and ions. The feature is not as clearly determined in profiles around DES clusters. We verify that measurements using SPT or ACT maps are consistent across all scales, including in the deficit feature. The SZ profiles of optically selected and SZ-selected clusters are also consistent for higher mass clusters. Those of less massive, optically selected clusters are suppressed on small scales by factors of 2-5 compared to predictions, and we discuss possible interpretations of this behavior. An oriented stacking of clusters -- where the orientation is inferred from the SZ image, the brightest cluster galaxy, or the surrounding large-scale structure measured using galaxy catalogs -- shows the normalization of the one-halo and two-halo terms vary with orientation. Finally, the location of the pressure deficit feature is statistically consistent with existing estimates of the splashback radius.

The discovery and timing follow-up of millisecond pulsars (MSPs) are necessary not just for their usefulness in Pulsar Timing Arrays (PTAs) but also for investigating their own intriguing properties. In this work, we provide the findings of the decade-long timing of the four MSPs discovered by Giant Metre-wave Radio Telescope (GMRT), including their timing precision, model parameters, and newly detected proper motions. We compare the timing results for these MSPs before and after the GMRT upgrade in 2017, characterising the improvement in timing precision due to the bandwidth upgrade. We discuss the suitability of these four GMRT MSPs for the PTA experiments as well as the usefulness of their decade-long timing data in the global effort to improve the signal-to-noise (S/N) of recently detected signature of gravitational waves in cross-correlation statistics of residuals of MSPs.

As astronomical data grows in volume and complexity, the scalability of analysis software becomes increasingly important. At the same time, astrophysics analysis software relies heavily on open-source contributions, so languages and tools that prioritize both performance and readability are especially valuable. Julia, with its just-in-time compiler and high level syntax, offers a compelling alternative to traditional languages like Python or C. In this paper, we outline ShOpt.jl, a new software package for point spread function (PSF) characterization written in Julia. ShOpt.jl features a number of performance optimizations, such as multithreading, the use of preconditioners, and the implementation of the memory-limited Broyden-Fletcher-Goldfarb-Shanno algorithm, as well as the flexibility to choose between principal component analysis, an autoencoder, and analytic profiles for PSF characterization. As observatories like the James Webb Space Telescope bring astrophysics into a new era of wide-field, high-resolution imaging, the challenges of PSF modeling become more pronounced. Tools like ShOpt.jl provide the community with a scalable, efficient, and accurate solution to these challenges, while also demonstrating the potential of Julia as a language that meets the demands of modern astrophysical research.

Accretion rates ($\dot{M}$) of young stars show a strong correlation with object mass ($M$); however, extension of the $\dot{M}-M$ relation into the substellar regime is less certain. Here, we present the Comprehensive Archive of Substellar and Planetary Accretion Rates (CASPAR), the largest to-date compilation of substellar accretion diagnostics. CASPAR includes: 658 stars, 130 brown dwarfs, and 10 bound planetary mass companions. In this work, we investigate the contribution of methodological systematics to scatter in the $\dot{M}-M$ relation, and compare brown dwarfs to stars. In our analysis, we rederive all quantities using self-consistent models, distances, and empirical line flux to accretion luminosity scaling relations to reduce methodological systematics. This treatment decreases the original $1\sigma$ scatter in the $\log \dot{M}-\log M$ relation by $\sim17$%, suggesting that it makes only a small contribution to the dispersion. CASPAR rederived values are best fit by $\dot{M}\propto M^{2.02\pm0.06}$ from 10~$M_\mathrm{J}$ to 2~$M_\odot$, confirming previous results. However, we argue that the brown dwarf and stellar populations are better described separately and by accounting for both mass and age. Therefore, we derive separate age-dependent $\dot{M}-M$ relations for these regions, and find a steepening in the brown dwarf $\dot{M}-M$ slope with age. Within this mass regime, the scatter decreases from 1.36 dex to 0.94 dex, a change of $\sim$44%. This result highlights the significant role that evolution plays in the overall spread of accretion rates, and suggests that brown dwarfs evolve faster than stars, potentially as a result of different accretion mechanisms.

The origin of Uranus and Neptune has long been challenging to explain, due to the large orbital distances from the Sun. After a planetary embryo has been formed, the main accretion processes are likely pebble, gas and planetesimal accretion. Previous studies of Uranus and Neptune formation typically don't consider all three processes; and furthermore, do not investigate how the formation of the outer planet impacts the inner planet. In this paper we study the concurrent formation of Uranus and Neptune via both pebble, gas and planetesimal accretion. We use a dust-evolution model to predict the size and mass flux of pebbles, and derive our own fit for gas accretion. We do not include migration, but consider a wide range of formation locations between 12 and 40au. If the planetary embryos form at the same time and with the same mass, our formation model with an evolving dust population is unable to produce Uranus and Neptune analogues. This is because the mass difference between the planets and the H-He mass fractions become too high. However, if the outer planetary embryo forms earlier and/or more massive than the inner embryo, the two planets do form in a few instances when the disk is metal-rich and dissipates after a few Myr. Furthermore, our study suggests that in-situ formation is rather unlikely. Nethertheless, giant impacts and/or migration could potentially aid in the formation, and future studies including these processes could bring us one step closer to understanding how Uranus and Neptune formed.

As the number of planetary mass objects (PMOs, $\lessapprox$13 M$_{\rm{Jupitr}}$) at wider separation ($\gtrapprox$10 AU) grows, there is emerging evidence that they form differently from their higher-mass brown-dwarf (BD) counterparts. Namely, PMOs' atmospheres are enriched by metals which is usually interpreted as a sign of solid accretion. This points to the formation channel through core accretion. However, there has hitherto been no quantitative analysis at population level to investigate the amount and timing of solid accretion. Here, we analyze a sample of five directly-imaged exoplanets with measured stellar and planetary chemical abundances (51 Eri b, $\beta$ Pic b, HIP 65426 b, and HR 8799 c and e). We show that these PMOs accrete large amount of solids regardless of formation channels. On average $\gtrapprox$100 M$_\oplus$ solids (ranging from 98.6 to 845.2 M$_\oplus$ for individual systems) are accreted to enrich planet atmospheres if forming via core accretion whereas the solid accretion needs to be $\gtrapprox$20 M$_\oplus$ (ranging from 22.4 to 782.3 M$_\oplus$) if forming via gravitational instability. The result implies that the solid accretion process has to happen at an early stage ($<$1 Myr) when large amount of solids are available in young protoplanetary disks.

Half of the JWST high-contrast imaging objects will only have photometric data {{as of Cycle 2}}. However, to better understand their atmospheric chemistry which informs formation origin, spectroscopic data are preferred. Using HIP 65426 b, we investigate to what extent planet properties and atmospheric chemical abundance can be retrieved with only JWST photometric data points (2.5-15.5 $\mu$m) in conjunction with ground-based archival low-resolution spectral data (1.0-2.3 $\mu$m). We find that the data is consistent with an atmosphere with solar metallicity and C/O ratios at 0.40 and 0.55. We rule out 10x solar metallicity and an atmosphere with C/O = 1.0. We also find strong evidence of silicate clouds but no sign of an enshrouding featureless {{dust}} extinction. This work offers guidance and cautionary tales on analyzing data in the absence of medium-to-high resolution spectral data.

Galactic winds play essential roles in the evolution of galaxies through the feedback they provide. Despite intensive studies of winds, the radial distributions of their properties and feedback are rarely observable. Here we present such measurements for the prototypical starburst galaxy, M 82, based on observations by Subaru telescope. We determine the radial distribution of outflow densities ($n_e$) from the spatially-resolved [S II] $\lambda\lambda$ 6717, 6731 emission-lines. We find $n_e$ drops from 200 to 40 cm$^{-3}$ with radius ($r$) between 0.5 and 2.2 kpc with a best-fit power-law index of $r^{-1.2}$. Combined with resolved H$\alpha$ lines, we derive mass, momentum, and energy outflow rates, which drop quite slowly (almost unchanged within error bars) over this range of $r$. This suggests that the galactic wind in M 82 can carry mass, momentum, and energy from the central regions to a few kpc with minimal losses. We further derive outflow cloud properties, including size and column densities. The clouds we measure have pressures and densities that are too high to match those from recent theoretical models and numerical simulations of winds. By comparing with a sample of outflows in local star-forming galaxies studied with UV absorption-lines, the above-derived properties for M 82 outflows match well with the published scaling relationships. These matches suggest that the ionized gas clouds traced in emission and absorption are strongly related. Our measurements motivate future spatially resolved studies of galactic winds, which is the only way to map the structure of their feedback effects.

This work tests if the large-scale galaxy distribution can be characterized as a fractal system. The $\Lambda$CDM cosmology with $H_0=(70\pm 5)$ km/s/Mpc is adopted to study the UltraVISTA DR1, COSMOS2015 and SPLASH surveys, alongside the number density equations of these galaxy distribution systems as fractals with dimension D. The relativistic distance definitions $d_L$, $d_Z$ and $d_G$ are used to estimate the galaxy number densities in the redshift interval $0.1 \leq z \leq 4$ at volume limited subsamples. Applying the appropriate relations for the description of galaxy fractal structures with single dimension $D$ in the relativistic settings to these surveys datasets it is possible to state that for $z<1$ the UltraVISTA DR1 galaxies presented an average of $D=(1.58\pm 0.20)$, the COSMOS2015 galaxies produced $D=(1.39\pm 0.19)$ and the SPLASH galaxies generated $D=(1.00\pm 0.12)$. For $1 \leq z \leq 4$ the dimensions respectively decreased to $D=(0.59\pm 0.28)$, $D=0.54^{+0.27}_{-0.26}$ and $D=0.83^{+0.36}_{-0.37}$. These results are robust under the Hubble constant uncertainty assumed here. Analysis of blue and red galaxies subsamples in the COSMOS2015 and SPLASH surveys show that the fractal dimensions of blue galaxies present essentially no alteration from the values above, although the ones for the red galaxies changed mostly to smaller values, meaning that D may be assumed as a more intrinsic property of the distribution of objects in the Universe, thus allowing for the fractal dimension to be used as a tool to study different populations of galaxies. All results confirm the decades old theoretical prediction of a decrease in the fractal dimension for $z>1$ suggesting that either there are yet unclear observational biases causing such decrease in the fractal dimension, or the galaxy clustering was possibly more sparse and the universe void dominated in a not too distant past.

The existence of a vast nova shell surrounding the prototypical dwarf nova Z Camelopardalis (Z Cam) proves that some old novae undergo metamorphosis to appear as dwarf novae thousands of years after a nova eruption. The expansion rates of ancient nova shells offer a way to constrain both the time between nova eruptions and the time for post-nova mass transfer rates to decrease significantly, simultaneously testing nova thermonuclear runaway models and hibernation theory. Previous limits on the expansion rate of part of the Z Cam shell constrain the inter-eruption time between Z Cam nova events to be $>$ 1300 years. Deeper narrow-band imaging of the ejecta of Z Cam with the Condor Array Telescope now reveals very low surface brightness areas of the remainder of the shell. A second, even fainter shell is also detected, concentric with and nearly three times the size of the "inner" shell. This is the first observational support of the prediction that concentric shells must surround the frequently-erupting novae of relatively massive white dwarfs. The Condor images extend our Z Cam imaging baseline to 15 years, yielding the inner shell's expansion rate as $v = 83 \pm 37$ km s$^{-1}$ at 23 degrees South of West, in excellent agreement with our 2012 prediction. This velocity corresponds to an approximate age of $t = 2672^{-817}_{+2102}$ yr. While consistent with the suggestion that the most recent nova eruption of Z Cam was the transient recorded by Chinese Imperial astrologers in the year 77 BCE, the age uncertainty is still too large to support or disprove a connection with Z Cam.

Giant exoplanets have been directly imaged over orders of magnitude of orbital separations, prompting theoretical and observational investigations of their formation pathways. In this paper, we present new VLTI/GRAVITY astrometric data of HIP 65426 b, a cold, giant exoplanet which is a particular challenge for most formation theories at a projected separation of 92 au from its primary. Leveraging GRAVITY's astrometric precision, we present an updated eccentricity posterior that disfavors large eccentricities. The eccentricity posterior is still prior-dependent, and we extensively interpret and discuss the limits of the posterior constraints presented here. We also perform updated spectral comparisons with self-consistent forward-modeled spectra, finding a best fit ExoREM model with solar metallicity and C/O=0.6. An important caveat is that it is difficult to estimate robust errors on these values, which are subject to interpolation errors as well as potentially missing model physics. Taken together, the orbital and atmospheric constraints paint a preliminary picture of formation inconsistent with scattering after disk dispersal. Further work is needed to validate this interpretation. Analysis code used to perform this work is available at https://github.com/sblunt/hip65426.

V1298 Tau is a young pre-main sequence star hosting four known exoplanets that are prime targets for transmission spectroscopy with current-generation instruments. This work pieces together observations from the NICER X-ray telescope, the Space Telescope Imaging Spectrograph and Cosmic Origins Spectrograph instruments aboard Hubble Space Telescope, and empirically informed models to create a panchromatic spectral energy distribution for V1298 Tau spanning 1 to 100000 Angstroms. We describe the methods and assumptions used to assemble the panchromatic spectrum and show that despite this star's brightness, its high-energy spectrum is near the limit of present X-ray and ultraviolet observatories' abilities to characterize. We conclude by using the V1298 Tau spectrum as a benchmark for the activity saturation stage of high-energy radiation from solar-mass stars to compare the lifetime cumulative high-energy irradiation of the V1298 Tau planets to other planets orbiting similarly massive stars.

We present high-cadence photometric and spectroscopic observations of SN~2023axu, a classical Type II supernova with an absolute $V$-band peak magnitude of $-16.5 \pm 0.1$ mag. SN~2023axu was discovered by the Distance Less Than 40 Mpc (DLT40) survey within 1 day of the last non-detection in the nearby galaxy NGC 2283 at 13.7 Mpc. We modeled the early light curve using a recently updated shock cooling model that includes the effects of line blanketing and found the explosion epoch to be MJD 59971.48 $\pm$ 0.03 and the probable progenitor to be a red supergiant with a radius of 417 $\pm$ 28 $R_\odot$. The shock cooling model cannot match the rise of observed data in the $r$ and $i$ bands and underpredicts the overall UV data which points to possible interaction with circumstellar material. This interpretation is further supported by spectral behavior. We see a ledge feature around 4600 \AA\ in the very early spectra (+1.1 and +1.5 days after the explosion) which can be a sign of circumstellar interaction. The signs of circumstellar material are further bolstered by the presence of absorption features blueward of H$\alpha$ and H$\beta$ at day $>$40 which is also generally attributed to circumstellar interaction. Our analysis shows the need for high-cadence early photometric and spectroscopic data to decipher the mass-loss history of the progenitor.

We propose an efficient and robust method to estimate the halo concentration based on the first moment of the density distribution, which is $R_1\equiv \int_0^{r_{\rm vir}}4\pi r^3\rho(r)dr/M_{\rm vir}/r_{\rm vir}$. We find that $R_1$ has a monotonic relation with the concentration parameter of the NFW profile, and that a cubic polynomial function can fit the relation with an error $\lesssim 3\%$. Tests on ideal NFW halos show that the conventional NFW profile fitting method and the $V_{\rm max}/V_{\rm vir}$ method produce biased halo concentration estimation by $\approx 10\%$ and $\approx 30\%$, respectively, for halos with 100 particles. In contrast, the systematic error for our $R_1$ method is smaller than $0.5\%$ even for halos containing only 100 particles. Convergence tests on realistic halos in $N$-body simulations show that the NFW profile fitting method underestimates the concentration parameter for halos with $\lesssim 300$ particles by $\gtrsim 20\%$, while the error for the $R_1$ method is $\lesssim 8\%$. We also show other applications of $R_1$, including estimating $V_{\rm max}$ and the Einasto concentration $c_{\rm e}\equiv r_{\rm vir}/r_{-2}$. The calculation of $R_1$ is efficient and robust, and we recommend including it as one of the halo properties in halo catalogs of cosmological simulations.

Supermassive black holes (SMBHs) with masses of $\sim 10^9 {\rm M_\odot}$ within the first billion year of the universe challenge our conventional understanding of black hole formation and growth. One pathway to these SMBHs proposes that supermassive stars (SMSs) born in pristine atomic cooling haloes (ACHs) yield massive seed BHs evolving to these early SMBHs. This scenario leads to an overly massive BH galaxy (OMBG), in which the BH to stellar mass ratio is initially $M_{\rm bh}/M_* \geq 1$, well in excess of the typical values of $\sim 10^{-3}$ at low redshifts. Previously, we have investigated two massive seed BH candidates from the \texttt{Renaissance} simulation and found that they remain outliers on the $M_{\rm bh}-M_{*}$ relation until the OMBG merges with a much more massive halo at $z{=}8$. In this work, we use Monte-Carlo merger trees to investigate the evolution of the $M_{\rm bh}-M_{*}$ relation for $50,000$ protogalaxies hosting massive BH seeds, across $10,000$ trees that merge into a $10^{12} {\rm M_\odot}$ halo at $z{=}6$. We find that up to $60\%$ (depending on growth parameters) of these OMBGs remain strong outliers for several 100 Myr, down to redshifts detectable with {\it JWST} and with sensitive X-ray telescopes. This represents a way to diagnose the massive-seed formation pathway for early SMBHs. We expect to find ${\sim} 0.1{-}1$ of these objects per {\it JWST} NIRCam field per unit redshift at $z\gtrsim 6$. Recently detected SMBHs with masses of $\sim 10^7~{\rm M_\odot}$ and low inferred stellar-mass hosts may be examples of this population.

The black hole (BH) mass and luminosity are key factors in determining how a quasar interacts with its environment. In this study, we utilise data from the European Southern Observatory Large Programme XQ-100, a high-quality sample of 100 X-shooter spectra of the most luminous quasars in the redshift range $3.5 < z < 4.5$, and measure the properties of three prominent optical and ultraviolet broad emission-lines present in the wide wavelength coverage of X-shooter: CIV, MgII, and H$\beta$. The line properties of all three broad lines are used for virial estimates of the BH mass and their resulting mass estimates for this sample are tightly correlated. The BH mass range is $\log{(\rm{M_{BH}}/\rm{M_\odot})} = 8.6-10.3$ with bolometric luminosities estimated from the 3000A continuum in the range $\log{(\rm{L_{bol}}/\rm{erg\,s^{-1}})} = 46.7-48.0$. Robustly determined properties of these quasars enable a variety of follow-up research in quasar astrophysics, from chemical abundance and evolution in the broad-line region to radiatively driven quasar outflows.

The solar ultraviolet intensities of spectral lines originating from Li- and Na-like ions have been observed to surpass the expectations derived from plasmas with coronal approximation. The violation of the coronal approximation can be partially attributed to non-equilibrium ionization (NEI) due to dynamic processes occurring in the vicinity of the transition region. However, the quantitative analysis of these dynamic effects has not yet been conducted. To investigate the impact of these dynamics, a set of equations governing NEI for multiple ion species was solved numerically in conjunction with 1.5-dimensional magnetohydrodynamic equations describing an Alfven-wave-heated coronal loop. Following the injection of Alfven waves from the photosphere, the system undergoes a time evolution characterized by phases of evaporation, condensation, and quasi-steady states. During the evaporation phase, the ionization fractions of Li- and Na-like ions were observed to increase, with a maximum enhancement of 1.6 when compared to the fractions in ionization equilibrium. This over-fractionation of Li- and Na-like ions was found to be induced by the evaporation process, while collisions between shocks and the transition region did not exhibit deviations from ionization equilibrium. Consequently, the intensities calculated using the coronal approximation underestimated the intensities of Li- and Na-like ions by up to 60%. Conversely, under-fractions of at least 0.9 was observed during the condensation phase and the quasi-steady state. Given that the degree of over/under-fraction exhibits a dependency on mass motions, our study has a possibility to impose limitations on both the mass circulation in coronal heating and mass loss processes.

We present a sample of 99 dwarf galaxies ($M_*<10^{9.5} M_\odot$) with X-ray activity in their central regions. The sample was obtained from a match of the SRG/eROSITA X-ray point source catalogue in the Eastern Galactic hemisphere with the MPA-JHU SDSS catalogue. The obtained matches were cleaned rigorously with the help of external optical catalogues to increase the purity of the sample. This work is the largest study of this kind -- X-ray activity in $\approx 85$ per cent of matched dwarfs was not reported before. From their position on the BPT diagram, the majority of X-ray active dwarfs are identified as star-forming galaxies. However, for 82 objects their X-ray luminosity cannot be explained by collective emission of X-ray binaries, rendering them strong candidates for dwarf galaxies with an active accreting black hole in their centre. We find that the fraction of AGN among dwarf galaxies drops from $\sim 2\cdot 10^{-2}$ at $L_X\sim 10^{39}$ erg/s to $\sim (2-4)\cdot 10^{-4}$ at $L_X\sim 10^{41}$ erg/s and increases with the stellar mass of the host galaxy. We serendipitously discovered sources with unexpected properties. We report on a tidal disruption event (TDE) candidate in a dwarf galaxy, a massive black hole in a dwarf galaxy with a soft thermal spectrum, a luminous dwarf galaxy with an obscured X-ray spectrum and a few other peculiar sources. Among the eROSITA/MPA-JHU matches rejected in the cleaning procedure, we found three Ultra-luminous X-ray source (ULX) candidates and a sample of X-ray bright galaxy pairs, in four of which both members shine in X-rays.

The HADAR experiment, which will be constructed in Tibet, China, combines the wide-angle advantages of traditional EAS array detectors with the high sensitivity advantages of focused Cherenkov detectors. Its physics objective is to observe transient sources such as gamma-ray bursts and counterparts of gravitational waves. The aim of this study is to utilize the latest AI technology to enhance the sensitivity of the HADAR experiment. We have built training datasets and models with distinctive creativity by incorporating relevant physical theories for various applications. They are able to determine the kind, energy, and direction of incident particles after careful design. We have obtained a background identification accuracy of 98.6\%, a relative energy reconstruction error of 10.0\%, and an angular resolution of 0.22-degrees in a test dataset at 10 TeV. These findings demonstrate the enormous potential for enhancing the precision and dependability of detector data analysis in astrophysical research. Thanks to deep learning techniques, the HADAR experiment's observational sensitivity to the Crab Nebula has surpassed that of MAGIC and H.E.S.S. at energies below 0.5 TeV and remains competitive with conventional narrow-field Cherenkov telescopes at higher energies. Additionally, our experiment offers a fresh approach to dealing with strongly connected scattered data.

The contemporary multi-wavelength observations have revealed various important features during solar flares which, on one hand, support the two-dimensional (2D) "standard flare model" while, on other hand, also urge for the exploration of three-dimensional (3D) magnetic field topologies involved in flares. Traditionally, the formation of parallel ribbons on both side of the polarity inversion line (PIL) and associated overlying loop arcades have been recognized as the most prominent features of eruptive flares which has formed the basis for the development of the standard model providing a 2D description of the flare-associated phenomena. The actual flare, however, occurs in a more complicated 3D magnetic structure. Thus, despite the general applicability, the standard model has limited or no scope in explaining some of the features which exclusively requires a 3D description. In this context, the observations of "circular ribbon flares" stand out where one of the ribbons presents an almost fully closed quasi-circular or quasi-ellipsoidal shape, evidencing the involvement of a typical fan-spine magnetic configuration. In this article, we discuss observational features vis \`a vis theoretical understanding of solar flares in view of 2D and 3D models of magnetic reconnection. We highlight a few complex cases of circular ribbon flares exhibiting parallel ribbons, a coronal jet, and/or an erupting magnetic flux rope. Exploring various 3D topologies also enables us to probe similarities between the circumstances that govern the onset of jets, confined flares and CME-producing eruptive flares.

With the exponential growth in data volume, especially in recent decades, the demand for data processing has surged across all scientific fields. Within astronomical datasets, the combination of solar space missions and ground-based telescopes has yielded high spatial and temporal resolutions for observing the Sun, thus fueling an increase in the utilization of automatic image processing approaches. Image processing methodologies play a pivotal role in analyzing solar data, a critical component in comprehending the Sun's behavior and its influence on Earth. This paper provides an overview of the utilization of diverse processing techniques applied to images captured from the solar photosphere. The introduction of our manuscript furnishes a description of the solar photosphere along with its primary characteristics. Subsequently, we endeavor to outline the significance of preprocessing photospheric images, a crucial prerequisite before engaging in any form of analysis. The subsequent section delves into an examination of numerous reputable sources that have employed image processing methodologies in their research pertaining to the Sun's surface. This section also encompasses discussions concerning recent advancements in image processing techniques for solar data analysis and their potential implications for future solar research. The final section deliberates on post-processing procedures as supplementary steps that are essential for deriving meaningful results from raw data. Effectively, this paper imparts vital information, offering concise explanations regarding the Sun's surface, the application of image processing techniques to various types of photospheric images, indispensable image preprocessing stages, and post-processing procedures aimed at transforming raw data into coherent and comprehensive insights.

We present and publicly release a new star-forming regions emission library TODDLERS (Time evolution of Observables including Dust Diagnostics and Line Emission from Regions containing young Stars) for the publicly available radiative transfer code SKIRT. The library generation involves the spherical evolution of a homogeneous gas cloud around a young stellar cluster that accounts for stellar feedback processes including stellar winds, supernovae, and radiation pressure, as well as the gravitational forces on the gas. The semi-analytical evolution model is coupled with the photoionization code Cloudy to calculate time-dependent UV-mm spectral energy distributions (SEDs) from star-forming regions of varying metallicity, star-formation efficiency, birth-cloud density, and mass. The calculated SEDs include the stellar, nebular, and dust continuum emission along with a wide range of emission lines originating from H ii, photo-dissociation, and molecular gas regimes tabulated at high resolution. The SEDs incorporated in SKIRT are generated by calculating a stellar-mass normalized luminosity, which assumes that each emission source is composed of a power-law population of star-forming clouds. When compared to the previous treatment of star-forming regions in SKIRT, TODDLERS shows a better agreement with low-redshift observational data in the IR wavelength range while offering a more comprehensive line-emission support. This paves the way for a variety of applications using simulated galaxies at low and high redshift.

Recently, multiple pulsar timing array collaborations have presented compelling evidence for a stochastic signal at nanohertz frequencies, potentially originating from cosmic strings. Cosmic strings are linear topological defects that can arise during phase transitions in the early Universe or as fundamental strings in superstring theory. This paper focuses on investigating the detection capabilities of Taiji, a planned space-based gravitational wave detector, for the gravitational wave background generated by cosmic strings. By analyzing simulated Taiji data and utilizing comprehensive Bayesian parameter estimation techniques, we demonstrate a significant improvement in precision compared to the NANOGrav 15-year data, surpassing it by an order of magnitude. This highlights the enhanced measurement capabilities of Taiji. Consequently, Taiji can serve as a valuable complementary tool to pulsar timing arrays in validating and exploring the physics of cosmic strings in the early Universe.

We measure velocity offsets in the NaI $\lambda\lambda5890, 5896$ (Na D) interstellar medium absorption lines to track how neutral galactic winds change as their host galaxies evolve. Our sample of $\sim$80,000 SDSS spectra at $0.010 < z < 0.325$ includes starburst, post-starburst, and quiescent galaxies, forming an evolutionary sequence of declining star formation rate (SFR). We detect bulk flows across this sequence, mostly at higher host stellar masses($log(M_{\star}/M_{\odot})>10$). Along this sequence, the fraction of outflows decreases ($76\pm2\%$ to $65\pm4\%$ to a 3$\sigma$ upper limit of $34\%$), and the mean velocity offset changes from outflowing to inflowing ($-84.6\pm5.9$ to $-71.6\pm11.4$ to $76.6\pm2.3\,km\,s^{-1}$). Even within the post-starburst sample, wind speed decreases with time elapsed since the starburst ended. These results reveal that outflows diminish as galaxies age. For post-starbursts, there is evidence for an AGN contribution, especially to the speediest outflows: 1) SFR declines faster in time than outflow velocity, a decoupling arguing against massive stellar feedback; 2) of the few outflows strong enough to escape the interstellar medium (9/105), three of the four hosts with measured emission lines are Seyfert galaxies. For disky starburst galaxies, however, the trends suggest flows out of the stellar disk plane (with outflow 1/2-opening angle $> 45$ degree) instead of from the nucleus: the wind velocity decreases as the disk becomes more edge-on, and the outflow fraction, constant at $\sim$90$\%$ for disk inclinations $i<45$ degree, steadily decreases from $\sim$90$%$ to 20$\%$ for $i>45$ degree.

The discovery of the first binary neutron star merger, GW170817, has spawned a plethora of global numerical relativity simulations. These simulations are often ideal (with dissipation determined by the grid) and/or axisymmetric (invoking ad hoc mean-field dynamos). However, binary neutron star mergers (similar to X-ray binaries and active galactic nuclei inner discs) are characterised by large magnetic Prandtl numbers, $\rm Pm$, (the ratio of viscosity to resistivity). $\rm Pm$ is a key parameter determining dynamo action and dissipation but it is ill-defined (and likely of order unity) in ideal simulations. To bridge this gap, we investigate the magnetorotational instability (MRI) and associated dynamo at large magnetic Prandtl numbers using fully compressible, three-dimensional, vertically stratified, isothermal simulations of a local patch of a disc. We find that, within the bulk of the disc ($z\lesssim2H$, where $H$ is the scale-height), the turbulent intensity (parameterized by the stress-to-thermal-pressure ratio $\alpha$), and the saturated magnetic field energy density, $E_\text{mag}$, produced by the MRI dynamo, both scale as a power with Pm at moderate Pm ($4\lesssim \text{Pm} \lesssim 32$): $E_\text{mag} \sim \text{Pm}^{0.74}$ and $\alpha \sim \text{Pm}^{0.71}$, respectively. At larger Pm ($\gtrsim 32$) we find deviations from power-law scaling and the onset of a plateau. Compared to our recent unstratified study, this scaling with Pm becomes weaker further away from the disc mid-plane, where the Parker instability dominates. We perform a thorough spectral analysis to understand the underlying dynamics of small-scale MRI-driven turbulence in the mid-plane and of large-scale Parker-unstable structures in the atmosphere.

Disc warping, and possibly disc breaking, has been observed in protoplanetary discs around both single and multiple stars. Large disc warps can break the disc, producing observational signatures in kinematics and shadowing along the outer disc. In this work, we use comparisons of disc timescales to derive updated formulae for disc breaking, with better predictions as to when and where a disc is expected to break and how many breaks could occur. Disc breaking is more likely for discs with small inner cavities, cooler temperatures, and steeper power-law profiles. Thus, thin, polar-aligned discs are more likely to break. We test our analytic formulae using 3D grid-based simulations of protoplanetary discs warped by the gravitational torque of an inner binary. We reproduce the expected warp behaviors in different viscosity regimes and observe disc breaking at locations in agreement with our derived equations. As disc breaking is observed only for discs with low viscosity, we also consider a viscous criterion for disc breaking, where rapid alignment to the precession vector can prevent a break by reducing the maximum misalignment between neighboring rings. We apply these results to the GW Orionis circumtriple disc, and find that the precession induced from the central stars can break the disc if the disc is relatively thin. We expect repeated or multiple disc breaking to occur for discs with sufficiently steep power law profiles. We simulate a disc with steep power-law profiles, and observe two separate breaking events at locations in rough agreement with our analytical predictions.

What was the nature of the Late Hesperian climate? Warm and wet or cold and dry? Formulated this way the question leads to an apparent paradox since both options seem implausible. A warm and wet climate would have produced extensive fluvial erosion but few valley networks have been observed at the age of the late Hesperian. A too cold climate would have kept any northern ocean frozen most of the time. A moderate cold climate would have transferred the water from the ocean to the land in the form of snow and ice. But this would prevent tsunami formation, for which there is some evidence. Here, we provide new insights from numerical climate simulations in agreement with surface geological features to demonstrate that the Martian climate could have been both cold and wet. Using an advanced General Circulation Model (GCM), we demonstrate that an ocean can be stable, even if the Martian mean surface temperature is lower than 0$^\circ$C. Rainfall is moderate near the shorelines and in the ocean. The southern plateau is mostly covered by ice with a mean temperature below 0$^\circ$C and a glacier return flow back to the ocean. This climate is achieved with a 1 bar CO$_2$ dominated atmosphere with 10\% H$_2$. Under this scenario 3 Ga, the geologic evidence of a shoreline and tsunami deposits along the ocean/land dichotomy are compatible with ice sheets and glacial valleys in the southern highlands.

We apply the barred Schwarzschild method developed by Tahmasebzadeh et al. (2022) to a barred S0 galaxy, NGC 4371, observed by IFU instruments from the TIMER and ATLAS3D projects. We construct the gravitational potential by combining a fixed black hole mass, a spherical dark matter halo, and stellar mass distribution deprojected from $3.6$ $\mu$m S$^4$G image considering an axisymmetric disk and a triaxial bar. We create two sets of independent models, fitting the kinematic data derived from TIMER and ATLAS3D, separately. The models fit all the kinematic data remarkably well. We find a consistent bar pattern speed from the two sets of models, with $\Omega_{\rm p} = 23.6 \pm 2.8 \hspace{.08cm} \mathrm{km \hspace{.04cm} s^{-1} \hspace{.04cm} kpc^{-1} }$. The dimensionless bar rotation parameter is determined to be $ R_{\rm cor}/R_{\rm bar}=2.2 \pm 0.4$, indicating a slow bar in NGC 4371. Besides, we obtain a dark matter fraction $M_{\rm DM}/ M_{\rm total}$ of $\sim 0.51 \pm 0.06$ within the bar region. Our results support the scenario that bars may slow down in the presence of dynamical friction with a significant amount of dark matter in the disk regions. Based on our model, we further decompose the galaxy into multiple 3D orbital structures, including a BP/X bar, a classical bulge, a nuclear disk, and a main disk. The BP/X bar is not perfectly included in the input 3D density model, but BP/X-supporting orbits are picked through the fitting to the kinematic data. This is the first time a real barred galaxy has been modeled utilizing the Schwarzschild method including a 3D bar. Our model can be applied to a large number of nearby barred galaxies with IFU data, and it will significantly improve the previous models in which the bar is not explicitly included.

We present new measurements of the mean transmitted flux in the hydrogen Lyman-alpha and Lyman-beta forest using 27,008 quasar spectra from the Fourteenth Data Release (DR14) of the Extended Baryon Oscillation Spectroscopic Survey (eBOSS). Individual spectra are first combined into 16 composites with mean redshifts in the range of 2.8 < z < 4.9. We then apply Markov Chain Monte Carlo (MCMC) inference to produce a piecewise fit of the effective {\tau_{Ly\alpha}} (corrected for metal lines and optically thick absorptions) and relative {\Delta}{\tau_{Ly\beta}} optical depths. A detailed evaluation of our large data set shows a systematic offset towards lower values of {\tau_{Ly\alpha}} compared to recent results by Kamble et al. (2020) based on SDSS DR12.

Aims: To investigate the characteristics of the bar and inner disk in the collisional ring galaxy Cartwheel. Methods: We used the Integral Field Unit (IFU) observations with Multi-Unit Spectroscopic Explorer (MUSE) of the Very Large Telescope (VLT) to investigate the stellar kinematics, age, and nature of ionised gas in the inner region of the Cartwheel. We produced the stellar line of sight (LOS) velocity (V), velocity dispersion ($\sigma$), h$_3$ velocity moment, stellar population age, and emission-line maps of the galaxy using the Galaxy IFU Spectroscopy Tool (GIST) pipeline. Results: The observed nature of intensity, V, and $\sigma$ profiles altogether support the existence of a stellar bar as earlier revealed from near-infrared (NIR) $K_s$ band imaging. A weak correlation between V/$\sigma$ and h$_3$ is found within the bar radius, providing more kinematic evidence for a stellar bar which survived the drop-through collision. The overall weak anti-correlation between V/$\sigma$ and h$_3$ in the disk implies that the stellar orbits in the disk are less stable, which might be due to the impact of the collision. The mass-weighted age map of the galaxy shows that the stellar populations in the bar region are relatively older, with an increasing gradient from the bar edge to the centre, another evidence to signify that the bar was present before the galaxy underwent collision. We do not find an active galactic nuclei (AGN) from the BPT analysis of a central unresolved source reported earlier using NIR imaging. Our findings provide the preservation of the pre-collisional structures in the inner region of the Cartwheel, an important input to understanding the evolution of collisional galaxy systems, particularly investigating the pre-collisional central region for theoretical studies.

Low-metallicity very massive stars with an initial mass of $\sim 140$--$260\, {\rm M_\odot}$ are expected to end their lives as pair-instability supernovae (PISNe). The abundance pattern resulting from a PISN differs drastically from regular core-collapse supernova (CCSN) models and is expected to be seen in very metal-poor (VMP) stars of ${\rm[Fe/H]}\lesssim -2$. Despite the routine discovery of many VMP stars, the unique abundance pattern expected from PISNe has not been unambiguously detected. The recently discovered VMP star LAMOST J1010+2358, however, shows a peculiar abundance pattern that is remarkably well fit by a PISN, indicating the potential first discovery of a bonafide star born from gas polluted by a PISN. In this paper, we study the detailed nucleosynthesis in a large set of models of CCSN of Pop III and Pop II star of metallicity ${\rm[Fe/H]}=-3$ with masses ranging from $12$--$30\,{\rm M_\odot}$. We find that the observed abundance pattern in LAMOST J1010+2358 can be fit at least equally well by CCSN models of $\sim 12$--$14\,{\rm M_\odot}$ that undergo negligible fallback following the explosion. The best-fit CCSN models provide a fit that is even marginally better than the best-fit PISN model. We conclude the measured abundance pattern in LAMOST J1010+2358 could have originated from a CCSN and therefore cannot be unambiguously identified with a PISN given the set of elements measured in it to date. We identify key elements that need to be measured in future detections in stars like LAMOST J1010+2358 that can differentiate between CCSN and PISN origin.

During observations of the Galactic Plane Pulsar Snapshot (GPPS) survey by the Five-hundred-meter Aperture Spherical radio Telescope (FAST), varying subpulses drifting of PSR J1857+0057 is detected. The following-up observation confirms the quasi-regularly changes of the drifting rate about every 50 periods. We determine the drift rate $D$ through a linear fit to the pulse-central longitudes of subpulses in a drifting band, and determine $P_3$ from the cross-points of two fitted lines at the zero longitude for two neighbored drifting bands. The low frequency modulation of about every 50 periods is found on variations of not only pulse intensity but also drift parameters. In most of low frequency modulation cycles, the integrated pulse intensity $I$ and the absolute drift rate $|D|$ tend to increase first and then decrease, and the drifting periodicity $P_3$ varies just in the opposite. In addition, the phase-forward intensity-enhancement is observed in many modulation cycles. Based on our polarization data, the average PA curve for pulses with a smaller $|D|$ and larger $P_3$ is slightly steep in the leading edge of pulse profile compared with that of the fully averaged profile.

Near the center of the Puppis A SNR a series of nested optically emitting rings of high velocity ejecta (known as `the Swirl') were identified several decades ago by Winkler et al. (1989). To date no follow-up observations of these rings have been published, and their physical origin has remained a mystery. We present results of integral field spectroscopy of the Swirl using the Wide Field Integral Spectrograph (\wifes) on the 2.3\,m telescope at Siding Spring Observatory in Australia. The outermost ring exhibits a nitrogen-rich spectrum blueshifted to 1350 km/s, with smaller blueshifted rings within the first exhibiting mostly oxygen-rich spectra moving at 1000 km/s and 750 km/s. The structures are connected by material of intermediate velocity and variable composition, including sulfur-rich material. The Swirl is turbulent and shock excited, and contains as much as 0.5 M$_{\odot}$ of metal-rich material. The chemical composition and exclusively blueshifted radial velocities of the Swirl are consistent with progressively deeper nucleosynthetic layers in a massive progenitor star. We suggest the possibility that the Swirl marks a `funnel' carved into the supernova ejecta by a close, massive binary companion at the moment of explosion.

Recent data released by James Webb Space Telescope (JWST) and, somewhat earlier, the data presented by Hubble Space Telescope (HST) are commonly understood as a strong indication for breaking of the canonical $\Lambda$CDM cosmology. It is argued in the presented work that massive primordial black holes (PBH) could seed galaxy and quasar formation in the very young universe as it has been conjectured in our paper of 1993 and resolve the tension induced by the JWST and the HST data with the standard cosmology. This point of view is presently supported by several recent works. The proposed mechanism of PBH formation leads to the log-normal mass spectrum of PBHs and predicts abundant antimatter population of our Galaxy, Milky Way. Both these predictions are in excellent agreement with astronomical observations.

Understanding the magnetic field sensitivity of Transition Edge Sensors (TESs) is vital in optimising the configuration of any magnetic shielding as well as the design of the TESs themselves. An experimental system has been developed to enable the investigation of the applied magnetic field direction on TES behaviour, and the first results from this system are presented. In addition, measurements of the effect of applied magnetic field magnitude on both supercurrent and bias current are presented. The extent to which the current theoretical framework can explain the results is assessed and finally, the impact of this work on the design of TESs and the design of magnetic shielding is discussed.

Context: We are testing strong equivalence principle with planetary ephemerides in the frame of the Brans-Dicke class of scalar tensor theories. Aims: In this work, we apply our recently proposed Bayesian methodology on the Brans-Dicke case, with an emphasis on the issue of the strong equivalence principle. Methods: We compare the posterior distributions obtained fully consistently in this case with the preceding Parametrized Post-Newtonian (PPN) integrations in planetary ephemerides, which did not incorporate potential violations of the strong equivalence principle. Results: We observe a shift in the confidence levels of the posteriors obtained. We interpret this shift as marginal evidence suggesting that the effect of the Strong Equivalence Principle violation can no longer be neglected in planetary ephemerides. We also notably report that the constraint on the Brans-Dicke parameter with planetary ephemerides is getting closer to the figure reported from the Cassini spacecraft alone, but also to the constraints from pulsars. We anticipate that data from future spacecraft missions, such as BepiColombo, will significantly enhance the constraint with planetary ephemerides.

The changing magnetic fields of the Sun are generated and maintained by a solar dynamo, the exact nature of which remains an unsolved fundamental problem in solar physics. Our objective in this paper is to investigate the role and impact of converging flows toward Bipolar Magnetic Regions (BMR inflows) on the Sun's global solar dynamo. These flows are large scale physical phenomena that have been observed and so should be included in any comprehensive solar dynamo model. We have augmented the Surface flux Transport And Babcock LEighton (STABLE) dynamo model to study the nonlinear feedback effect of BMR inflows with magnitudes varying with surface magnetic fields. This fully 3D realistic dynamo model produces the sunspot butterfly diagram and allows a study of the relative roles of dynamo saturation mechanisms such as tilt angle quenching and BMR inflows. The results of our STABLE simulations show that magnetic field dependent BMR inflows significantly affect the evolution of the BMRs themselves and result in a reduced buildup of the global poloidal field due to local flux cancellation within the BMRs, to an extent that is sufficient to saturate the dynamo. As a consequence, for the first time, we have achieved fully 3D solar dynamo solutions in which BMR inflows alone regulate the amplitudes and periods of the magnetic cycles.

We present relativistic magnetohydrodynamic modelling of jets running into hydrostatic, spherically symmetric cluster atmospheres. For the first time in a numerical simulation, we present model cluster atmospheres based upon the Universal Pressure Profile (UPP), incorporating a temperature profile for a typical self-similar atmosphere described by only one parameter - $M_{500}$. We explore a comprehensive range of realistic atmospheres and jet powers and derive dynamic, energetic and polarimetric data which provide insight into what we should expect of future high-resolution studies of AGN outflows. From the simulated synchrotron emission maps which include Doppler beaming we find sidedness distributions that agree well with observations. We replicated a number of findings from our previous work, such as higher power jets inflating larger aspect-ratio lobes and the cluster environment impacting the distribution of energy between the lobe and shocked regions. Comparing UPP and $\beta$-profiles we find that the cluster model chosen results in a different morphology for the resultant lobes with the UPP more able to clear lobe material from the core; and that these different atmospheres influence the ratio between the various forms of energy in the fully developed lobes. This work also highlights the key role played by Kelvin-Helmholtz (KH) instabilities in the formation of realistic lobe aspect-ratios. Our simulations point to the need for additional lobe-widening mechanisms at high jet powers, for example jet precession. Given that the UPP is our most representative general cluster atmosphere, these numerical simulations represent the most realistic models yet for spherically symmetric atmospheres.

The Low-Energy X-ray Polarization Detector (LPD) is one of the payloads in the POLAR-2 experiment, designed as an external payload for the China Space Station (CSS) deployment in early 2024. LPD is specifically designed to observe the polarization of Gamma-Ray Bursts (GRBs) prompt emission in the energy range of 2-10 keV, with a wide field of view (FoV) of 90 degrees in preliminary design. This observation is achieved using an array of X-ray photoelectric polarimeters based on gas pixel detectors. Due to the wide FoV configuration, the in-orbit background count rate in the soft X-ray range is high, while GRBs themselves also exhibit a high flux in this energy band. In order to assess the contribution of various background components to the total count rate, we conducted detailed simulations using the GEANT4 C++ package. Our simulations encompassed the main interactions within the instrument materials and provided insights into various background components within the wide FoV scheme. The simulation results reveal that among the background components, the primary contributors are the cosmic X-ray background (CXB) and bright X-ray sources. The total background count rate of LPD, after applying the charged particle background rejection algorithm, is approximately 0.55 counts/cm^2/s on average, and it varies with the detector's orbit and pointing direction. Furthermore, we performed comprehensive simulations and comparative analyses of the CXB and X-ray bright sources under different FoVs and detector pointings. These analyses provide valuable insights into the background characteristic for soft X-ray polarimeter with wide FoV.

Astrometric studies and orbital modeling of planetary moons have contributed significantly to advancing our understanding of their orbital dynamics. These studies require precise positions measured over extended periods. In this paper, we present the results of the 2021 Brazilian Jovian mutual phenomena campaign. The data correspond to eight events between Galilean satellites, in addition to a rare eclipse of Thebe, an inner satellite, totaling nine events. A geometric model along with the DE440/JUP365 ephemerides was used to reproduce the events and simulate the light curves. A Monte Carlo method and chi-squared statistics were used to fit the simulated light curves to the observations. The reflectance model adopted for our simulations was the complete version of the Oren-Nayer model. The average uncertainty of the relative positions of the Galilean satellites was 5 mas (15 km) and for the inner Thebe satellite 32 mas (96 km). The seven mutual events (nine independent observations) here analyzed represent and addition of 17% events (10% light curves) with respect to the PHEMU21 international campaign. Furthermore, our result of Thebe eclipse is only the second measurement published to date. Our results contribute to the ephemeris database, being fundamental to improving satellite orbits and thus minimizing their uncertainties.

We investigate exact and approximate techniques to calculate the emission of gravitational radiation from cosmic string loops in order to generate beam models covering the entire celestial sphere for a wide range of modes $m$. One approach entails summing over contributions of stationary and nearly-stationary points of individual, factorized, left- and right-moving modes. This ``multipoint method" generalizes traditional methods that rely on expansions around exact stationary points of mode products. A second complementary approach extends the method of steepest descent to generate an asymptotic description of the beam as $m \to \infty$. We present example calculations of the emission of power from cusp-containing loops and compare the results with those obtained by numerically exact techniques as well as by previous approaches. The multipoint method achieves its best results at an intermediate range of modes, improving over previous methods in terms of accuracy. It handles the emission from all regions of the loop not just those near cusps. We demonstrate this capability by making a detailed study of the ``pseudocusp" phenomenon.

The search for exoplanets has revealed a diversity of planetary system architectures, the vast majority of which diverge significantly from the template of the solar system. In particular, giant planets beyond the snow line are relatively rare, especially for low-mass stars, placing the solar system within a small category of systems with multiple giant planets at large separations. An exoplanetary system of note is that of HD 141399, consisting of a K dwarf host star that harbors four giant planets with separations extending to $\sim$4.5 AU. The architecture of the system creates a complex pattern of mean motion resonances and gravitationally perturbed regions that may exclude the presence of other planets, including within the Habitable Zone of the system. Here, we present the results of dynamical simulations that explore the interaction of the known planets of the system, their apsidal trajectories, resonance locations, and dynamical evolution. We further investigate the results of injecting Earth-mass planets and provide the regions of dynamical viability within the Habitable Zone where terrestrial planets may maintain long-term stability. We discuss these results in the context of the importance of giant planets for volatile delivery and planetary habitability considerations.

The ability to accurately predict the contrast achieved from high contrast imagers is important for efficient scheduling and quality control measures in modern observatories. We aim to consistently predict and measure the raw contrast achieved by SPHERE/IRDIS on a frame by frame basis to improve the efficiency and scientific yield with SPHERE at the Very Large Telescope (VLT).Contrast curves were calculated for over 5 years of archival data using the most common SPHERE/IRDIS coronagraphic mode in the H2/H3 dual band filter, consisting of approximately 80,000 individual frames. These were merged and interpolated with atmospheric data to create a large data-base of contrast curves with associated features. An empirical power law model for contrast, motivated by physical considerations, was then trained and finally tested on an out-of-sample test data set. At an angular separation of 300 mas, the contrast model achieved a mean (out-of-sample) test error of 0.13 magnitudes with the residual 5-95% percentiles between -0.23 and 0.64 magnitude respectively. The models test set root mean square error (RMSE) between 250-600 mas was between 0.31 - 0.40 magnitudes which is equivalent with other state-of-the-art contrast models presented in the literature. In general, the model performed best for targets between 5-9 G-band magnitude, with degraded performance for targets outside this range. This model is currently being incorporated into the Paranal SCUBA software for first level quality control and real time scheduling support.

With advancements in low-cost launchers and small interplanetary spacecraft, NASA has recognized the potential of small missions to perform focused planetary science investigations at Mars and Venus. The EscaPADE, part of the NASA SIMPLEx program will deliver two small spacecraft to elliptical orbits around Mars using the Photon spacecraft. Orbit insertion, particularly to low-circular orbits requires significant propellant, taking up a substantial fraction of the Photon wet mass and present a significant challenge for small missions. The large $\Delta$V requirements for low-circular orbit make it difficult to insert small satellites into these orbits even with the highly capable Photon, as the total $\Delta$V for Earth escape and orbit insertion exceeds its capability. Drag modulation aerocapture offers a promising alternative, using the atmospheric drag to obtain the large $\Delta$V. The study shows how the Photon when combined with drag modulation aerocapture can deliver small orbiters to low-circular orbits, enabling a wide range of small orbiter missions. Aerocapture eliminates the need for Photon to provide 2 to 3.5 km/s of $\Delta$V for orbit insertion, which translate into mass and cost savings, and can enable frequent low-cost small orbiters and small satellite constellations at Mars and Venus in the near future.

Fast radio bursts (FRBs) are immensely energetic millisecond-duration radio pulses. Observations indicate that nearby FRBs can be produced by both young stellar populations, as suggested by the detection of FRB 20200428 from a Galactic magnetar SGR 1935+2154, and old stellar populations, as suggested by the localization of the repeating source FRB 20200120E in a globular cluster of M81. Nevertheless, the burst energies of FRB 20200120E are significantly smaller than those of other cosmological FRBs, even falling below the energy of the Galactic event FRB 20200428. Additionally, its burst energy distribution displays a steep power law tail at high fluences. It is unclear whether this type of source can contribute to the cosmological FRB population. Here we report the detection of a burst from FRB 20200120E in 1.1-1.7 GHz, with a fluence of approximately 31.4 Jy ms, which is more than 44 times larger than the previous detected bursts 1.4 GHz frequencies and five times more energetic than FRB 20200428. It reaches one-third of the energy of the weakest burst from FRB 20121102A detected so far and is detectable at a distance exceeding 200Mpc. This suggests that globular clusters can host cosmological FRBs, and the currently localized FRB sample could contain FRBs from globular clusters. Together with SGR 1935+2154, these two most nearby sources support multiple progenitor sources for FRBs.

We report the first radial velocity spectroscopic study of the eclipsing period bouncer SDSS J105754.25+275947.5. Together with eclipse light curve modeling, we redetermined the system parameters and studied the accretion disk structure. We confirm that the system contains a white dwarf with $M_{\mathrm{WD}}=0.83(3) M_\odot$ and an effective temperature of 11,500(400)K. The mass of the secondary is $M_2 = 0.056 M_\odot$ with an effective temperature of T$_2$=2,100K or below. The system inclination is $i=84.3(6)$. The data is in good agreement with our determination of $K_1$ = 33(4) km s$^{-1}$. We estimate the mass transfer rate as $\dot{M}=$1.9(2)$\times 10^{-11} M_\odot yr^{-1}$. Based on an analysis of the SDSS and OSIRIS spectra, we conclude that the optical continuum is formed predominantly by the radiation from the white dwarf. The contribution of the accretion disk is low and originates from the outer part of the disk. The Balmer emission lines are formed in a plasma with $\log$ $N_0$ = 12.7 [cm$^{-1}$] and a kinetic temperature of T$\sim$10,000K. The size of the disk, where the emission lines are formed, expands up to $R_\mathrm{d,out}=0.29 R_\odot$. The inner part of the emission line forming region goes down to $R_\mathrm{d,in}\approx 2 R_\mathrm{WD}$ . The Doppler tomography and trailed spectra show the presence of a hot spot and a clumpy structure in the disk, with variable intensity along the disk position angle. There is an extended region at the side opposite the hot spot with two bright clumps caused more probably by non-Keplerian motion there.

We report a discovery of a large-scale bent radio jet in the merging galaxy cluster Abell 514 ($z = 0.071$). The radio emission originates from the two radio lobes of the AGN located near the center of the southern subcluster and extends towards the southern outskirts with multiple bends. Its peculiar morphology is characterized by a $400$-kpc ``bridge'', a $300$-kpc ``arc'', and a $400$-kpc ``tail'', which together contribute to its largest linear size of $\sim0.7$ Mpc. We find that both the flux and spectral features of the emission change with the distance from the AGN. Also, the ``bridge'' presents a $60\%$ polarized radio emission, which coincided with an X-ray cold front. Based on our multi-wavelength observations, we propose that A514 presents a clear case for the redistribution of an old AGN plasma due to merger-driven gas motions. We support our interpretation with idealized cluster merger simulations employing a passive tracer field to represent cosmic-ray electrons and find that merger-driven motions can efficiently create a cloud of these particles in the cluster outskirts, which later can be re-accelerated by the cluster merger shock and produce radio relics.

It is thought that solar energetic ions associated with coronal/interplanetary shock waves are accelerated to high energies by the diffusive shock acceleration mechanism. For this mechanism to be efficient, intense magnetic turbulence is needed in the vicinity of the shock. The enhanced turbulence upstream of the shock can be produced self-consistently by the accelerated particles themselves via streaming instability. Comparisons of quasi-linear-theory-based particle acceleration models that include this process with observations have not been fully successful so far, which has motivated the development of acceleration models of a different nature. The aim of this work is to test how well our self-consistent quasi-linear SOLar Particle Acceleration in Coronal Shocks (SOLPACS) simulation code, developed earlier to simulate proton acceleration in coronal shocks, models the particle foreshock region. We applied SOLPACS to model the energetic storm particle (ESP) event observed by the STEREO A spacecraft on November 10, 2012. In the simulations, all but one main input parameter of SOLPACS are fixed by the in-situ plasma measurements from the spacecraft. By comparing a simulated proton energy spectrum at the shock with the observed one, we were able to fix the last simulation input parameter related to the efficiency of particle injection to the acceleration process. A subsequent comparison of simulated proton time-intensity profiles in a number of energy channels with the observed ones shows a very good correspondence throughout the upstream region.

The recently identified source class of pulsar halos may be populated and bright enough at TeV energies to constitute a large fraction of the sources that will be observed with the Cherenkov Telescope Array (CTA), especially in the context of the planned Galactic Plane Survey (GPS). In this study, we examine the prospects offered by CTA for the detection and characterization of such objects. CTA will cover energies from 20 GeV to 300 TeV, bridging the ranges already probed with the Fermi Large Area Telescope and High Altitude Water Cherenkov Observatory, and will also have a better angular resolution than the latter instruments, thus providing a complementary look at the phenomenon. From simple models for individual pulsar halos and their population in the Milky Way, we examine under which conditions such sources can be detected and studied from the GPS observations. In the framework of a full spatial-spectral likelihood analysis, using the most recent estimates for the instrument response function and prototypes for the science tools, we derive the spectral and morphological sensitivity of the CTA GPS to the specific intensity distribution of pulsar halos. From these, we quantify the physical parameters for which pulsar halos can be detected, identified, and characterized, and what fraction of the Galactic population could be accessible. We also discuss the effect of interstellar emission and data analysis systematics on these prospects.

Gas giant planets are differentially rotating magnetic objects that have strong and complex interactions with their environment. In our Solar system, they interact with their numerous moons while exoplanets with very short orbital periods (hot Jupiters), interact with their host star. The dissipation of waves excited by tidal forces in their interiors shapes the orbital architecture and the rotational dynamics of these systems. Recently, astrometric observations of Jupiter and Saturn systems have challenged our understanding of their formation and evolution, with stronger tidal dissipation in these planets than previously predicted, in contrast to what appears to be weaker in gas giant exoplanets. These new constraints are motivating the development of realistic models of tidal dissipation inside these planets. At the same time, the Juno and Cassini space missions have revolutionised our knowledge of the interiors of Jupiter and Saturn, whose structure is a combination of stably stratified zones and convective regions. In this work, we present results of hydrodynamical calculations modelling tidal waves and their dissipation in Jupiter, taking for the first time the latest, state-of-the-art interior model of the planet. We performed 2D numerical simulations of linear tidal gravito-inertial waves that propagate and dissipate within Jupiter interior by taking into account viscous, thermal and chemical diffusions. This new model allows us to explore the properties of the dissipation and the associated tidal torque as a function of all the key hydrodynamical and structural parameters.

Dusty starless cores play an important role in regulating the initial phases of the formation of stars and planets. In their interiors, dust grains coagulate and ice mantles form, thereby changing the millimeter emissivities and hence the ability to cool. We mapped four regions with more than a dozen cores in the nearby Galactic filaments of Taurus and Perseus using the NIKA-2 camera at the IRAM 30-meter telescope. Combining the 1mm to 2mm flux ratio maps with dust temperature maps from Herschel allowed to create maps of the dust emissivity index beta1,2 at resolutions of 2430 and 5600a.u. in Taurus and Perseus, respectively. Here, we study the variation with total column densities and environment. Beta1,2 values at the core centers (Av=12-19mag) vary significantly between ~1.1 and 2.3. Several cores show a strong rise of beta1,2 from the outskirts at ~4mag to the peaks of optical extinctions, consistent with the predictions of grain models and the gradual build-up of ice mantles on coagulated grains in the dense interiors of starless cores.

We present a Bayesian inference method to characterise the dust emission properties using the well-known dust-\hi\ correlation in the diffuse interstellar medium at Planck frequencies $\nu \ge 217$\,GHz. We use the Galactic \hi\ map from the Galactic All-Sky Survey (GASS) as a template to trace the Galactic dust emission. We jointly infer the pixel-dependent dust emissivity and the zero level present in the Planck intensity maps. We use the Hamiltonian Monte Carlo technique to sample the multi-dimensional parameter space. We demonstrate that the methodology is unbiased when applied to realistic Planck sky simulations over a 7500 deg$^2$ area around the Southern Galactic pole. As an application on data, we analyse the Planck intensity map at 353 GHz to jointly infer the pixel-dependent dust emissivity at $\Nside=32$ resolution (1.8\deg\ pixel size) and the global offset. We find that the spatially varying dust emissivity has a mean of 0.031 $\MJysr (10^{20} \mathrm{cm^{-2}})^{-1}$ and $1\sigma$ standard deviation of 0.007 $\MJysr (10^{20} \mathrm{cm^{-2}})^{-1}$. The mean dust emissivity increases monotonically with increasing mean \hi\ column density. We find that the inferred global offset is consistent with the expected level of Cosmic Infrared Background (CIB) monopole added to the Planck data at 353 GHz. This method is useful in studying the line-of-sight variations of dust spectral energy distribution in the multi-phase interstellar medium.

Detecting any evolution of dimensionless in the ratios of physical quantities, such as the fine structure constant, would prove that the Weak Equivalence Principle is violated and lead to a paradigm shift in physics. High resolution spectroscopy of quasar absorption systems can be used to test cosmological variations in time and/or in space. A sample of 300 measurements using data from 8m class optical telescopes provides hints that such variations are indeed present in a form of a spatial dipole across the sky, although systematic effects could dominate. Two recent developments, one in instrumentation and the other in analysis methods, promise to produce a new sample of measurements free from all known systematic effects to test the tentative dipole.

Gamma-ray binaries are binary systems where the energy flux peaks in the gamma-ray energy band. They harbour a compact object (a neutron star or a black hole) orbiting around a massive star that provides a strong radiation field. It is believed that the gamma-ray emission from such objects can be strongly attenuated through the electron-positron pair production in gamma-gamma interactions. The importance of gamma-gamma absorption depends on the orbital phase and on the geometry of the system. In this work we propose a method of how the orbital parameters of gamma-ray binaries could be probed with TeV light curves that have imprinted features of gamma-gamma absorption.

We study galaxies in JADES Deep to study the evolution of the ionising photon production efficiency, $\xi_{\rm{ion}}$, observed to increase with redshift. We estimate $\xi_{\rm{ion}}$ for a sample of 677 galaxies at $z \sim 4 - 9$ using NIRCam photometry. Specifically, combinations of the medium and wide bands F335M-F356W and F410M-F444W to constrain emission lines that trace $\xi_{\rm{ion}}$: H$\alpha$ and [OIII]. Additionally, we use the spectral energy distribution fitting code \texttt{Prospector} to fit all available photometry and infer galaxy properties. The flux measurements obtained via photometry are consistent with FRESCO and NIRSpec-derived fluxes. Moreover, the emission-line-inferred measurements are in tight agreement with the \texttt{Prospector} estimates. We also confirm the observed $\xi_{\rm{ion}}$ trend with redshift and M$_{\rm{UV}}$, and find: $\log \xi_{\rm{ion}} (z,\text{M}_{\rm{UV}}) = (0.05 \pm 0.02)z + (0.11 \pm 0.02) \text{M}_{\rm{UV}} + (27.33 \pm 0.37)$. We use \texttt{Prospector} to investigate correlations of $\xi_{\rm{ion}}$ with other galaxy properties. We see a clear correlation between $\xi_{\rm{ion}}$ and burstiness in the star formation history of galaxies, given by the ratio of recent to older star formation, where burstiness is more prevalent at lower stellar masses. We also convolve our $\xi_{\rm{ion}}$ relations with luminosity functions from the literature, and constant escape fractions of 10 and 20\%, to place constraints on the cosmic ionising photon budget. By combining our results, we find that if our sample is representative of the faint low-mass galaxy population, galaxies with bursty star formation are efficient enough in producing ionising photons and could be responsible for the reionisation of the Universe.

With the observation of gravitational waves from merging compact binary systems, a new observing window of the universe has been opened. Most of the gravitational wave events currently detected are due to the merger of binary black hole systems. One way to better investigate such systems is to look for coincident emission in electromagnetic waves or neutrinos. For typical models of isolated binaries, no such emission is expected. However, one promising class of mergers is that of binary black holes in the accretion disk of active galactic nuclei. Such mergers potentially occur at high rates, since these environments naturally have high numbers of black holes, which can efficiently form binaries, merge rapidly, and potentially accrete matter fast due to the surrounding gas. Here, we propose a method to search for coincident gravitational wave and neutrino emission from the location of known AGN, using an unbinned maximum likelihood analysis, and apply it to currently available public data.

The question of the origin of the hard X-ray/soft gamma-ray emission in Centaurus A (Cen A) persists despite decades of observations. Results from X-ray instruments suggest a jet origin since the implied electron temperature (kT_e) would cause pair production runaway in the corona. In contrast, instruments sensitive to soft gamma-rays report electron temperatures indicating a corona origin may be possible. In this context, we analyzed archival INTEGRAL/IBIS-ISGRI and SPI data and observations from a 2022 Cen A monitoring program. Our analysis did not find any spectral variability. Thus we combined all observations for long-term average spectra, which were fit with a NuSTAR observation to study the 3.5 keV - 2.2 MeV spectrum. Spectral fits using a CompTT model found kT_e ~ 550 keV, near pair-production runaway. The spectrum was also well described by a log-parabola to model synchrotron self-Compton emission from the jet. Additionally, a spectral fit with the 12-year catalog Fermi/LAT spectrum using a log-parabola can explain the data up to ~ 3 GeV. Above ~ 3 GeV, a power-law excess is present, which has been previously reported in LAT/H.E.S.S. analysis. However, including a corona spectral component can also describe the data well. In this scenario, the hard X-rays/soft gamma-rays are due the corona and the MeV to GeV emission is due to the jet.

We reconsider the escape of high brightness coherent emission of Fast Radio Bursts (FRBs) from magnetars' magnetospheres, and conclude that there are numerous ways for the powerful FRB pulse to avoid nonlinear absorption. Sufficiently strong surface fields, $\geq 10\%$ of the quantum field, limit the waves' non-linearity to moderate values. For weaker fields, the electric field experienced by a particle is limited by a combined ponderomotive and parallel-adiabatic forward acceleration of charges by the incoming FRB pulse along the magnetic field lines newly opened during FRB/Coronal Mass Ejection (CME). As a result, particles surf the weaker front part of the pulse, experiencing low radiative losses, and are cleared from the magnetosphere for the bulk of the pulse to propagate. We also find: (i) for propagation across magnetic field, the O-mode suffers much smaller dissipation than the X-mode; (ii) quasi-parallel propagation suffers minimal dissipation; (iii) initial mildly relativistic radial plasma flow further reduces losses; (iv) for oblique propagation of a pulse with limited transverse size, the leading part of the pulse would ponderomotively sweep the plasma aside.

The Cherenkov Telescope Array will be the next generation ground-based gamma ray observatory in the energy range from a few tens of GeV to hundreds of TeV. It will be built on two sites, one for each hemisphere, to cover the entire sky. The observatory will consist of telescopes of three different sizes: large, medium and small, with primary reflectors of 23, 11.5 and 4.3 m in diameter, respectively. The Small-Sized Telescopes (SSTs) will focus on the highest energies; at least 37 (and up to 70) will be deployed at the southern site in Paranal, Chile, covering several square kilometers. They will have a Schwarzschild-Couder dual-mirror design, with a primary reflector of about 4 meters in diameter. This configuration leads to a compact camera, with a diameter of about 50 cm and a weight of less than 100 kg. Its focal plane consists of 2048 Silicon Photomultiplier pixels, each one read independently by a state-of-the-art full waveform readout. The camera design is now in the final stage and the first components are being tested. In this contribution we discuss the design choices, and present test results from latest developments.

In a very recent work, [1] claim that the scenario of temperature inhomogeneities proposed by [2] ($t2$ > 0) is not able to explain the O$^{2+}$/H$^{+}$ abundance discrepancy observed between the calculations based on the optical [OIII] collisional excited lines (CELs) and the OII recombination lines (RLs) in the star forming galaxy Mrk71. In this work, we show that conclusions of [1] depend on several assumptions on the absolute flux calibration, reddening correction and the adopted electron density. In fact, using the data of [1] in a different way and even considering their 1{\sigma} uncertainties, it is possible to reach the opposite conclusion, consistent with $t2$ = $0.097 ^{+0.008}_{-0.009}$. Therefore, the existence of temperature inhomogeneities causing the O$^{2+}$/H$^{+}$ abundance discrepancy in Mrk71 can not be ruled out.

Very-high-energy gamma-ray observations of the Galactic center (GC) show extended emission that is strongly correlated with the morphology of the central molecular zone (CMZ). The best explanation for that emission is a hadronic interaction between cosmic rays (CRs) and ambient gas, where a CR central and continuous source accelerates protons up to 1 PeV ("PeVatron"). However, current models assume very simplistic CR dynamics. Our goal is to verify if more realistic CR dynamics for the GC environment are consistent with current gamma-ray observations, and whether they could be constrained by upcoming observations with the Cherenkov Telescope Array (CTA). We generated synthetic gamma-ray maps using a CR transport model with spherical injection, different diffusion regimes (in and out of the CMZ), polar advection, and mono-energetic particles of 1 PeV, and including different CR populations injected from the Arches, Quintuplet, and nuclear clusters of young massive stars, plus supernova Sgr A East. We adopted two different 3D gas distributions consistent with the observed gas column density, either with or without an inner cavity. In order to reproduce the existing observations detected by the High Energy Stereoscopic System (HESS), a ring-like gas distribution, with its mass set by the standard Galactic CO-to-H$_2$ conversion factor, and CR acceleration from all relevant sources are required. For a conversion factor one order of magnitude lower, injection rates that are ten times higher are needed. We show that CTA will be able to differentiate between models with different CR dynamics, proton sources, and CMZ morphology, owing to its unprecedented sensitivity and angular resolution. More realistic CR dynamics suggest that the CMZ has a large inner cavity and that the GC PeVatron is a composite CR population accelerated by the Arches, Quintuplet, and nuclear star clusters, and Sgr A East.

Exploring exoplanets has transformed our understanding of the universe by revealing many planetary systems that defy our current understanding. To study their atmospheres, spectroscopic observations are used to infer essential atmospheric properties that are not directly measurable. Estimating atmospheric parameters that best fit the observed spectrum within a specified atmospheric model is a complex problem that is difficult to model. In this paper, we present a multi-target probabilistic regression approach that combines deep learning and inverse modeling techniques within a multimodal architecture to extract atmospheric parameters from exoplanets. Our methodology overcomes computational limitations and outperforms previous approaches, enabling efficient analysis of exoplanetary atmospheres. This research contributes to advancements in the field of exoplanet research and offers valuable insights for future studies.

A key outstanding question in star and planet formation is how far the initial mass function of stars and sub-stellar objects extends, and whether or not there is a cut-off at the very lowest masses. Isolated objects in the planetary-mass domain below 13 Jupiter masses, where not even deuterium can fuse, are very challenging to observe as these objects are inherently faint. Nearby star-forming regions provide the best opportunity to search for them though: while they are young, they are still relatively warm and luminous at infrared wavelengths. Previous surveys have discovered a handful of such sources down to 3--5 Jupiter masses, around the minimum mass limit established for formation via the fragmentation of molecular clouds, but does the mass function extend further? In a new James Webb Space Telescope near-infrared survey of the inner Orion Nebula and Trapezium Cluster, we have discovered and characterised a sample of 540 planetary-mass candidates with masses down to 0.6 Jupiter masses, demonstrating that there is indeed no sharp cut-off in the mass function. Furthermore, we find that 9\% of the planetary-mass objects are in wide binaries, a result that is highly unexpected and which challenges current theories of both star and planet formation.

Auroral radio emissions in planetary magnetospheres typically feature highly polarized, intense radio bursts, usually attributed to electron cyclotron maser (ECM) emission from energetic electrons in the planetary polar region that features a converging magnetic field. Similar bursts have been observed in magnetically active low-mass stars and brown dwarfs, often prompting analogous interpretations. Here we report observations of long-lasting solar radio bursts with high brightness temperature, wide bandwidth, and high circular polarization fraction akin to these auroral/exo-auroral radio emissions, albeit two to three orders of magnitude weaker than those on certain low-mass stars. Spatially, spectrally, and temporally resolved analysis suggests that the source is located above a sunspot where a strong, converging magnetic field is present. The source morphology and frequency dispersion are consistent with ECM emission due to precipitating energetic electrons produced by recurring flares nearby. Our findings offer new insights into the origin of such intense solar radio bursts and may provide an alternative explanation for auroral-like radio emissions on other flare stars with large starspots.

In cluster cosmology, cluster masses are the main parameter of interest. They are needed to constrain cosmological parameters through the cluster number count. As the mass is not an observable, a scaling relation is needed to link cluster masses to the integrated Compton parameters Y, i.e. the Sunyaev-Zeldovich observable (SZ). Planck cosmological results obtained with cluster number counts are based on a scaling relation measured with clusters at low redshift ($z$<0.5) observed in SZ and X-ray. In the SZ Large Program (LPSZ) of the NIKA2 collaboration, the scaling relation will be obtained with a sample of 38 clusters at intermediate to high redshift ($0.5<z<0.9$) and observed at high angular resolution in both SZ and X-ray. Thanks to analytical simulation of LPSZ-like samples, we take into account the LPSZ selection function and correct for its effects. Besides, we show that white and correlated noises in the SZ maps do not affect the scaling relation estimation.

MeV neutrinos are produced in many astrophysical transients, such as stellar collapses and high-energy jets, where they play a role in sustaining and cooling energetic explosions. Detecting these neutrinos from sources outside the Milky Way is very difficult due to the small neutrino-nucleon cross section at MeV. Nevertheless, the non-observation of MeV neutrinos from high-energy transients may provide useful constraints on related neutrino production mechanisms where significant MeV production is expected. The IceCube Neutrino Observatory, a cubic kilometer neutrino detector operating with nearly 100% uptime at the South Pole, is sensitive to bursts of MeV neutrinos from astrophysical sources in and beyond the Milky Way. In this work, we describe the MeV neutrino detection system of IceCube and show results from several categories of astrophysical transients.

We present the characterization and definitive flux calibration of the Far-Infrared Field Integral Line Spectrometer (FIFI-LS) instrument on-board SOFIA. The work is based on measurements made in the laboratory with an internal calibrator and on observations of planets, moons, and asteroids as absolute flux calibrators made during the entire lifetime of the instrument. We describe the techniques used to derive flat-fields, water vapor column estimates, detector linearity, spectral and spatial resolutions, and absolute flux calibration. Two sets of responses are presented, before and after the entrance filter window was changed in 2018 to improve the sensitivity at 52um, a wavelength range previously not covered by PACS on Herschel. The relative spectral response of each detector and the illumination pattern of the arrays of the FIFI-LS arrays are derived using the internal calibrator before each observational series. The linearity of the array response is estimated by considering observations of bright sources. We find that the deviation from linearity of the FIFI-LS arrays affects the flux estimations less than 1%. The flux calibration accuracy is estimated to be 15% or better across the entire wavelength range of the instrument. The limited availability of sky calibrators during each observational series is the major limiting factor of the flux calibration accuracy.

We present a detailed modelling study of CD-30$^{\circ}$11223 (CD-30), a hot subdwarf (sdB)-white dwarf (WD) binary identified as a double detonation supernova progenitor, using the open-source stellar evolution software MESA. We focus on implementing binary evolution models carefully tuned to match the observed characteristics of the system including $\log g$ and $T_{\rm eff}$. For the first time, we account for the structure of the hydrogen envelope throughout the modelling, and find that the inclusion of element diffusion is important for matching the observed radius and temperature. We investigate the two sdB mass solutions (0.47 and 0.54 $M_{\odot}$) previously proposed for this system, strongly favouring the 0.47 $M_{\odot}$ solution. The WD cooling age is compared against the sdB age using our models, which suggest an sdB likely older than the WD, contrary to the standard assumption for compact sdB-WD binaries. Subsequently, we propose a possible alternate formation channel for CD-30. We also perform binary evolution modelling of the system to study various aspects such as mass transfer, orbital period evolution and luminosity evolution. Our models confirm CD-30 as a double detonation supernova progenitor, expected to explode $\approx55$ Myr from now. The WD accretes a $\approx0.17$ $M_{\odot}$ thick helium shell that causes a detonation, leaving a 0.30 $M_{\odot}$ sdB ejected at $\approx$750 km/s. The final 15 Myr of the system are characterised by helium accretion which dominates the system luminosity, possibly resembling an AM CVn-type system.

The asymmetric drift (AD) tomography in different populations will be helpful for us to better understand the disk kinematics, dynamics and rotation curves. Using the common stars from the LAMOST and Gaia surveys as well as circular velocity of Gaia DR3, we qualitatively explore the asymmetric drift distribution of the Galactic disk from 8$-$16 \,kpc. In the $R-Z$ plane, we find the asymmetric drift near the plane of the Galactic disk is small, and then gradually increases with the increase of the vertical distance, which makes the asymmetric drift appear as a ``horn" shape in the $R-Z$ plane. Meanwhile, we reveal that high [$\alpha$/Fe] populations have larger asymmetric drift than that in the low [$\alpha$/Fe] populations. The asymmetric drift around the solar location V$_a$ = 6 km s$^{-1}$ and the asymmetric drift median value of the whole sample is 16 km s$^{-1}$. Moreover, we also find that the asymmetric drift median value in the north (20 km s$^{-1}$) of the Galactic disk is larger than that in the south (13 km s$^{-1}$), all errors are within 2 km s$^{-1}$. Furthermore, when we investigate the asymmetric drift of the Galactic disk in the mono-age stellar populations, we also find that the older stellar populations have larger asymmetric drift and velocity dispersion which is consistent with predictions of previous numerical models. Finally, based on the chemistry, we unveil that the average asymmetric drift of the thick disk is much higher than that of the thin disk.

The joint analysis of galaxy clustering and galaxy-shear cross-correlations (galaxy-galaxy lensing) in imaging surveys constitutes one of the main avenues to obtain cosmological information. Analyses from Stage III surveys have assumed constant galaxy bias and weak lensing magnification coefficients within redshift bins. We use simple models of bias and magnification evolution to show that plausible levels of evolution impact cosmological parameter inference significantly for Stage IV surveys and possibly for current datasets as well. The distance weighting factors in galaxy-galaxy lensing cause it to have a different effective mean redshift within a lens bin than galaxy clustering. If the evolution is not included carefully in the theory modeling, this produces an apparent de-correlation of clustering and lensing even on large scales and leads to biased cosmological constraints. The level of bias is sensitive to the redshift and the width of the lens redshift distributions: for magnitude-limited-like samples it is comparable to the statistical precision even for the full DES survey, and exceeds it for Rubin-LSST. We find that ignoring the evolution can lead to approximately $1\sigma$ biases in the cosmological constraints in future Rubin-LSST analyses. We describe how these effects can be mitigated from the modeling and data sides, in particular by using cross-correlations to constrain the evolution parameters. We also demonstrate that the combination of galaxy clustering and CMB lensing does not suffer from this problem, due to the different distance weighting.

Time-resolved linear polarization ($\Pi$) measurements of the prompt gamma-ray burst emission can reveal its dominant radiation mechanism. A widely considered mechanism is synchrotron radiation, for which linear polarization can be used to probe the jet's magnetic-field structure, and in turn its composition. In axisymmetric jet models the polarization angle (PA) can only change by $90^\circ$, as $\Pi$ temporarily vanishes. However, some time-resolved measurements find a continuously changing PA, which requires the flow to be non-axisymmetric in at least one out of its emissivity, bulk Lorentz factor or magnetic field. Here we consider synchrotron emission in non-axisymmetric jets, from an ultrarelativistic thin shell, comprising multiple radially-expanding mini-jets (MJs) or emissivity patches within the global jet, that yield a continuously changing PA. We explore a wide variety of possibilities with emission consisting of a single pulse or multiple overlapping pulses, presenting time-resolved and integrated polarization from different magnetic field configurations and jet angular structures. We find that emission from multiple incoherent MJs/patches reduces the net polarization due to partial cancellation in the Stokes plane. When these contain a large-scale ordered field in the plane transverse to the radial direction, $\Pi$ always starts near maximal and then declines over the single pulse or shows multiple highly polarized peaks due to multiple pulses. Observing $\Pi\lesssim40\%$ ($15\%$) integrated over one (several) pulse(s) will instead favor a shock-produced small-scale field either ordered in the radial direction or tangled in the plane transverse to it.

We use high-resolution zoom-in simulations to study the fueling of the central galaxies by gas accretion from cosmological filaments at high redshifts, z>=2. Their parent haloes with similar DM masses of log(M_vir/M})~11.65, have been chosen at z=6, 4, and 2, in high/low overdensity environments, with the goal of comparing evolution within similar M at different z, under dual action of cosmological accretion and galactic outflows -- forming the circumgalactic medium (CGM). We focus on the filamentary and diffuse gas accretion within few virial radii, R_vir, down to the central galaxy. Using a hybrid d-web/entropy method we have mapped the gaseous filaments, and invoking particle kinematics allowed us to separate inflows from outflows, thus resolving thermodynamic and kinematic signatures of the CGM. We find that (1) The CGM is multiphase and not in thermodynamic or dynamic equilibrium; (2) accretion rates via individual filaments display a lower accretion rate and densities at lower redshifts. The inflow velocities along the filaments decrease with redshift, z~ 6-2, from 200-30 kms^-1 by a factor of 2; (3) Temperature within the filaments increases inside R_vir, faster at lower redshifts, in tandem with decrease in the accretion rate; (4) The filaments show a complex structure along their spines: a core radial flow surrounded by a lower density envelope. The core exhibits an elevated density and lower temperature, with no obvious metallicity gradient in the filament cross sections. It also tends to separate the filament into different infall velocity regions and density cores, thus producing a spaghetti-type flow; (6) Inside the inner ~ 30\,h^-1 kpc, the filaments develop the Kelvin-Helmholtz instability which ablates and dissolves them, and triggers turbulence along the filament spine; (7) Finally, the galactic outflows affect mostly the inner ~ 0.5R_vir~ 100 h^-1 kpc of the CGM.

We present bolometric luminosity ($L_{\rm bol}$) and black hole (BH) mass ($M_{\rm BH}$) estimators based on mid-infrared (MIR) continuum luminosity (hereafter, $L_{\rm MIR}$) that are measured from infrared (IR) photometric data. The $L_{\rm MIR}$-based estimators are relatively immune from dust extinction effects, hence they can be used for dust-obscured quasars. To derive the $L_{\rm bol}$ and $M_{\rm BH}$ estimators, we use unobscured quasars selected from the Sloan Digital Sky Survey (SDSS) quasar catalog, which have wide ranges of $L_{\rm bol}$ ($10^{44.62}$--$10^{46.16}$\,$\rm erg\,s^{-1}$) and $M_{\rm BH}$ ($10^{7.14}$--$10^{9.69}$\,$M_{\odot}$). We find empirical relations between (i) continuum luminosity at 5100\,$\rm{\AA{}}$ (hereafter, L5100) and $L_{\rm MIR}$; (ii) $L_{\rm bol}$ and $L_{\rm MIR}$. Using these relations, we derive the $L_{\rm MIR}$-based $L_{\rm bol}$ and $M_{\rm BH}$ estimators. We find that our estimators allow the determination of $L_{\rm bol}$ and $M_{\rm BH}$ at an accuracy of $\sim$0.2\,dex against the fiducial estimates based on the optical properties of the unobscured quasars. We apply the $L_{\rm MIR}$-based estimators to SDSS quasars at $z \lesssim 0.5$ including obscured ones. The ratios of $L_{\rm bol}$ from the $L_{\rm MIR}$-based estimators to those from the optical luminosity-based estimators become larger with the amount of the dust extinction, and a non-negligible fraction ($\sim$15\,\%) of the SDSS quasars exhibits ratios greater than 1.5. This result suggests that dust extinction can significantly affect physical parameter derivations even for SDSS quasars, and that dust extinction needs to be carefully taken into account when deriving quasar properties.

We use high-resolution numerical simulations to follow the barred disk evolution in a suite of models with progressively more massive stellar bulges, with bulge-to-total (disk$+$bulge) mass ratios of $B/T\sim 0-0.25$, embedded in dark matter (DM) halos with the spin $\lambda \sim 0 - 0.09$. We focus on models with a sequence of initial rotational support for bulges, and analyze their spinup and spindown. We find that (1) the presence of a bulge affects the evolution of stellar bars, i.e., the timescale of bar instability, bar pattern speed and its decay, and the vertical buckling instability. The bar strength is nearly independent of $B/T$ in halos with spin $\lambda = 0$, and is suppressed by a factor $\sim 2$ for halos with $\lambda = 0.09$; (2) The main effect of the bulge is the destruction of the harmonic core which affects the buckling; (3) The bulge plays a minor role in the exchange of angular momentum between the barred disk and the DM halo, during its spinup and spindown; (4) Most interestingly, the buckling process triggers different response above/below the disk midplane, which anti-correlates with the bulge mass; (5) In spinning halos, the buckling process has a prolonged amplitude tail, extending by few Gyr, as verified by measuring distortions in the Laplace plane; (6) Furthermore, as verified by orbital spectral analysis, the bulge gains its spin from the bar mainly via the inner Lindblad resonance, while losing it via a number of resonances lying between the outer and inner Lindblad resonance.

We propose that spontaneous folding and molecular evolution of biopolymers are two universal aspects that must concur for life to happen. These aspects are fundamentally related to the chemical composition of biopolymers and crucially depend on the solvent in which they are embedded. We show that molecular information theory and energy landscape theory allow us to explore the limits that solvents impose on biopolymer existence. We consider 54 solvents, including water, alcohols, hydrocarbons, halogenated solvents, aromatic solvents, and low molecular weight substances made up of elements abundant in the universe, which may potentially take part in alternative biochemistries. We find that along with water, there are many solvents for which the liquid regime is compatible with biopolymer folding and evolution. We present a ranking of the solvents in terms of biopolymer compatibility. Many of these solvents have been found in molecular clouds or may be expected to occur in extrasolar planets.

We study the Hartle-Hawking no-boundary proposal in the framework of Ho\v{r}ava-Lifshitz gravity. The former is a prominent hypothesis that describes the quantum creation of the universe, while the latter is a potential theory of quantum gravity that ensures renormalizability and unitarity, at least in the so-called projectable version. For simplicity, we focus on a global universe composed of a set of local universes each of which is closed, homogeneous and isotropic. Although applying the no-boundary proposal to Ho\v{r}ava-Lifshitz gravity is not straightforward, we demonstrate that the proposal can be formulated within the Ho\v{r}ava-Lifshitz gravity utilizing the Lorentzian path integral formulation of quantum gravity. In projectable Ho\v{r}ava-Lifshitz gravity, the no-boundary wave function of the global universe inevitably contains entanglement between different local universes induced by ``dark matter as integration constant''. On the other hand, in the non-projectable version, the no-boundary wave function of the global universe is simply the direct product of wave functions of each local universe. We then discuss how the no-boundary wave function is formulated under Dirichlet and Robin boundary conditions. For the Dirichlet boundary condition, we point out that its on-shell action diverges due to higher-dimensional operators, but this problem can in principle be ameliorated by taking into account the renormalization group flow. However, utilizing the Picard-Lefschetz theory to identify the relevant critical points and performing the complex lapse integration, we find that only the tunneling wave function can be obtained, as in the case of general relativity. On the other hand, for the Robin boundary condition with a particular imaginary Hubble expansion rate at the initial hypersurface, the no-boundary wave function can be achieved in the Ho\v{r}ava-Lifshitz gravity.

We study the problem of the gravitational collapse of an object as seen by an external observer. We assume that the resultant spacetime is a match of an external Vaidya spacetime with an interior Friedmann-Lema\^itre-Robertson-Walker (FRLW) spacetime of any spatial curvature and with a scalar field both minimally and non-minimally coupled to the metric. With the goal of studying a contracting (collapsing) object, for the initial moment of observation we take that its energy density and pressure are positive, that there are no trapping surfaces, and that the null energy condition (NEC) and the strong energy condition (SEC) are fulfilled. We show that there are many cases where singularities could be avoided for both the minimal and non-minimal couplings, although the contexts for so are very different in both cases. For the minimal coupling, the avoidance of singularities could happen either through evaporation or altogether, triggered by a violation of the SEC for a period of time. For the non-minimal coupling, the complete singularity avoidance happens only if evaporation takes place, and a temporary violation of the SEC does not thwart the formation of singularities. The above results show the relevance of the global (the whole spacetime) validity of energy conditions for the singularity theorems to be applicable; otherwise, the fate of a collapsing star is not known a priori. At the same time, the surface behavior of a collapsing body offers partial diagnostics of what happens in the inaccessible regions of spacetime to external observers. Our analyses suggest that a bounce behavior of the surface of the initially collapsing object is a fingerprint of the SEC violation in its interior, and that could be due to the existence of scalar fields there.

The pursuit of unraveling the true essence of dark energy has become an immensely captivating endeavor in modern cosmology. Alongside the conventional cosmological constant approach, a diverse range of ideas has been proposed, encompassing scalar field-based models and various modified gravity approaches. A particularly intriguing notion involves exploring scalar field dark energy models within quantum gravitationally motivated cosmologies, with non-canonical theories standing out as a prominent candidate in this context. Hence, in this work, we investigate three widely recognized non-canonical scalar field dark energy models: phantom, quintom, and DBI dark energy models. By employing the Goriely-Hyde procedure, we demonstrate the presence of singularities in both finite and infinite time within these frameworks. and that these singularities can manifest regardless of the system's initial conditions. Moreover, we further establish how cosmological singularities of types I-IV can arise in all of these models. The work goes to show that non-canonical regimes for dark energy can allow for most of the prominent cosmological singularities for a variety of models.

Organic molecular solids can exhibit rich phase diagrams. In addition to structurally unique phases, translational and rotational degrees of freedom can melt at different state points, giving rise to partially disordered solid phases. The structural and dynamic disorder in these materials can have a significant impact on the physical properties of the organic solid, necessitating a thorough understanding of disorder at the atomic scale. When these disordered phases form at low temperatures, especially in crystals with light nuclei, the prediction of materials properties can be complicated by the importance of nuclear quantum effects. As an example, we investigate nuclear quantum effects on the structure and dynamics of the orientationally-disordered, translationally-ordered plastic phase of the acetylene:ammonia (1:1) co-crystal that is expected to exist on the surface of Saturn's moon Titan. Titan's low surface temperature (~90 K) suggests that the quantum mechanical behavior of nuclei may be important in this and other molecular solids in these environments. By using neural network potentials combined with ring polymer molecular dynamics simulations, we show that nuclear quantum effects increase orientational disorder and rotational dynamics within the acetylene:ammonia (1:1) co-crystal by weakening hydrogen bonds. Our results suggest that nuclear quantum effects are important to accurately model molecular solids and their physical properties in low temperature environments.

In this article, the implementation of black-bounce solutions in $f(R)$ theories is investigated. Black-bounce solutions are regular configurations of the static spherically symmetric space-time, containing both black holes and wormholes structures. In General Relativity (GR), black-bounce solution implies violation of the energy conditions. We investigate the same issue in $f(R)$ theories using two strategies: first, supposing a given form for the $f(R)$ function and then determining the matter behavior; second, imposing a condition on the matter density and obtaining the resulting $f(R)$ function. In all cases, a given structure for the metric functions is supposed. Violation of the energy conditions still occur but they are less severe than in the corresponding GR cases. We propose a zero-density model that has horizons, which differs from the GR case. We also propose a model with positive energy density and show that $\rho+p_r>0$, which was not the case in GR.

This study delves into modified gravity theories that are equivalent to General Relativity but involve the torsion or non-metricity scalar instead of the curvature scalar. Specifically, we focus on $f(Q,T)$ gravity, which entails an arbitrary function of the non-metricity scalar $Q$ non-minimally coupled to the trace of the stress-energy tensor $T$. We investigate the functional form $f(Q,T)=f(Q)+f(T)$, where $f(Q) =Q+\alpha\,Q^2$ represents the Starobinsky model in $f(Q)$ gravity and $f(T)=2\,\gamma\,T$, with $\alpha$ and $\gamma$ are constants. To obtain solutions for the Friedmann equations, we introduce the concept of a constant jerk and employ its definition to trace the evolution of other kinematic variables, including the deceleration parameter, energy density, EoS parameter, and various energy conditions. These analyses serve to validate the proposed model. We constrain our constant jerk model using the most available Pantheon set of data, the Hubble set of data, and the BAO set of data. Further, we employ $Om(z)$ diagnostic as a means to differentiate between different theories of dark energy. Throughout our examination, all cosmological parameters under scrutiny consistently indicate an accelerating Universe.

This study investigates the application of a novel method for testing quantum gravitational corrections, arising from the non-commutative space-time and Generalized Uncertainty Principle approach with the Snyder model as an example. Utilizing seismic data, we establish constraints on the Snyder non-commutativity parameter $\beta_0$. Results indicate improved bounds compared to prior studies, with $\beta_0$ constrained to be less than $4.67\times 10^{44}$ for certain choice of phase space realizations and less than $1.56\times 10^{45}$ for another. This approach demonstrates the potential for using Earth's empirical data to refine constraints on quantum space-time models.

We construct a new cosmological holographic dark energy scenario based on Loop Quantum Gravity inspired entropy, instead of the standard Bekenstein-Hawking one. The former is an extended black-hole entropy that arises from non-extensive statistics and quantum geometry and is quantified by a new dimensionless parameter $q$, which possesses standard holographic dark energy as a particular sub-case. In the future event horizon as the Infrared cutoff, we provide a simple differential equation for the dark energy density parameter, as well as an analytical expressions for the corresponding equation-of-state and deceleration parameters. We show that the scenario at hand can describe successfully the usual thermal history of the Universe, with the sequence of matter and dark-energy epochs, while the transition to acceleration takes place at $z\approx 0.6$. Additionally, according to the value of the new entropic parameter $q$, the dark energy equation-of-state parameter can have a rich behavior, and it can be quintessence-like, phantom-like, or experience the phantom-divide crossing.

In General Relativity, there are only two polarizations for gravitational waves. However, up to six polarizations are possible in a generic metric theory of gravity. Therefore, measuring the polarization content of gravitational waves provides an efficient way to test theories of gravity. We analyze the sensitivity of a next-generation ground-based detector network to nontensorial polarizations. We present our method to localize GW signals in the time-frequency domain and construct the null stream for events with known sky locations. We obtain results based on simulations of binary neutron star mergers in a five-detector network. For a single event at a luminosity distance $D_L=100$ Mpc, the smallest amplitude for detection of scalar and vector modes relative to tensor modes are respectively $A_{s}=0.04$ and $A_{v}=0.013$. For multiple events in an averaged observing run of 10 years, the detection limits are $A_s=0.05$ and $A_v=0.02$. If we are fortunate, a few strong events might significantly improve the limits.