Papers for Tuesday, Nov 19 2024

There are now thousands of single-planet systems observed to exhibit transit timing variations (TTVs), yet we largely lack any interpretation of the implied masses responsible for these perturbations. Even when assuming these TTVs are driven by perturbing planets, the solution space is notoriously multi-modal with respect to the perturber's orbital period and there exists no standardized procedure to pinpoint these modes, besides from blind brute force numerical efforts. Using $N$-body simulations with $\texttt{TTVFast}$ and focusing on the dominant periodic signal in the TTVs, we chart out the landscape of these modes and provide analytic predictions for their locations and widths, providing the community with a map for the first time. We then introduce an approach for modeling single-planet TTVs in the low-eccentricity regime, by splitting the orbital period space into a number of uniform prior bins over which there aren't these degeneracies. We show how one can define appropriate orbital period priors for the perturbing planet in order to sufficiently sample the complete parameter space. We demonstrate, analytically, how one can explain the numerical simulations using first-order near mean-motion resonance super-periods, the synodic period, and their aliases -- the expected dominant TTV periods in the low-eccentricity regime. Using a Bayesian framework, we then present a method for determining the optimal solution between TTVs induced by a perturbing planet and TTVs induced by a moon.

Galaxies at redshift $z\sim 1-2$ display high star formation rates (SFRs) with elevated cold gas fractions and column densities. Simulating a self-regulated ISM in a hydrodynamical, self-consistent context, has proven challenging due to strong outflows triggered by supernova (SN) feedback. At sufficiently high gas column densities, and in the absence of magnetic fields, these outflows prevent a quasi-steady disk from forming at all. To this end, we present GHOSDT, a suite of magneto-hydrodynamical simulations that implement ISM physics at high resolution. We demonstrate the importance of magnetic pressure in the stabilization of gas-rich star-forming disks. We show that a relation between the magnetic field and gas surface density emerges naturally from our simulations. We argue that the magnetic field in the dense, star-forming gas, may be set by the SN-driven turbulent gas motions. When compared to pure hydrodynamical runs, we find that the inclusion of magnetic fields increases the cold gas fraction and reduces the disc scale height, both by up to a factor of $\sim 2$, and reduces the star formation burstiness. In dense ($n>100\;\rm{cm}^{-3}$) gas, we find steady-state magnetic field strengths of 10--40 $\mu$G, comparable to those observed in molecular clouds. Finally, we demonstrate that our simulation framework is consistent with the Ostriker & Kim (2022) Pressure Regulated Feedback Modulated Theory of star formation and stellar Feedback.

We present an approach that can be utilized in order to account for the covariate shift between two datasets of the same observable with different distributions, so as to improve the generalizability of a neural network model trained on in-distribution samples (IDs) when inferring cosmology at the field level on out-of-distribution samples (OODs) of {\it unknown labels}. We make use of HI maps from the two simulation suites in CAMELS, IllustrisTNG and SIMBA. We consider two different techniques, namely adversarial approach and optimal transport, to adapt a target network whose initial weights are those of a source network pre-trained on a labeled dataset. Results show that after adaptation, salient features that are extracted by source and target encoders are well aligned in the embedding space, indicating that the target encoder has learned the representations of the target domain via the adversarial training and optimal transport. Furthermore, in all scenarios considered in our analyses, the target encoder, which does not have access to any labels ($\Omega_{\rm m}$) during adaptation phase, is able to retrieve the underlying $\Omega_{\rm m}$ from out-of-distribution maps to a great accuracy of $R^{2}$ score $\ge$ 0.9, comparable to the performance of the source encoder trained in a supervised learning setup. We further test the viability of the techniques when only a few out-of-distribution instances are available and find that the target encoder still reasonably recovers the matter density. Our approach is critical in extracting information from upcoming large scale surveys.

Quenching of star-formation plays a fundamental role in galaxy evolution. This process occurs due to the removal of the cold interstellar medium (ISM) or stabilization against collapse, so that gas cannot be used in the formation of new stars. In this paper, we study the effect of different mechanisms of ISM removal. In particular, we revised the well-known Baldwin-Philips-Terlevich (BPT) and $\mathrm{EW_{H\alpha}}$ vs. $\mathrm{[NII]/H\alpha}$ (WHAN) emission-line ratio diagnostics, so that we could classify all galaxies, even those not detected at some emission lines, introducing several new spectral classes. We use spectroscopic data and several physical parameters of 2409 dusty early-type galaxies in order to find out the dominant ionization source [active galactic nuclei (AGNs), young massive stars, hot low-mass evolved stars (HOLMES)] and its effect on the ISM. We find that strong AGNs can play a significant role in the ISM removal process only for galaxies with ages lower than $10^{9.4}$ yr, but we cannot rule out the influence of weak AGNs at any age. For older galaxies, HOLMES/planetary nebulae contribute significantly to the ISM removal process. Additionally, we provide the BPT and WHAN classifications not only for the selected sample but also for all 300000 galaxies in the GAMA fields.

We present images of IRAS~08235--4316 with the Dark Energy Camera Plane Survey (DECaPS; spanning 0.398--1.034$\,\mu$m, at ${\sim}1''$ resolution) and the Submillimeter Array (SMA; at 1.38\,mm/217\,GHz, at ${\sim}1.9''\times1.2''$ resolution), a YSO located in the Vela constellation near to the Puppis boundary, detected in a systematic search for new large/extended emission sources. The DECaPS data show an asymmetric bi--polar morphology with a large angular extent of ${\sim}7.1''$ separated by a dark lane, characteristic of highly--inclined protoplanetary disks and less-evolved YSOs with outflows. The SMA data show an extended continuum structure along the optical dark lane with a smaller angular extent of ${\sim}4.6''$. The detected $^{12}$CO J=2--1 emission tentatively shows a velocity gradient along the position angle of the dark lane/millimeter continuum, that may trace rotating gas. Additional $^{12}$CO emission is present which could trace infalling/outflowing gas, and/or a nearby gas cloud. We estimate a distance to IRAS~08235--4316 of at least ${\sim}191\,$pc. Supported by additional SED modelling, we infer IRAS~08235--4316 to be a newly discovered class~I YSO with an outflow, host to an embedded protoplanetary disk, with a large millimeter radius of ${\sim}440$\,au and dust mass ${\gtrsim}11\,M_\oplus$.

While supermassive black-hole (SMBH)-binaries are not the only viable source for the low-frequency gravitational wave background (GWB) signal evidenced by the most recent pulsar timing array (PTA) data sets, they are expected to be the most likely. Thus, connecting the measured PTA GWB spectrum and the underlying physics governing the demographics and dynamics of SMBH-binaries is extremely important. Previously, Gaussian processes (GPs) and dense neural networks have been used to make such a connection by being built as conditional emulators; their input is some selected evolution or environmental SMBH-binary parameters and their output is the emulated mean and standard deviation of the GWB strain ensemble distribution over many Universes. In this paper, we use a normalizing flow (NF) emulator that is trained on the entirety of the GWB strain ensemble distribution, rather than only mean and standard deviation. As a result, we can predict strain distributions that mirror underlying simulations very closely while also capturing frequency covariances in the strain distributions as well as statistical complexities such as tails, non-Gaussianities, and multimodalities that are otherwise not learnable by existing techniques. In particular, we feature various comparisons between the NF-based emulator and the GP approach used extensively in past efforts. Our analyses conclude that the NF-based emulator not only outperforms GPs in the ease and computational cost of training but also outperforms in the fidelity of the emulated GWB strain ensemble distributions.

Nearly all cool, evolved stars are solar-like oscillators, and fundamental stellar properties can be inferred from these oscillations with asteroseismology. Scaling relations are commonly used to relate global asteroseismic properties, the frequency of maximum power $\nu_{max}$ and the large frequency separation $\Delta \nu$, to stellar properties. Mass, radius, and age can then be inferred with the addition of stellar spectroscopy. There is excellent agreement between seismic radii and fundamental data on the lower red giant branch and red clump. However, the scaling relations appear to breakdown in luminous red giant stars. We attempt to constrain the contributions of the asteroseismic parameters to the observed breakdown. We test the $\nu_{max}$ and $\Delta \nu$ scaling relations separately, by using stars of known mass and radius in star clusters and the Milky Way's high-$\alpha$ sequence. We find evidence that the $\Delta \nu$-scaling relation contributes to the observed breakdown in luminous giants more than the $\nu_{max}$ relation. We test different methods of mapping the observed $\Delta \nu$ to the mean density via a correction factor, $F_{\Delta \nu}$ and find a $\approx 1 - 3\%$ difference in the radii in the luminous giant regime depending on the technique used to measure $F_{\Delta \nu}$. The differences between the radii inferred by these two techniques are too small on the luminous giant branch to account for the inflated seismic radii observed in evolved giant stars. Finally, we find that the $F_{\Delta \nu}$ correction is insensitive to the adopted mixing length, chosen by calibrating the models to observations of $T_{eff}$.

We aim to constrain the average star formation associated with neutral hydrogen gas reservoirs at cosmic noon. Using a unprecedented sample of 1716 high column density Damped Ly-$\alpha$ absorbers (DLAs) from the Sloan Digital Sky Survey with log($N$(HI) / cm$^{-2}$) $\ge$21, we generated the average Ly-$\alpha$ emission spectrum associated to DLAs, free from emission from the background quasar. We measured Ly$\alpha$ emission at $> 5.8\sigma$ level with luminosity $8.95\pm 1.54 \times \rm 10^{40}\ \text{erg}\ \text{s}^{-1}$ (corresponding to about 0.02 L$^{\star}$ at $z \sim$ 2-3) in systems with average log($N$(HI)/ $cm^{-2}$) $\approx$21.2 and at median redshift of $z \sim$ 2.64. The peak of the Ly$\alpha$ emission is apparently redshifted by $\sim$300 km s$^{-1}$ relative to the absorption redshift, which is seemingly due to suppression of blue Ly-$\alpha$ photons by radiative transfer through expanding gas. We infer that DLAs form stars with an average rate of (0.08 $\pm$ 0.01)/$\text{f}_\text{esc}\ \rm \text{M}_{\odot}\ \text{yr}^{-1}$, i.e, $\approx (0.54\pm 0.09)\rm \text{M}_{\odot}\ \text{yr}^{-1}$ for a typical escape fraction, $\text{f}_{\text{esc}} =0.15$, of Lyman-$\alpha$ emitting galaxies. DLA galaxies follows the star formation main sequence of star-forming galaxies at high redshift, suggesting that the DLA population is dominated by the lower mass end of Lyman-$\alpha$ emitting galaxies.

The precise characterization and mitigation of systematic effects is one of the biggest roadblocks impeding the detection of the fluctuations of cosmological 21cm signals. Missing data in radio cosmological experiments, often due to radio frequency interference (RFI), poses a particular challenge to power spectrum analysis as it could lead to the ringing of bright foreground modes in Fourier space, heavily contaminating the cosmological signals. Here we show that the problem of missing data becomes even more arduous in the presence of systematic effects. Using a realistic numerical simulation, we demonstrate that partially flagged data combined with systematic effects can introduce significant foreground ringing. We show that such an effect can be mitigated through inpainting the missing data. We present a rigorous statistical framework that incorporates the process of inpainting missing data into a quadratic estimator of the 21cm power spectrum. Under this framework, the uncertainties associated with our inpainting method and its impact on power spectrum statistics can be understood. These results are applied to the latest Phase II observations taken by the Hydrogen Epoch of Reionization Array, forming a crucial component in power spectrum analyses as we move toward detecting 21cm signals in the ever more noisy RFI environment.

We present a detailed analysis of EELG1002: a $z = 0.8275$ EELG identified within archival Gemini/GMOS spectroscopy as part of the COSMOS Spectroscopic Archive. Combining GMOS spectra and available multi-wavelength photometry, we find EELG1002 is a low-mass ($10^{7 - 8}$ M$_\odot$), compact ($\sim 530$ pc), and bursty star-forming galaxy with mass doubling timescales of $\sim 5 - 15$ Myr. EELG1002 has record-breaking rest-frame [OIII]+H$\beta$ EW of $\sim 2800 - 3700$Å~which is $\sim 16 - 35 \times$ higher than typical $z \sim 0.8$ [OIII] emitters with similar stellar mass and even higher than typical $z > 5$ galaxies. We find no clear evidence of an AGN suggesting the emission lines are star formation driven. EELG1002 is chemically unevolved (direct $T_e$; $12+\log_{10} (\textrm{O/H}) \sim 7.5$ consistent with $z > 5$ galaxies at fixed stellar mass) and may be undergoing a first intense, bursty star formation phase analogous to conditions expected of galaxies in the early Universe. We find evidence for a highly energetic ISM ([OIII]/[OII] $\sim 11$) and hard ionizing radiation field (elevated [NeIII]/[OII] at fixed [OIII]/[OII]). Coupled with its compact, metal-poor, and actively star-forming nature, EELG1002 is found to efficiently produce ionizing photons with $\xi_{ion} \sim 10^{25.70 - 25.75}$ erg$^{-1}$ Hz and may have $\sim 10 - 20\%$ LyC escape fraction suggesting such sources may be important reionization-era analogs. We find dynamical mass of $\sim 10^9$ M$_\odot$ suggesting copious amounts of gas to support intense star-formation activity as also suggested by analogs identified in Illustris-TNG. EELG1002 may be an ideal low-$z$ laboratory of galaxies in the early Universe and demonstrates how archival datasets can support high-$z$ science and next-generation surveys planned with \textit{Euclid} and \textit{Roman}.

We emulate the Tolman-Oppenheimer-Volkoff (TOV) equations, including tidal deformability, for neutron stars using a novel hybrid method based upon the Dynamic Mode Decomposition (DMD) for the first time. This new method, which we call Star Log-extended eMulation (SLM), utilizes the underlying logarithmic behavior of the differential equations to enable accurate emulation of the nonlinear system. We show predictions for well-known phenomenological equations of state (EOS) with fixed parameters and with a freely-varying parametric Quarkyonic EOS. Our results produce a significant computational speed-up of $\approx 3 \times 10^4$ compared to high fidelity (HF) calculations using standard Runge-Kutta methods, providing an efficient emulator for the numerous TOV evaluations required by multi-messenger astrophysical frameworks that infer constraints on the EOS from neutron star mergers. The ability of the SLM algorithm to learn a mapping between parameters of the EOS and subsequent neutron star properties also opens up potential extensions for assisting in computationally prohibitive uncertainty quantification (UQ) for any type of EOS. The source code for the methods developed in this work will be openly available in a public GitHub repository for community modification and use.

Models and observations have demonstrated that Twisted Flux Ropes (TFRs) play a significant role in the structure and eruptive dynamics of active regions. Their role in the dynamics of the quiet Sun atmosphere on has remained elusive, their fundamental relevance emerging mainly from theoretical models (Amari et al. 2015), showing that they form and erupt as a result of flux cancellation. Here HINODE high-resolution photospheric vector magnetic field measurements are integrated with advanced environment reconstruction models: TFRs develop on various scales and are associated with the appearance of mesospots. The developing TFRs contain sufficient free magnetic energy to match the requirements of the recently observed "campfires" discovered by Solar Orbiter in the quiet Sun. The free magnetic energy is found to be large enough to trigger eruptions while the magnetic twist large enough to trigger confined eruptions, heating the atmosphere. TFRs are also connected to larger scale magnetic fields such as supergranulation loops, allowing the generation of Alfvén waves at the top of the chromosphere that can propagate along them. High-resolution magnetohydrodynamic simulations, incorporating subsurface dynamo activity at an unprecedented 30 km spatial resolution, confirm that TFRs are ubiquitous products of the permanent small scale dynamo engine that feeds their formation, destabilization, eruption via flux emergence, submergence and cancellation of their chromospheric feet, similar to the dynamics driving large scale eruptive events. Future investigations, especially with the Daniel K. Inouye Solar Telescope (DKIST) and Solar Orbiter will deepen our understanding of TFRs in the context of atmospheric heating.

We present JWST/MIRI low-resolution spectroscopy ($4.75-14~\mu$m) of the first known substellar companion, Gliese 229 Bab, which was recently resolved into a tight binary brown dwarf. Previous atmospheric retrieval studies modeling Gliese 229 B as a single brown dwarf have reported anomalously high carbon-to-oxygen ratios (C/O) of $\approx 1.1$ using $1-5~\mu$m ground-based spectra. Here, we fit the MIRI spectrum of Gliese 229 Bab with a two-component binary model using the Sonora Elf Owl grid and additionally account for the observed $K$ band flux ratio of the binary brown dwarf. Assuming the two brown dwarfs share the same abundances, we obtain $\rm C/O=0.65\pm0.05$ and $\rm [M/H]=0.00^{+0.04}_{-0.03}$ as their abundances ($2\sigma$ statistical errors), which are fully consistent with the host star abundances. We also recover the same abundances if we fit the MIRI spectrum with a single brown dwarf model, indicating that binarity does not strongly affect inferred abundances from mid-infrared data when the $T_\rm{eff}$ are similar between components of the binary. We measure $T_\rm{eff}=900^{+78}_{-29}~$K and $T_\rm{eff}=775^{+20}_{-33}~$K for the two brown dwarfs. We find that the vertical diffusion coefficients of $\log{K_\rm{zz}} \approx4.0$ are identical between the two brown dwarfs and in line with $\log{K_\rm{zz}}$ values inferred for isolated brown dwarfs with similar $T_\rm{eff}$. Our results demonstrate the power of mid-infrared spectroscopy in providing robust atmospheric abundance measurements for brown dwarf companions and by extension, giant planets.

Rocky planets in our Solar System, namely Mercury, Venus, Earth, Mars, and the Moon, which is generally added to this group due to its geological complexity, possess a solid surface and share a common structure divided into major layers, namely a silicate crust, a silicate mantle, and an iron-rich core. However, while all terrestrial planets share a common structure, the thickness of their interior layers, their bulk chemical composition, and surface expressions of geological processes are often unique to each of them. In this chapter we provide an overview of the surfaces and interiors of rocky planets in the Solar System. We list some of the major discoveries in planetary exploration and discuss how they have helped to answer fundamental questions about planetary evolution while at the same time opening new avenues. For each of the major planetary layers, i.e., the surface, the crust and lithosphere, the mantle, and the core, we review key geological and geophysical processes that have shaped the planets that we observe today. Understanding the similarities and differences between the terrestrial planets in the Solar System will teach us about the diversity of evolutionary paths a planet could follow, helping us to better understand our own home, the Earth.

We use the Monte Carlo For AGN (active galactic nucleus) Channel Testing and Simulation (McFACTS, this https URL) code to study the effect of AGN disk and nuclear star cluster parameters on predicted mass distributions for LIGO-Virgo-KAGRA (LVK) compact binaries forming in AGN disks. The assumptions we vary include the black hole (BH) initial mass function, disk model, disk size, disk lifetime, and the prograde-to-retrograde fraction of newly formed black hole binaries. Broadly we find that dense, moderately short-lived AGN disks are preferred for producing a $(q,\chi_{\rm eff})$ anti-correlation like those identified from existing gravitational wave (GW) observations. Additionally, a BH initial mass function (MF $\propto M^{-2}$) is preferred over a more top-heavy MF ($M^{-1}$). The preferred fraction of prograde-to-retrograde is $>90\%$, to produce results consistent with observations.

Since cosmic shear was first observed in 2000, it has become a key cosmological probe and promises to deliver exquisite dark energy constraints. However, shear is inferred from coherent distortions of galaxy shapes, and the relation between galaxy ellipticities and gravitational shear is a serious potential source of bias. To address this, we are developing a shear estimation method that makes no assumption on galaxy shapes, in order to avoid the shortcomings of a simulation-based shear calibration. Our method relies on the estimation of second moments on the image, and the evaluation of how second moments respond to a shear applied to the coordinate system, without altering the image itself, at variance with the Metacalibration method. We also evaluate analytically the noise bias due to the non-linearity of the estimator, and confront it with the bias derived from noisy image simulations, which allows a fast and precise noise bias correction.

Dark matter annihilation has the potential to leave an imprint on the properties of the first luminous structures at Cosmic Dawn as well as the overall evolution of the intergalactic medium (IGM). In this work, we employ a semi-analytic method to model dark matter annihilation during Cosmic Dawn (approximately redshift $z=20$ to $40$), examining potential modifications to IGM evolution as well as gas collapse, cooling, and star formation in mini-halos. Our analysis takes into account the effects of dark matter-baryon velocity offsets, utilizing the public 21cmvFAST code, and producing predictions for the 21cm global signal. The results from our simplified model suggest that dark matter annihilation can suppress the gas fraction in small halos and alter the molecular cooling process, while the impact on star formation might be positive or negative depending on parameters of the dark matter model as well as the redshift and assumptions about velocity offsets. This underscores the need for more comprehensive simulations of the effects of exotic energy injection at Cosmic Dawn as observational probes are providing us new insights into the process of reionization and the formation of first stars and galaxies.

We present theoretical predictions and extrapolations from observed data of the stellar halos surrounding central group/cluster galaxies and the transition radius between them and the intracluster or diffuse light. Leveraging the state-of-the-art semi-analytic model of galaxy formation, {\small FEGA} (\citealt{contini2024c}), applied to two dark matter-only cosmological simulations, we derive both the stellar halo mass and its radius. Using theoretical assumptions about the diffuse light distribution and halo concentration, we extrapolate the same information for observed data from the {\small VEGAS} survey (\citealt{capaccioli2015,iodice2021}). Our model, supported by observational data and independent simulation results, predicts an increasing transition radius with halo mass, a constant stellar halo-to-intracluster light ratio, and a stable stellar halo mass fraction with increasing halo mass. Specifically, we find that the transition radius between the stellar halo and the diffuse light ranges from 20 to 250 kpc, from Milky Way-like halos to large clusters, while the stellar halo mass comprises only a small fraction, between 7\% and 18\%, of the total stellar mass within the virial radius. These results support the idea that the stellar halo can be viewed as a transition region between the stars bound to the galaxy and those belonging to the intracluster light, consistent with recent observations and theoretical predictions.

The energy provided in the radioactive decay of thorium (Th) and uranium (U) isotopes, embedded in planetary mantles, sustains geodynamics important for surface habitability such as the generation of a planetary magnetic dynamo. In order to better understand the thermal evolution of nearby exoplanets, stellar photospheric abundances can be used to infer the material composition of orbiting planets. Here we constrain the intrinsic dispersion of the r-process element europium (Eu) (measured in relative abundance [Eu/H]) as a proxy for Th and U in local F, G, and K type dwarf stars. Adopting stellar-chemical data from two high quality spectroscopic surveys, we have determined a small intrinsic scatter of 0.025 dex in [Eu/H] within the disk. We further investigate the stellar anti-correlation in [Eu/$\alpha$] vs [$\alpha$/H] at late metallicities to probe in what regimes planetary radiogenic heating may lead to periods of extended dynamo collapse. We find that only near-solar metallicity stars in the disk have Eu inventories supportive of a persistent dynamo in attendant planets, supporting the notion of a ``metallicity Goldilocks zone'' in the galactic disk. The observed anti-correlation further provides novel evidence regarding the nature of r-processes injection by substantiating $\alpha$ element production is decoupled from Eu injection. This suggests either a metallicity-dependent r-process in massive core-collapse supernovae, or that neutron-star merger events dominate r-process production in the recent universe.

Gamma-ray bursts (GRBs) are intense pulses of high-energy emission associated with massive stars' death or compact objects' coalescence. Their multi-wavelength observations help verify the reliability of the standard fireball model. We analyze 14 GRBs observed contemporaneously in gamma-rays by the \textit{Fermi} Large Area Telescope (LAT), in X-rays by the \textit{Swift} Telescope, and in the optical bands by \textit{Swift} and many ground-based telescopes. We study the correlation between the spectral and temporal indices using closure relations according to the synchrotron forward-shock model in the stratified medium ($n \propto r^{-k}$) with $k$ ranging from 0 to 2.5. We find that the model without energy injection is preferred over the one with energy injection in all the investigated wavelengths. In gamma-rays, we only explored the $\nu > $ max\{$\nu_c,\nu_m$\} (SC/FC) cooling condition (where $\nu_c$ and $\nu_m$ are the cooling and characteristic frequencies, namely the frequencies at the spectral break). In the X-ray and optical bands, we explored all the cooling conditions, including $\nu_m < \nu < \nu_c$ (SC), $\nu_c < \nu < \nu_m$ (FC), and SC/FC, and found a clear preference for SC for X-rays and SC/FC for optical. Within these cooling conditions, X-rays exhibit the highest rate of occurrence for the density profile with $k = 0$, while the optical band has the highest occurrence for $k$ = 2.5 when considering no energy injection. Although we can pinpoint a definite environment for some GRBs, we find degeneracies in other GRBs.

Understanding mass, size, and surface mass density of giant molecular clouds (GMCs) in galaxies is key to insights into star formation processes. We analyze these in M33 using Herschel dust and archival IRAM 30m telescope data, compared to Milky Way CO data. A Dendrogram algorithm on a 2D dust map and a Xco factor map are used for M33 instead of a constant value. Dust and CO-derived values are similar, with mean radii of $\sim\,$$58\,$pc for the dust and $\sim\,$$68\,$pc for CO. Largest GMAs are about $150\,$pc in radius, similar to the Milky Way, suggesting a size-limiting process. M33 contains less massive, lower-density GMCs compared to the Milky Way. The highest mass GMCs observed in the Milky Way are mostly absent in M33. M33's mean surface mass density is much lower, due to the Milky Way's higher column densities despite similar GMC areas. No systematic gradients in M33's physical properties were found with galactocentric radius, but higher densities and masses near the center suggest increased star formation. In both galaxies, 30% of molecular mass is central. The GMC mass power-law spectrum index is $\alpha=2.3\pm0.1$ and $\alpha=1.9\pm0.1$ for dust and CO in M33, respectively. We conclude that M33 and Milky Way GMCs are mostly similar, though M33 lacks high-mass GMCs, with no clear explanation. GMC properties weakly depend on galactic environment, with stellar feedback as a factor needing further study.

We employ Maximum Likelihood Estimators to examine the Pantheon+ catalogue of Type Ia supernovae for large scale anisotropies in the expansion rate of the Universe. The analyses are carried out in the heliocentric frame, the CMB frame, as well as the Local Group frame. In all frames, the Hubble expansion rate in the redshift range 0.023 < z < 0.15 is found to have a statistically significant dipolar variation exceeding 1.5 km/s/Mpc, i.e. bigger than the claimed 1% uncertainty in the SH0ES measurement of the Hubble parameter H_0. The deceleration parameter too has a redshift-dependent dipolar modulation at >5 sigma significance, consistent with previous findings using the SDSSII/SNLS3 Joint Lightcurve Analysis catalogue. The inferred cosmic acceleration cannot therefore be due to a Cosmological Constant, but is probably an apparent (general relativistic) effect due to the anomalous bulk flow in our local Universe.

Giant radio galaxies (GRGs), a minority among the extended-jetted population, form in a wide range of jet and environmental configurations, complicating the identification of the growth factors that facilitate their attainment of megaparsec scales. This study aims to numerically investigate the hypothesized formation mechanisms of GRGs extending $\gtrsim 1$ Mpc to assess their general applicability. We employ triaxial ambient medium settings to generate varying levels of jet frustration and simulate jets with low and high power from different locations in the environment, formulating five representations. The emergence of distinct giant phases in all five simulated scenarios suggests that GRGs may be more common than previously believed, a prediction to be verified with contemporary radio telescopes. We find that different combinations of jet morphology, power, and the evolutionary age of the formed structure hold the potential to elucidate different formation scenarios. The simulated lobes are overpressured, prompting further investigation into pressure profiles when jet activity ceases, potentially distinguishing between relic and active GRGs. We observed a potential phase transition in giant radio galaxies, marked by differences in lobe expansion speed and pressure variations compared to their smaller evolutionary phases. This suggests the need for further investigation across a broader parameter space to determine if GRGs fundamentally differ from smaller RGs. Axial ratio analysis reveals self-similar expansion in rapidly propagating jets, with notable deviations when the jet forms wider lobes. Overall, this study emphasizes that multiple growth factors at work can better elucidate the current-day population of GRGs, including scenarios e.g., growth of GRGs in dense environments, GRGs of several megaparsecs, GRG development in low-powered jets, and the formation of X-shaped GRGs.

Tidal disruption events (TDEs) result from stars being gravitationally-scattered into low angular momentum orbits around massive black holes. We show that the short lifetimes of massive Population III stars at high redshifts could significantly suppress the volumetric TDE rate because they are too short-lived to reach disruption-fated orbits. However, this suppression can be alleviated if captured dark matter (DM) within stellar interiors provides an additional energy source, thereby extending stellar lifetimes. We find that this TDE rate revival is most pronounced for DM particles with mass $\mathcal{O}({\rm MeV})$, as this particle mass scale is optimal in the competing processes of DM accretion and evaporation in stars.

The increasing density of space objects in low-Earth orbit highlights the critical need for accurate orbit predictions to minimise operational disruptions. One significant challenge lies in accurately modelling the interaction of gas particles with the surfaces of these objects, as errors in aerodynamic coefficient modelling directly impact orbit prediction accuracy. Current approaches rely on empirical models, such as those by Sentman and Cercignani-Lampis-Lord, incorporating one or two adjustable parameters typically calibrated with orbital acceleration data. However, these models fall short in capturing essential gas-solid interaction processes, including multiple reflections, shadowing, and backscattering caused by surface roughness. We present a novel, physics-based gas-surface interaction model that utilises electromagnetic wave theory to account for macroscopic effects of surface roughness on gas particle scattering distributions. This approach not only offers a more accurate representation of gas-surface interactions but also allows parameter determination through a combination of ground-based surface roughness measurements and molecular dynamics simulations at the atomic scale. The model validity is tested across the entire parameter space using a test-particle Monte Carlo method on a simulated rough surface. Furthermore, it successfully reproduces experimental results from the literature on the scattering of Argon and Helium from smooth and rough Kapton and Aluminium surfaces. Finally, we demonstrate the model's impact on aerodynamic coefficients for simple geometric shapes, comparing the results with those from the Sentman and Cercignani-Lampis-Lord models. This comparison reveals that inconsistencies previously observed between these models and tracking data for spherical satellites can be attributed to surface roughness effects, which our model effectively accounts for.

Recently the galaxy matter density 4-point correlation function has been looked at to investigate parity violation in large scale structure surveys. The 4-point correlation function is the lowest order statistic which is sensitive to parity violation, since a tetrahedron is the simplest shape that cannot be superimposed on its mirror image by a rotation. If the parity violation is intrinsic in nature, this could give us a window into inflationary physics. However, we need to exhaust all other contaminations before we consider them to be intrinsic. Even though the standard Newtonian redshift-space distortions are parity symmetric, the full relativistic picture is not. Therefore, we expect a parity-odd trispectrum when observing in redshift space. We calculate the trispectrum with the leading-order relativistic effects and investigate in detail the parameter space of the trispectrum and the effects of these relativistic corrections for different parameter values and configurations. We also look at different surveys and how the evolution and magnification biases can be affected by different parameter choices.

Non-gravitational forces play surprising and, sometimes, centrally important roles in shaping the motions and properties of small planetary bodies. In the solar system, the morphologies of comets, the delivery of meteorites and the shapes and dynamics of asteroids are all affected by non-gravitational forces. Around other stars, non-gravitational forces affect the lifetimes of particles and their rates of radial transport within circumstellar disks. Unlike the gravitational force, which is a simple function of the well known separations and masses of bodies, the non-gravitational forces are frequently functions of poorly known or even unmeasurable physical properties. Here, we present order-of-magnitude descriptions of non-gravitational forces, with examples of their application.

We present the broadband spectral and timing properties of the atoll source 4U 1702-429 using two observations of AstroSat with the second one having simultaneous NICER data. For both observations, the spectra can be represented by a Comptonizing medium with a black body seed photon source which can be identified with the surface of the neutron star. A disk emission along with a distant reflection is also required for both spectra. For the first observation, the coronal temperature ($\sim 7$ keV) is smaller than the second ($\sim 13$ keV), and the disk is truncated at a larger radius, $\sim 150$ km, compared to the second, $\sim 25$ km, for an assumed distance of 7 kpc. A kHz QPO at $\sim 800$ Hz is detected in the first and is absent in the second observation. Modeling the energy-dependent r.m.s and time lag of the kHz QPO reveals a corona size of $\leq$ 30 km. A similar model can explain the energy dependence of the broadband noise at $\sim 10$ Hz for the second observation. The results suggest that kHz QPOs are associated with a compact corona surrounding the neutron star and may occur when the disk is truncated at large distances. We emphasize the need for more wide-band observations of the source to confirm these results.

The CubeSat X-ray observatory NinjaSat was launched on 2023 November 11 and has provided opportunities for agile and flexible monitoring of bright X-ray sources. On 2024 February 23, the NinjaSat team started long-term observation of the new X-ray source SRGA J144459.2$-$604207 as the first scientific target, which was discovered on 2024 February 21 and recognized as the sixth clocked X-ray burster. Our 25-day observation covered almost the entire decay of this outburst from two days after the peak at $\sim$100 mCrab on February 23 until March 18 at a few mCrab level. The Gas Multiplier Counter onboard NinjaSat successfully detected 12 Type-I X-ray bursts with a typical burst duration of $\sim$20 s, shorter than other clocked burster systems. As the persistent X-ray emission declined by a factor of five, X-ray bursts showed a notable change in its morphology: the rise time became shorter from 4.4(7) s to 0.3(3) s (1$\sigma$ errors), and the peak amplitude increased by 44%. The burst recurrence time $\Delta t_{\rm rec}$ also became longer from 2 hr to 10 hr, following the relation of $\Delta t_{\rm rec} \propto F_{\rm per}^{-0.84}$, where $F_{\rm per}$ is the persistent X-ray flux, by applying a Markov chain Monte Carlo method. The short duration of bursts is explained by the He-enhanced composition of accretion matter and the relation between $\Delta t_{\textrm{rec}}$ and $F_{\rm per}$ by a massive neutron star. This study demonstrated that CubeSat pointing observations can provide valuable astronomical X-ray data.

In February and March 2024, several Type I X-ray bursts from the accreting neutron star SRGA J144459.2$-$60420 were detected by multiple X-ray satellites, with the first reports coming from INTEGRAL and NinjaSat. These observations reveal that after exhibiting very regular behavior as a ``clocked" burster, the peak luminosity of the SRGA J144459.2$-$60420 X-ray bursts shows a gradual decline. The observed light curves exhibit a short plateau feature, potentially with a double peak, followed by a rapid decay in the tail-features unlike those seen in previously observed clocked bursters. In this study, we calculate a series of multizone X-ray burst models with various compositions of accreted matter, specifically varying the mass fractions of hydrogen ($X$), helium ($Y$), and heavier CNO elements or metallicity ($Z_{\rm CNO}$). We demonstrate that a model with higher $Z_{\rm CNO}$ and/or lower $X/Y$ compared to the solar values can reproduce the observed behavior of SRGA J144459.2$-$60420. Therefore, we propose that this new XRB is likely the first clocked burster with non-solar elemental compositions. Moreover, based on the X-ray burst light curve morphology in the decline phase observed by NinjaSat, a He-enhanced model with $X/Y \approx 1.5$ seems preferred over high-metallicity cases. We also give a brief discussion on the implications for the neutron star mass, binary star evolution, inclination angle, and the potential for a high-metallicity scenario, the last of which is closely related to the properties of the hot CNO cycle.

Stripped-envelope supernovae (SESNe) represent a significant fraction of core-collapse supernovae, arising from massive stars that have shed their hydrogen and, in some cases, helium envelopes. The origins and explosion mechanisms of SESNe remain a topic of active investigation. In this work, we employ radiative-transfer simulations to model the light curves and spectra of a set of explosions of single, solar-metallicity, massive Wolf-Rayet (WR) stars with ejecta masses ranging from 4 to 11 Msun, that were computed from a turbulence-aided and neutrino-driven explosion mechanism. We analyze these synthetic observables to explore the impact of varying ejecta mass and helium content on observable features. We find that the light curve shape of these progenitors with high ejecta masses is consistent with observed SESNe with broad light curves but not the peak luminosities. The commonly used analytic formula based on rising bolometric light curves overestimates the ejecta mass of these high-initial-mass progenitor explosions by a factor up to 2.6. In contrast, the calibrated method by Haynie et al., which relies on late-time decay tails, reduces uncertainties to an average of 20% within the calibrated ejecta mass this http URL, the He I 1.083 um line remains prominent even in models with as little as 0.02 Msun of helium. However, the strength of the optical He I lines is not directly proportional to the helium mass but instead depends on a complex interplay of factors such as 56Ni distribution, composition, and radiation field. Thus, producing realistic helium features requires detailed radiative transfer simulations for each new hydrodynamic model.

Transition region explosive events are characterized by non-Gaussian profiles of the emission lines formed at transition region temperatures, and they are believed to be manifestations of small-scale reconnection events in the transition region. We took a 3D self-consistent quiet-Sun model extending from the upper convection zone to the lower corona calculated using the MURaM code. We first synthesized the Si IV line profiles from the model and then located the profiles which show signatures of bi-directional flows. These tend to appear along network lanes, and most do not reach coronal temperatures. We isolated two hot (around 1 MK) events and one cool (order of 0.1 MK) event and examined the magnetic field evolution in and around these selected events. Furthermore, we investigated why some explosive events reach coronal temperatures while most remain cool. The field lines around two events reconnect at small angles, i.e., they undergo component reconnection. The third case is associated with the relaxation of a highly twisted flux rope. All of the three events reveal signatures in the synthesized EUI 174 Å images. The intensity variations in two events are dominated by variations of the coronal emissions, while the cool component seen in the respective channel contributes significantly to the intensity variation in one case. Comparing to the cool event, one hot event is embedded in regions with higher magnetic field strength and heating rates while the densities are comparable, and the other hot event is heated to coronal temperatures mainly because of the low density. Small-scale heating events seen in EUV channels of AIA or EUI might be hot or cool. Our results imply that the major difference between the events in which coronal counterparts dominate or not is the amount of converted magnetic energy and/or density in and around the reconnection region.

We report the detection of an extreme stellar prominence eruption on the M dwarf LAMOST J044431.62+235627.9, observed through time-domain H$\alpha$ spectroscopy with the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST). This prominence eruption was accompanied by a superflare lasting over 160.4 minutes. The H$\alpha$ line profile exhibits significant blue-wing enhancement during the impulsive phase and near the flare peak, with a projected bulk blueshift velocity of $-228\pm11$~km~s$^{-1}$ and a maximum blueshift velocity reaching $-605\pm15$~km~s$^{-1}$. Velocity analysis of the eruptive prominence at various heights above the stellar surface indicates that some of the projected ejection velocities along the line of sight exceed the corresponding escape velocities, suggesting a potential coronal mass ejection (CME). The equivalent width (EW) of the H$\alpha$ blue-wing enhancement in this eruption appears to be the largest observed to date and is comparable to the EW of the H$\alpha$ line profile during the quiescent phase of the host star. We performed a two-cloud modeling for the prominence and the associated flare, which suggests that the eruptive prominence has a mass ranging from $1.6 \times 10^{19}~\text{g}$ to $7.2 \times 10^{19}~\text{g}$. More importantly, the mass ratio of the erupting prominence to its host star is the largest among all reported stellar prominence eruptions/CMEs.

Abundant geomorphological and geochemical evidence of liquid water on the surface of early Mars during the late Noachian and early Hesperian periods needs to be reconciled with a fainter young Sun. While a dense CO2 atmosphere and related warming mechanisms are potential solutions to the early Mars climate problem, further investigation is warranted. Here, we complete a comprehensive survey of the warming potential of all known greenhouse gases and perform detailed calculations for 15 different minor gas species under early Martian conditions. We find that of these 15 species, H2O2, HNO3, NH3, SO2, and C2H4 cause significant greenhouse warming at concentrations of ~0.1 ppmv or greater. However, the most highly effective greenhouse gas species also tend to be more condensable, soluble and vulnerable to photolytic destruction. To provide a reference for future atmospheric evolution and photochemical studies, we have made our warming potential database freely available online.

Aims. We identify the possible dynamical connection between individual r-process-enhanced stars and the ultra-faint dwarf galaxy Reticulum II based on the current phase-space information for these stars and the dynamical mass-loss model of Reticulum II during its orbital motion for 11.5 Gyr of lookback time. The dynamical orbital modelling together with the chemical abundance analysis proved to be useful tools for the progenitor identification of the peculiar stars in our Galaxy. Methods. To reproduce the Reticulum II orbital mass loss, we used our high-precision N-body phi-GPU code to integrate almost 1 million stars into the system evolution inside a external Galactic potential. We also investigated the orbits of r-process-enhanced stars using the same code. Results. We present our Reticulum II dynamical modelling results in the context of the stars energies - angular momentum phase-space and phase-space overlapping of the currently observed r-process-enhanced stars with Reticulum II stellar tidal tails. Of the 530 r-stars known today, at least 93 are former members of the Reticulum II dynamical progenitor system.

In this work, we present a follow-up to our previous work where the concept of minimal Bipolar spherical harmonics (mBipoSH) functions was introduced as a natural basis for studying angular correlations in the non-statistical isotropic (nSI) Cosmic Microwave Background (CMB) sky. In this study, we extend the formalism of mBipoSH functions and apply it to analyze two sources of statistical isotropy (SI) violation-cosmic hemispherical asymmetry (CHA) and non-circular (NC) beam shapes. We present the analytical expression for mBipoSH functions and plot the corresponding angular correlation functions for these cases, addressing the $L=1$ and $L=2$ multipole statistical isotropy violations within the BipoSH basis. Our results confirm the effectiveness of the proposed approach, as it successfully captures and explains the observed angular correlations in the CMB sky.

Understanding the role of turbulence in shaping the interstellar medium (ISM) is crucial for studying star formation, molecular cloud evolution, and cosmic ray propagation. Central to this is the measurement of the sonic Mach number ($M_s$), which quantifies the ratio of turbulent velocity to the sound speed. In this work, we introduce a convolutional neural network (CNN)-based approach for estimating $M_s$ directly from spectroscopic observations. The approach leverages the physical correlation between increasing $M_s$ and the shock-induced small-scale fluctuations that alter the morphological features in intensity, velocity centroid, and velocity channel maps. These maps, derived from 3D magnetohydrodynamic (MHD) turbulence simulations, serve as inputs for the CNN training. By learning the relationship between these structural features and the underlying turbulence properties, CNN can predict $M_s$ under various conditions, including different magnetic fields and levels of observational noise. The median uncertainty of the CNN-predicted $M_s$ ranges from 0.5 to 1.5 depending on the noise level. While intensity maps offer lower uncertainty, channel maps have the advantage of predicting the 3D $M_s$ distribution, which is crucial in estimating 3D magnetic field strength. Our results demonstrate that machine-learning-based tools can effectively characterize complex turbulence properties in the ISM.

Matter-RADiation interaction SIMulation (MRADSIM) is an innovative modular software toolkit developed to simulate the effects of radiation on electronic components, human beings and various materials. It incorporates innovative features aimed at enhancing parametric precision, reducing computational time, and introducing supplementary functions for tailored calculations across diverse applications including the applications required for space missions. Notably, MRADSIM is distinguished as the pioneering simulation toolkit to integrate cutting-edge Artificial Intelligence and Machine Learning (AI/ML) algorithms, with the primary objective of effectively recognizing potential radiation-induced issues and facilitating the implementation of mitigation strategies to avert catastrophic failures in mission-critical systems, whether terrestrial or space-based. The distinctive attributes of MRADSIM, coupled with its early adoption by researchers from the National Institute for Nuclear Physics of Italy (INFN), significantly contribute to the toolkits added value.

It is shown that the presence of an interaction between dark energy and dark matter can induce a transmutation of quintessence from thawing to scaling freezing. The analysis is done in a Lagrangian approach where dark energy and dark matter are treated as spin zero fields. Remarkably, with the cosmological constraints on energy densities of dark matter and dark energy, such a transmutation can occur in the late universe and searchable in accumulating cosmological data by DESI and other dark energy-related experiments. We give a fit to the dark energy equation of state which can be used by experimental collaborations to search for this transmutation that can occur at redshifts up to $z=13$ depending on the interaction strength. A transmutation in the range $z=1-3$ is already within reach of current and near future experiments.

Understanding the dust content of galaxies, its evolution with redshift and its relationship to stars and star formation is fundamental for our understanding of galaxy evolution. Using the ALMA Lensing Cluster Survey (ALCS) wide-area band-6 continuum dataset ($\sim\,$110 arcmin$^2$ across 33 lensing clusters), we aimed at constraining the dust mass evolution with redshift, stellar mass and star formation rate (SFR). After binning sources according to redshift, SFR and stellar mass -- extracted from an HST-IRAC catalog -- we performed a set of continuum stacking analyses in the image domain using \textsc{LineStacker} on sources between $z=1$ and $z=5$, further improving the depth of our data. The large field of view provided by the ALCS allows us to reach a final sample of $\sim4000$ galaxies with known coordinates and SED-derived physical parameters. We stack sources with SFR between $10^{-3}$ and $10^{3}$ M$_\odot$ per year, and stellar mass between $10^{8}$ and $10^{12}$ M$_\odot$, splitting them in different stellar mass and SFR bins. Through stacking we retrieve the continuum 1.2\,mm flux, a known dust mass tracer, allowing us to derive the dust mass evolution with redshift and its relation with SFR and stellar mass. We observe clear continuum detections in the majority of the subsamples. From the non detections we derive 3-$\sigma$ upper limits. We observe a steady decline in the average dust mass with redshift. Moreover, sources with higher stellar mass or SFR have higher dust mass on average, allowing us to derive scaling relations. Our results are mostly in good agreement with models at $z\sim1$-3, but indicate typically lower dust-mass than predicted at higher redshift.

The radiation physics of gamma-ray bursts (GRBs) remains an open question. Based on the simulation analysis and recent observations, it was proposed that GRB jets are composed of a narrow ultra-relativistic core surrounded by a wide sub-relativistic cocoon. We show that emission from the synchrotron radiations and the synchrotron self-Compton (SSC) process of shear-accelerated electrons in the mixed jet-cocoon (MJC) region and internal-shock-accelerated electrons in the jet core is potentially explained the spectral characteristics of the prompt gamma-rays. Assuming an exponential-decay velocity profile, the shear flow in the MJC region can accelerate electrons up to $\gamma_{\rm e,\max} \sim 10^4$ for injected electrons with $\gamma_{\rm e,inject}=3 \times 10^2$, if its magnetic field strength ($B_{\rm cn}$) is $100$ G and its inner-edge velocity ($\beta_{\rm cn, 0}$) is 0.9c. The cooling of these electrons is dominated by the SSC process, and the emission flux peaks at the keV band. In addition, the energy flux of synchrotron radiations of internal-shock-accelerated electrons ($\gamma_e=10^{4}\sim 10^{5}$) peaks at around the keV$-$MeV band, assuming a bulk Lorentz factor of 300, a magnetic field strength of $\sim 10^{6}$ G for the jet core. Adding the flux from both the jet core and the MJC region, the total spectral energy distribution (SED) illustrates similar characteristics as the broadband observations of GRBs. The bimodal and Band-Cut spectra observed in GRBs 090926A, 131108A, and 160509A can be well fit with our model. The derived $B_{\rm cn}$ varies from 54 G to 450 G and $\beta_{\rm cn,0}=0. 83\sim 0.91$c.

Blue horizontal-branch (BHB) stars are crucial for studying the structure of the Galactic halo. Accurate atmospheric parameters of BHB stars are essential for investigating the formation and evolution of the Galaxy. In this work, a data-driven technique named stellar label machine (SLAM) is used to estimate the atmospheric parameters of Large Sky Area Multi-Object Fiber Spectroscopic Telescope low-resolution spectra (LAMOST-LRS) for BHB stars with a set of A-type theoretical spectra as the training dataset. We add color indexes ($(BP-G), (G-RP), (BP-RP), (J-H)$) during the training process to constrain the stellar temperature further. Finally, we derive the atmospheric parameters ($T_\mathrm{eff}$, log\, $g$, [Fe/H]) for 5,355 BHB stars. Compared to existing literature results, our results are more robust, after taking the color index into account, the resulted precisoin of $T_\mathrm{eff}$, log\, $g$ is significantly improved, especially for the spectrum with low signal-to-noise ratio (S/N). Based on the duplicate observations with a S/N difference $< 20\%$, the random errors are around 30\,K, 0.1~dex, and 0.12~dex for $T_\mathrm{eff}$, log\,$g$, [Fe/H], respectively. The stellar labels provided by SLAM are also compared to those from the high-resolution spectra in literature. The standard deviation between the predicted star labels and the published values from the high-resolution spectra is adopted as \sout{to} the statistical uncertainty of our results. They are $\sigma$($T_\mathrm{eff}$) = 76\,K, $\sigma$(log\,$g$) = 0.04~dex, and $\sigma$([Fe/H]) = 0.09~dex, respectively.

The discovery of fast moving stars in the Milky Way's most massive globular cluster, $\omega$Centauri ($\omega$Cen), has provided strong evidence for an intermediate-mass black hole (IMBH) inside of it. However, $\omega$Cen is known to be the stripped nuclear star cluster (NSC) of an ancient, now-destroyed, dwarf galaxy. The best candidate to be the original host progenitor of $\omega$Cen is the tidally disrupted dwarf $Gaia$-Sausage/Enceladus (GSE), a former Milky Way satellite as massive as the Large Magellanic Cloud. I compare $\omega$Cen/GSE with other central BH hosts and place it within the broader context of BH-galaxy (co)evolution. The IMBH of $\omega$Cen/GSE follows the scaling relation between central BH mass and host stellar mass (${\rm M}_{\rm BH}{-}{\rm M}_\star$) extrapolated from local massive galaxies (${\rm M}_\star \gtrsim 10^{10}\,{\rm M}_\odot$). Therefore, the IMBH of $\omega$Cen/GSE suggests that this relation extends to the dwarf-galaxy regime. I verify that $\omega$Cen (GSE), as well as other NSCs with candidate IMBHs and ultracompact dwarf galaxies, also follow the ${\rm M}_{\rm BH}{-}\sigma_\star$ relation with stellar velocity dispersion. Under the assumption of a direct collapse BH, $\omega$Cen/GSE's IMBH would require a low initial mass ($\lesssim$10,000 ${\rm M}_{\odot}$) and almost no accretion over $\sim$3 Gyr, which could be the extreme opposite of high-$z$ galaxies with overmassive BHs such as GN-z11. If $\omega$Cen/GSE's IMBH formed from a Population III supernova remnant, then it could indicate that both light and heavy seeding mechanisms of central BH formation are at play. Other stripped NSCs and dwarf galaxies could help further populate the ${\rm M}_{\rm BH}{-}{\rm M}_{\star}$ and ${\rm M}_{\rm BH}{-}\sigma_\star$ relations in the low-mass regime and constraint IMBH demographics and their formation channels.

In Radio Super Novae (RSNe) a magnetic field of $(B \, \times \, r) \, = \, 10^{16.0 \pm 0.12} \, {\rm Gauss \, \times \, cm}$ is observed; these are the same numbers for Blue Super Giant (BSG) star explosions as for Red Super Giant (RSG) star explosions, despite their very different wind properties. The EHT data for M87 as well for low power radio galaxies all show consistency with just this value of the quantity $(B \, \times \, r )$, key for angular momentum and energy transport, and can be derived from the radio jet data. We interpret this as a property of the near surroundings of a black hole (BH) at near maximal rotation, independent of BH mass. In the commonly used green onion model, in which a $2 \, \pi$ flow changes over to a jet flow we interpret this as a wind emanating from the BH/accretion disk system and its surroundings. Near the BH collisions in the wind can produce a large fraction of anti-protons. In this scenario the cosmic Ray (CR) population from the wind/jet is proposed to be visible as EeV protons and anti-protons in the CR data to EeV energy, with a $E^{-7/3}$ spectrum. This can be connected to a concept of inner and outer Penrose zones in the ergo-region. The observed numbers for the magnetic field imply the Planck time as the governing time scale: A BH rotating near maximum can accept a proton per log bin of energy in an extended spectrum with the associated pions every Planck time.

We present the solution approach developed by the team `TheAntipodes' during the 12th edition of the Global Trajectory Optimization Competition (GTOC 12). An overview of the approach is as follows: (1) generate asteroid subsets, (2) chain building with beam search, (3) convex low-thrust trajectory optimization, (4) manual refinement of rendezvous times, and (5) optimal solution set selection. The generation of asteroid subsets involves a heuristic process to find sets of asteroids that are likely to permit high-scoring asteroid chains. Asteroid sequences `chains' are built within each subset through a beam search based on Lambert transfers. Low-thrust trajectory optimization involves the use of sequential convex programming (SCP), where a specialized formulation finds the mass-optimal control for each ship's trajectory within seconds. Once a feasible trajectory has been found, the rendezvous times are manually refined with the aid of the control profile from the optimal solution. Each ship's individual solution is then placed into a pool where the feasible set that maximizes the final score is extracted using a genetic algorithm. Our final submitted solution placed fifth with a score of $15,489$.

In the study of cosmology and galaxy evolution, the peculiar velocity and density field of dark matter (DM) play a crucial role in studying many issues. Here, we propose a UNet-based deep learning to reconstruct the real-space DM velocity field from the spatial distribution of a sparse sample of DM halos in redshift space. By comparing and testing various properties, we demonstrate that the reconstructed velocity field is in good agreement with the actual situation. At $k<0.3~h/{\rm Mpc}$, the reconstruction of various velocity field components, including velocity magnitude and divergence, outperforms traditional linear perturbation theory. Additionally, the effects of redshift space distortions (RSD) are well corrected using the UNet model. Compared to the true real-space power spectra, the UNet reconstruction provides an unbiased estimate of the density, velocity, and momentum fields, remaining consistent within $2\sigma$ level. We also demonstrate that the UNet model remains effective even with limited information about halo masses. Thus, our proposed UNet model has a wide range of applications in various aspects of cosmology, such as RSD, cosmic web analysis, the kinetic Sunyaev-Zel'dovich effect, BAO reconstruction, and so on.

The optimal design of multi-target rendezvous and flyby missions presents significant challenges due to their inherent combination of traditional spacecraft trajectory optimization with high-dimensional combinatorial problems. This often necessitates the use of large-scale global search techniques, which are computationally expensive, or the use of simplified approximations that may yield suboptimal results. To address these issues, a nested-loop approach is proposed, where the problem is divided into separate combinatorial and optimal control problems. The combinatorial problem is formulated and solved using Binary Integer Programming (BIP) with a fixed rendezvous time schedule, whilst the optimal control problem is handled by adaptive-mesh Sequential Convex Programming (SCP), which additionally optimizes the time schedule. By iterating these processes in a nested-loop structure, the approach can efficiently find high-quality solutions. This method is applied to the Global Trajectory Optimization Competition 12 (GTOC 12) problem, leading to the creation of several new best-known solutions.

In the present paper, we analyze three energetic X-ray flares from the active RS CVn binary HR 1099 using data obtained from XMM-Newton. The flare duration ranges from 2.8 to 4.1 h, with e-folding rise and decay times in the range of 27 to 38 minutes and 1.3 to 2.4 h, respectively, indicating rapid rise and slower decay phases. The flare frequency for HR 1099 is one flare per rotation period. Time-resolved spectroscopy reveals peak flare temperatures of 39.44, 35.96, and 32.48 MK, emission measures of $7 \times 10^{53}$ to $8 \times 10^{54}$ cm$^{-3}$, global abundances of 0.250, 0.299, and 0.362 $Z_\odot$, and peak X-ray luminosities of $ 10^{31.21-32.29}$ erg s$^{-1}$. The quiescent state is modeled with a three-temperature plasma maintained at 3.02, 6.96, and 12.53 MK. Elemental abundances during quiescent and flaring states exhibit the inverse-FIP effect. We have conducted a comparative analysis of coronal abundances with previous studies and found evidence supporting the i-FIP effect. The derived flare semi-loop lengths of 6 to 8.9 $\times 10^{10}$ cm were found to be comparable to the other flares detected on HR 1099; however, they are significantly larger than typical solar flare loops. The estimated flare energies, ranging from $10^{35.83-37.03}$ erg, classify these flares as super-flares. The magnetic field strengths of the loops are found to be in the range of 350 to 450 G. We diagnose the physical conditions of the flaring corona in HR 1099 through the observations of superflares and provide inference on the plasma processes.

The geometry of the Comptonization corona in neutron star low-mass X-ray binaries is still unclear. We conducted time-resolved polarimetric analysis of the archival observations of XTE J1701--462 obtained with the \textit{Imaging X-ray Polarimeter Explorer} during its 2022 outburst, and found that the polarization angle (PA) varied significantly with time when the source was in the normal branch (NB), with $67 \pm 8^{\circ}$ in the first epoch, $-34 \pm 8^{\circ}$ in the second, and $-58 \pm 8^{\circ}$ in the third, last epoch. Meanwhile, the polarization degree remained constant at around 2\%, above the minimum detectable polarization at the 99\% confidence level (MDP$_{99}$). The rapid PA variation causes depolarization in the time-averaged data, resulting in a nondetection as reported in the literature. The rapid (intra-day) PA variation may suggest that there is a fast transformation of the corona geometry, likely switching from a slab geometry to a more vertically extended spreading layer geometry, along with enhanced disk emission and reflection.

The origin of jet launching mainly comes from two mechanisms: the BZ mechanism and the BP mechanism. However, it is in debate which one is dominating in blazars. In this work, we used a sample of 937 Fermi blazars to study the jet formation mechanism. We studied the correlation between the jet power and the accretion rate, as well as the comparison between jet power estimated by spectral energy distribution (SED) fitting and that estimated by theoretical formula and radio flux density. Our results suggest that there is no correlation between jet power estimated by SED fitting and the accretion rate for BL Lacs, while a positive and weak correlation exists for flat spectrum radio quasars (FSRQs). Meanwhile, to confirm whether the BP and BZ mechanism is sufficient to launch the jet for FSRQs and BL Lacs, we compare the theoretical jet power with that estimated by SED fitting, as well as that by radio emission. We found that the jet power for most of the two subclasses estimated by SED fitting cannot be explained by either the BP or BZ mechanism. While the jet power for most FSRQs estimated by radio flux density can be explained by the BP mechanism, and most BL Lacs can be explained by the BZ mechanism. We also found that FSRQs have higher accretion rates than BL Lacs, implying different accretion disks around their central black holes: FSRQs typically have standard disks, while BL Lacs usually have advection-dominated accretion flow disks.

The formation sequence of bulges and disks in late-type galaxies (LTGs) remains a subject of debate. Some studies propose that the bulge is present early in galaxy formation, with the disk forming later, while others suggest the disk forms first, followed by bulge development. This ongoing discussion highlights the necessity for additional observational and simulation-based investigations to enhance our understanding. In this study, utilizing a bulge+disk decomposition catalog for a large LTG sample, we examine, for the first time, the alignment between the major axes of central bulge components and their host large-scale filaments. Our analysis indicates no significant alignment signal for the bulge components. However, we observe alignment between the major axes of central bulges and outer disks in the sky plane, suggesting that the formation of central bulges in LTGs may be influenced by, or even driven by, the migration of components from the outer disks. Our results offer a novel perspective on bulge formation mechanisms from an alignment standpoint, providing unique insights for related research endeavors.

Recently, the Large High-Altitude Air Shower Observatory (LHAASO) collaboration has obtained a measurement of the gamma-ray diffuse emission in the ultra-high energy range, $10-10^3$ TeV after masking the contribution of known sources. The measurement appears to be 2-3 times higher than the gamma-ray signal expected from the hadronic interactions of diffuse cosmic rays with the interstellar medium, potentially suggesting a contribution from unresolved sources. However, estimates of the diffuse emission are affected by large uncertainties that must be accounted for. In this work, we calculate the hadronic gamma-ray diffuse emission including uncertainties in the gas content of the Galactic disk, in the energy and spatial distribution of cosmic rays as well as in the hadronic interaction cross-section. We show that the LHAASO data above $\sim 30$ TeV are consistent with the gamma-ray diffuse emission model when all these uncertainties are taken into account. This implies that, with the current data in this energy range, there is no need to invoke a cosmic ray spectral variation toward the Galactic center, nor a dominant contribution from unresolved sources.

E to B mixing or "leakage" due to time-ordered data (TOD) filtering has become an important source of sensitivity loss that ground-based cosmic microwave background polarization experiments must address. However, it is a difficult problem for which very few viable solutions exist. In this paper, we expand upon satellite E-mode methods to cover E/B leakage specifically due to TOD filtering. We take a satellite E-mode map and TOD filter it through the ground-based experiment data analysis pipeline, from which we construct a map-space "leakage template" and subtract it from the ground-based experiment map. We evaluate the residual leakage by simulating the satellite E-mode maps with Planck-like and LiteBIRD-like noise levels, and simulate the ground-based experiment with Simons Observatory-like and CMB-S4-like noise levels. The effectiveness of the method is measured in the improvement of the Fisher uncertainty $\sigma(r=0)$. We find that our method can reduce $\sigma(r=0)$ by $\sim15\text{--}75\%$ depending on the noise levels considered.

We employ a semi-analytical methodology to estimate the dark matter halo spin of HI gas-rich galaxies in the Arecibo Legacy Fast Alfa Survey and investigate the relationship between halo spin and the proximity of galaxies to large-scale filaments. We exclude galaxies with low HI signal-to-noise ratios, those potentially influenced by velocity dispersions, and those affiliated with galaxy clusters/groups. Additionally, we apply a mass-weighting technique to ensure consistent mass distribution across galaxy samples at varying distances from filaments. Our analysis reveals, for the first time, a subtle yet statistically significant correlation between halo spin and filament distance in observational data, indicating higher spins closer to filaments. This suggests that the tidal forces exerted by filaments may impact the spin of dark matter halos.

Using a semi-analytic approach, we estimate halo spins for a large sample of HI-rich galaxies from the Arecibo Legacy Fast Alfa Survey and examine the correlation between HI mass fractions and halo spins. Our analysis reveals a strong correlation between halo spin and the HI-to-stellar mass ratio in both low-mass and massive galaxy samples. This finding suggests a universal formation scenario: higher halo spin reduces angular momentum loss and gas condensation, leading to lower star formation rates and weaker feedback, which in turn helps retain gas within dark matter halos.

Migration is a key ingredient for the formation of close-in super-Earth and mini-Neptune systems, as it sets in which resonances planets can be trapped. Slower migration rates result in wider resonance configurations compared to higher migration rates. We investigate the influence of different migration rates, set by the disc's viscosity, on the structure of multi-planet systems growing by pebble accretion via N-body simulations. Planets in low viscosity environments migrate slower due to partial gap opening. Thus systems formed in low viscosity environments tend to have planets trapped in wider resonant configurations (typically 4:3, 3:2 and 2:1), compared to their high viscosity counterparts (mostly 7:6, 5:4 and 4:3 resonances). After gas disc dissipation, the damping forces cease and the systems can undergo instabilities, rearranging their configurations and breaking the resonance chains. The low viscosity discs naturally account for the resonant chains like Trappist-1, TOI-178 and Kepler-223, unlike high viscosity simulations which produce relatively more compact chains. About 95% of our low viscosity resonant chains became unstable, experiencing giant impacts. Dynamical instabilities in our low viscosity simulations are more violent than those of high viscosity simulations due to the effects of leftover external perturbers (P>200 days). About 50% of our final system ended with no planets within 200 days, while all our systems have remaining outer planets. We speculate that this process could be qualitatively consistent with the lack of inner planets in a large fraction of Sun-like stars. Systems produced in low viscosity simulations alone do not match the overall period ratio distribution of observations, but give a better match to the period distributions of chains, which may suggest that systems of super-Earths and mini-Neptunes form in natal discs with a diversity of viscosities.

Compact hierarchical triples (CHTs) are triple stars where the tertiary is in an orbit of a period less than 1000 d. They were thought to be rare but we are discovering more of these systems recently, thanks to space-based missions like TESS, Kepler, and GAIA. In this work, we use orbital parameters obtained from these missions to constrain the formation process of CHTs. We also use spectroscopic and systemic parameters from our work, and the literature to understand the effects of metallicity and dynamics on the formation processes.

The rest wavelengths of DIBs are of fundamental importance owing to the lack of unambiguous identification for these mysterious features. Usually the wavelengths of DIBs are estimated using known interstellar lines serving to shift the spectrum to the rest wavelengths velocity scale. However, the latter may not share in fact the same parts of a cloud which carriers of DIBs occupy. Here we argue that the narrowest known DIB 6196 A is the best reference feature. Also, we offer the geometrical center of gravity (the effective wavelength) of diffuse bands as a rest wavelength measurer for these generally asymmetric features. The exception is DIB 6196: its symmetrical (bottom) part must be used as a reference for the interstellar wavelength scale, and its center of gravity serves to study the variability of the feature visible at the upper part of its profile. We assessed the magnitude of variation of the center of gravity of DIBs at 5780, 5797, 6284 and 7224 A measured in 41 objects in the range of E{B-V} between 0.13 and 1.06 mag. with the lack of Doppler-split in profiles of interstellar atomic/molecular lines. To estimate the width of diffuse bands we offer to apply a parameter "effective width" W_eff which is the relation of the equivalent width to the depth of the feature. In contrast to habitual FWHM, W_eff is not sensitive to the profile shape irregularities. W_eff provides lower uncertainties of the measurements than the FWHM does. The gradual increase of W_eff, accompanied with the red-shift of the center of gravity of the profile, may suggest populating of higher transitions of P-branch of the bands of molecules, assuming the latter are DIB carriers. It is also shown, that diffuse bands are broader although more shallow in the harsh conditions of sigma-clouds. The difference of the effective width of DIBs in zeta and sigma clouds is discussed as well.

There are more than 60 broad-line Ic (Ic-BL) supernovae (SNe) which are associated with a long Gamma-ray Burst (GRB). A large population of `ordinary' Ic-BLs for which no GRB component is detected also exists. On average, the expansion velocities of GRB-associated Ic-BLs exceed those of ordinary Ic-BLs. This work presents the largest spectroscopic sample of Ic-BL SNe with and without GRBs to date. The goal of this work is to investigate how the expansion velocities evolve in cases where an ultra-relativistic jet has been launched (GRB-SN cases) and compare these to Ic-BL SNe without a GRB detection. We measured the expansion velocities of the Fe II, Si II and Ca II lines observed in the spectra of Ic-BL SNe using a spline fitting method. We fit the expansion velocity evolution with single and broken power-laws. The expansion velocities of the Fe II and Si II features reveal considerable overlap between the two populations. It is not clear that GRB-associated supernovae expand more rapidly. Broken power-law evolution appears to be more common for the Si II feature, which always follows a shallow-steep decay, while the broken power-law Fe II decays are predominantly steep-shallow. The power-law indices for both samples were compared for both Fe II and Si II, and suggest that GRB-SNe decline at a similar rate to non-GRB Ic-BL supernovae. Neither the velocities nor their evolution can be used to distinguish between Ic-BLs with and without GRBs. Expansion velocities consistent with broken power-law evolution may indicate the presence of two velocity components, which may be evidence for a jet in some of these explosions. However, it is not possible to rule in or out the presence of a jet in any Ic-BL supernova purely based on the velocities. These results suggest that GRB-SNe and Ic-BLs are drawn from the same underlying population of events.

In this study, we perform detailed spectroscopic modeling to analyze the interaction of circumstellar material (CSM) with ejecta in both hydrogen-rich and hydrogen-poor superluminous supernovae (SLSNe), systematically varying properties such as CSM density, composition, and geometry to explore their effects on spectral lines and light curve evolution. Using advanced radiative transfer simulations with the new, open-source SuperLite code to generate synthetic spectra, we identify key spectroscopic indicators of CSM characteristics. Our findings demonstrate that spectral lines of hydrogen and helium exhibit significant variations due to differences in CSM mass and composition. In hydrogen-rich SLSN- II, we observe pronounced hydrogen emission lines that correlate strongly with dense, extended CSM, suggesting massive, eruptive mass-loss histories. Conversely, in hydrogen-poor SLSNe, we recover mostly featureless spectra at early times, with weak hydrogen lines appearing only in the very early phases of the explosion, highlighting the quick ionization of traces of hydrogen present in the CSM. We analyze the properties of the resulting emission lines, particularly $\rm H_{\alpha}$ and $\rm H_{\beta}$, for our models using sophisticated statistical methods. This analysis reveals how variations in the supernova progenitor and CSM properties can lead to distinct spectroscopic evolutions over time. These temporal changes provide crucial insights into the underlying physics driving the explosion and the subsequent interaction with the CSM. By linking these spectroscopic observations to the initial properties of the progenitor and its surrounding ma

Motivated by the difference between the fluxes of sub-PeV Galactic diffuse gamma-ray emission (GDE) measured by the Tibet AS$\gamma$ experiment and the LHAASO collaboration, our study constrains the contribution to the GDE flux measured by Tibet AS$\gamma$ from the sub-PeV gamma-ray sources in the first LHAASO catalog plus the Cygnus Cocoon. After removing the gamma-ray emission of the sources masked in the observation by Tibet AS$\gamma$, the contribution of the sources to the Tibet diffuse flux is found to be subdominant; in the sky region of $25^{\circ} < l < 100^{\circ}$ and $|b| < 5^{\circ}$, it is less than 26.9% $\pm$ 9.9%, 34.8% $\pm$ 14.0%, and ${13.5%}^{+6.3%}_{-7.7%}$ at 121 TeV, 220 TeV, and 534 TeV, respectively. In the sky region of $50^{\circ} < l < 200^{\circ}$ and $|b| < 5^{\circ}$, the fraction is less than 24.1% $\pm$ 9.5%, 27.1% $\pm$ 11.1% and ${13.5%}^{+6.2%}_{-7.6%}$. After subtracting the source contribution, the hadronic diffusive nature of the Tibet diffuse flux is the most natural interpretation, although some contributions from very faint unresolved hadronic gamma-ray sources cannot be ruled out. Different source-masking schemes adopted by Tibet AS$\gamma$ and LHAASO for their diffuse analyses result in different effective galactic latitudinal ranges of the sky regions observed by the two experiments. Our study concludes that the effect of the different source-masking schemes leads to the observed difference between the Tibet diffuse flux measured in $25^{\circ} < l < 100^{\circ}$ and $|b| < 5^{\circ}$ and LHAASO diffuse flux in $15^{\circ} < l < 125^{\circ}$ and $|b| < 5^{\circ}$.

Condensation processes, which are responsible for the main chemical differences between gas and solids in the Galaxy, are the major mechanisms that control the cycle of dust from evolved stars to planetary systems. However, they are still poorly understood, mainly because the thermodynamics and kinetic models of nucleation or grain growth lack experimental data. To bridge this gap, we used a large-volume three-phase alternating-current plasma torch to obtain a full high-temperature condensation sequence at an elevated carbon-to-oxygen ratio from a fluxed chondritic gas composition. We show that the crystallized suites of carbides, silicides, nitrides, sulfides, oxides and silicates and the bulk composition of the condensates are properly modelled by a kinetically inhibited condensation scenario controlled by gas flow. This validates the thermodynamic predictions of the condensation sequence at a high carbon-to-oxygen ratio. On this basis and using appropriate optical properties, we also demonstrate the influence of pressure on dust chemistry as well as the low probability of forming and detecting iron silicides in asymptotic giant branch C-rich circumstellar environments as well as in our chondritic meteorites. By demonstrating the potential of predicting dust mineralogy in these environments, this approach holds high promise for quantitatively characterizing dust composition and formation in diverse astrophysical settings.

The James Webb Space Telescope has uncovered a puzzling population of UV-faint broad-line active galactic nuclei (AGN), nicknamed ``Little Red Dots'' (LRD) owing to their compact morphology and red rest-frame optical colours. Interpreted as dust attenuated AGN, their inferred intrinsic luminosities and supermassive black hole (SMBH) masses rival those of UV-luminous quasars, although they are $>100$ times more abundant. If LRDs and quasars are members of the same underlying population, they should inhabit comparable mass dark matter halos, traced by similar overdensities of galaxies. Otherwise, they represent distinct populations with different physical properties and formation histories. Characterizing LRD environments thus provides a critical test of their nature. Here, we report the discovery of a LRD at $z=7.3$, attenuated by moderate amounts of dust, $A_V = {3.26}\,\rm{mag}$, with an intrinsic bolometric luminosity of $10^{46.7}\,\rm{erg}\,\rm{s}^{-1}$ and a SMBH mass of $7\times10^8\,\rm{M}_\odot$. Most notably, this object is embedded in an overdensity of eight nearby galaxies, allowing us to calculate the first spectroscopic estimate of the clustering of galaxies around LRDs. We find a LRD-galaxy cross-correlation length of $r_0\!=\!9\pm2\,\rm{h}^{-1}\,\rm{cMpc}$, comparable to that of $z\!\sim\!6$ UV-luminous quasars. The resulting estimate of their minimum dark matter halo mass of $\log_{10}(M_{\rm{halo, min}}/\rm{M}_{\odot})= 12.3_{-0.8}^{+0.7}$ indicates that nearly all halos above this mass must host actively accreting SMBHs at $z\approx7$, in strong contrast with the far smaller duty cycle of luminous quasars ($<1\%$). Our results, taken at face value, motivate a picture in which LRDs are the obscured counterparts of UV-luminous quasars, which provides a natural explanation for the short UV-luminous lifetimes inferred from both quasar clustering and quasar proximity zones.

This paper presents the design and development of a Shear and Compression Cell (SCC) for measuring the mechanical properties of granular materials in low-gravity environments. This research is motivated by the increasing interest in planetary exploration missions that involve surface interactions, such as those to asteroids and moons. The SCC is designed to measure key mechanical properties, including Young's modulus, angle of internal friction, bulk cohesion, and tensile strength, under both reduced gravity and microgravity conditions. By utilizing a drop tower with interchangeable configurations, we can simulate the gravitational environments of celestial bodies like the Moon and Titan. The SCC, coupled with the drop tower, provides a valuable tool for understanding the behavior of regolith materials and their implications for future space exploration missions.

Hydrogen cyanide delivered by cometary impactors can be concentrated as ferrocyanide salts, which may support the initial stages of prebiotic chemistry on the early Earth. One way to achieve the conditions required for a variety of prebiotic scenarios, requiring for example the formation of cyanamide and cyanoacetylene, is through the arrival of a secondary impactor. In this work, we consider the bombardment of the early Earth, and quantitatively evaluate the likelihood of origins scenarios that invoke double impacts. Such scenarios are found to be possible only at very early times ($>\,$4Gya), and are extremely unlikely settings for the initial stages of prebiotic chemistry, unless (i) ferrocyanide salts are stable on 1000yr timescales in crater environments, (ii) there was a particularly high impact rate on the Hadean Earth, and (iii) environmental conditions on the Hadean Earth were conducive to successful cometary delivery (i.e., limited oceanic coverage, and low ($\lesssim 1$bar) atmospheric surface pressure). Whilst environmental conditions on the early Earth remain subject to debate, this work highlights the need to measure the typical lifetime of ferrocyanide salts in geochemically realistic environments, which will determine the plausibility of double impact scenarios.

The observed star formation rates of galaxies in the Local Universe suggests that they are replenishing their gas reservoir across cosmic time. Cosmological simulations predict that this accretion of fresh gas can occur in a hot or a cold mode, yet the existence of low column density ($\sim10^{17}$ cm$^{-2}$) neutral atomic hydrogen (HI) tracing the cold mode has not been unambiguously confirmed by observations. We present the application of unconstrained spectral stacking to attempt to detect the emission from this HI in the Circum-Galactic Medium (CGM) and Inter-Galactic Medium (IGM) of 6 nearby star forming galaxies from the MHONGOOSE sample for which full-depth observations are available. Our stacking procedure consists of a standard spectral stacking algorithm coupled with a one-dimensional spectral line finder designed to extract reliable signal close to the noise level. In agreement with previous studies, we found that the amount of signal detected outside the HI disk is much smaller than implied by simulations. Furthermore, the column density limit that we achieve via stacking ($\sim10^{17}$ cm$^{-2}$) suggests that direct detection of the neutral CGM/IGM component might be challenging in the future, even with the next generation of radio telescopes.

Coronal mass ejections (CMEs) can exhibit non-radial evolution. The background magnetic field is considered the main driver for the trajectory deviation relative to the source region. The influence of the magnetic environment has been largely attributed to the gradient of the magnetic pressure. In this work, we propose a new approach to investigate the role of topology on CME deflection and to quantify and compare the action between the magnetic field gradient (`gradient' path) and the topology (`topological' path). We investigate 8 events simultaneously observed from Solar Orbiter, STEREO-A and SDO; and, with a new tracking technique, we reconstruct the 3D evolution of the eruptions. Then, we compare their propagation with the predictions from the two magnetic drivers. We find that the `topological' path describes the CME actual trajectory much better than the more traditional `gradient path'. Our results strongly indicate that the ambient topology may be the dominant driver for deflections in the low corona, and that presents a promising method to estimate the direction of propagation of CMEs early in their evolution.

The double detonation is a widely discussed explosion mechanism for Type Ia supernovae, whereby a helium shell detonation ignites a secondary detonation in the carbon/oxygen core of a white dwarf. Even for modern models that invoke relatively small He shell masses, many previous studies have found that the products of the helium shell detonation lead to discrepancies with normal Type Ia supernovae, such as strong Ti II absorption features, extremely red light curves and too large a variation with viewing direction. It has been suggested that non local thermodynamic equilibrium (non-LTE) effects may help to reduce these discrepancies with observations. Here we carry out full non-LTE radiative transfer simulations for a recent double detonation model with a relatively small helium shell mass of 0.05 M$_\odot$. We construct 1D models representative of directions in a 3D explosion model to give an indication of viewing angle dependence. The full non-LTE treatment leads to improved agreement between the models and observations. The light curves become less red, due to reduced absorption by the helium shell detonation products, since these species are more highly ionised. Additionally, the expected variation with observer direction is reduced. The full non-LTE treatment shows promising improvements, and reduces the discrepancies between the double detonation models and observations of normal Type Ia supernovae.

The variation of the physical conditions across the three dimensions of our Galaxy is a major source of complexity for the modelling of the foreground signal facing the cosmic microwave background (CMB). In the present work, we demonstrate that the spin-moment expansion formalism provides a powerful framework to model and understand this complexity, with a special focus on that arising from variations of the physical conditions along each line-of-sight on the sky. We perform the first application of the moment expansion to reproduce a thermal dust model largely used by the CMB community, demonstrating its power as a minimal tool to compress, understand and model the information contained within any foreground model. Furthermore, we use this framework to produce new models of thermal dust emission containing the maximal amount of complexity allowed by the current data, remaining compatible with the observed angular power-spectra by the $Planck$ mission. By assessing the impact of these models on the performance of component separation methodologies, we conclude that the additional complexity contained within the third dimension could represent a significant challenge for future CMB experiments and that different component separation approaches are sensitive to different properties of the moments.

By employing ray-tracing techniques, we investigate the shadow images of rotating Bardeen black holes surrounded by perfect fluid dark matter. In this work, two models are considered for the background light source, namely the celestial light source model and the thin accretion disk model. Regarding the celestial light source, the investigation focuses on the impact of variations in relevant parameters and observed inclination on the contour and size of the shadow. For the thin accretion disk model, the optical appearance of a black hole is evidently contingent upon the radiative properties exhibited by the accretion disk, as well as factors such as observed inclination and relevant parameters governing spacetime. With an increasing observation inclination, the observed flux of direct and lensed images of the accretion disk gradually converge towards the lower region of the image, while an increase in the dark matter parameter $a$ significantly expands the region encompassing both direct and lensed images. Furthermore, the predominant effect is redshift at lower observation angles, whereas the blueshift effect only becomes apparent at higher observation angles. Simultaneously, the increase in the observation inclination will amplify the redshift effect, whereas an increase in the magnetic charge $\mathcal{G}$, rotation parameter $a$ and the absolute value of dark matter parameter $\alpha$ will attenuate the redshift effect observed in the image. These observations of a rotating Bardeen black hole surrounded by perfect fluid dark matter could provide a convenient way to distinguish it from other black hole models.

We critically review the evidence for time-varying dark energy from recent Baryon Acoustic Oscillations (BAO) and Supernova (SN) observations. First, we show that such evidence is present at the 3$\sigma$ level, even without the new BAO data from the dark energy Spectroscopic Instrument (DESI), by instead using BAO data from the dark energy Survey (DES), combined with the DES5Y supernovae and Planck CMB data. Next, we examine the role of the DES5Y supernova dataset, showing that the preference for time-varying dark energy is driven by the low redshift supernovae common to both the DES5Y and Pantheon+ compilations. We find that combining Pantheon+ and DES5Y supernovae by removing the common supernovae leads to two different results, depending on whether they are removed from the DES5Y or the Pantheon+ catalog, leading to stronger or weaker exclusion of $\Lambda$CDM, at the (3.8$\sigma$) and (2.5$\sigma$) level, respectively. These common supernovae have smaller error bars in DES5Y compared to Pantheon+, and, as recently pointed out, there is an offset in magnitude in DES5Y between supernovae at ($z > 0.1$), where almost all the measurements taken during the full five years of DES are, and the low-redshift ones ($z < 0.1$), where all the historical set of nearby supernovae lies. We show that marginalizing over such an offset in DES5Y would lead to significantly weaker evidence for evolving dark energy.

Astrophysical outflows are ubiquitous across cosmic scales, from stellar to galactic systems. While diverse launching mechanisms have been proposed, we demonstrate that these outflows share a fundamental commonality: their morphology follows the physics of pressure-confined supersonic flows. By extending classical deLaval nozzle theory to account for ambient pressure gradients, we present a unified framework that successfully describes outflows from young stellar objects to active galactic nuclei. Our model reveals a remarkable consistency in pressure profiles, characterized by a power-law exponent near minus two, independent of the internal characteristics of the outflow or the nature of central engine. This discovery suggests a universal mechanism for outflow collimation and acceleration, bridging the gap between theoretical models and observational features across a wide range of astronomical scales.

Growing planets interact with their surrounding protoplanetary disk, generating feedback effects that may promote or suppress nearby planet formation. We study how spiral waves launched by planets affect the motion and collisional evolution of particles in the disk. To this end, we perform local 2D hydrodynamical simulations that include a gap-opening planet and integrate particle trajectories within the gas field. Our results show that particle trajectories bend at the location of the spiral wave, and collisions occurring within the spiral exhibit significantly enhanced collisional velocities compared to elsewhere. To quantify this effect, we ran simulations with varying planetary masses and particle sizes. The resulting collisional velocities within the spiral far exceed the typical fragmentation threshold, even for collisions between particles of relatively similar sizes and for planetary masses below the pebble isolation mass. If collisions within the spiral are frequent, this effect could lead to progressively smaller particle sizes as the radial distance from the planet decreases, impacting processes such as gap filtering, pebble accretion, and planetesimal formation.

It is found that a non-minimally coupled scalar tensor theory, Thawing Gravity (TG), can explain multiple tensions plaguing the standard cosmological model $\Lambda$CDM while fitting better to observations than the latter. Using the standard Bayes model comparison method, TG has moderate evidence over $\Lambda$CDM with a Bayes factor $\ln B=+1.5$ in the baseline analysis including CMB, BAO and SNIa. In the baseline+$H_0$ analysis which further takes into account the Cepheids calibration of the SNIa distance ladder from SH0ES, TG has very strong evidence over $\Lambda$CDM with $\ln B=+11.8$. In particular, TG yields $H_0=71.78\pm0.86 \ {\rm km/s/Mpc}$ and $S_8=0.793\pm0.012$, consistent with both local $H_0$ measurement and the large scale structure surveys.

The detection of various molecular species, including complex organic molecules relevant to biochemical and geochemical processes, in astronomical settings such as the interstellar medium or the outer Solar System has led to the increased need for a better understanding of the chemistry occurring in these cold regions of space. In this context, the chemistry of ices prepared and processed at cryogenic temperatures has proven to be of particular interest due to the fact that many interstellar molecules are believed to originate within the icy mantles adsorbed on nano- and micro-scale dust particles. The chemistry leading to the formation of such molecules may be initiated by ionising radiation in the form of galactic cosmic rays or stellar winds, and thus there has been an increased interest in commissioning experimental set-ups capable of simulating and better characterising this solid-phase radiation astrochemistry. In this article, we describe a new facility called AQUILA (Atomki-Queen's University Ice Laboratory for Astrochemistry) which has been purposefully designed to study the chemical evolution of ices analogous to those that may be found in the dense interstellar medium or the outer Solar System as a result of their exposure to keV ion beams. The results of some ion irradiation studies of CH3OH ice at 20 K are discussed to exemplify the experimental capabilities of the AQUILA as well as to highlight its complementary nature to another laboratory astrochemistry set-up at our institute.

This work aims to spectroscopically characterize and provide for the first time direct experimental frequencies of the ground vibrational state and two excited states of the simplest alkynyl thiocyanate (HCCSCN) for astrophysical use. Both microwave (8-16~GHz) and millimeter wave regions (50-120~GHz) of the spectrum have been measured and analyzed in terms of Watson's semirigid rotor Hamiltonian. A total of 314 transitions were assigned to the ground state of HCCSCN and a first set of spectroscopic constants have been accurately determined. Spectral features of the molecule were then searched for in Sgr B2(N), NGC 6334I, G+0.693-0.027 and TMC-1 molecular clouds. Upper limits to the column density are provided.

This study investigates the astronomical implications of the Ghosh-Kumar rotating Black Hole (BH), particularly its behaviour on shadow images, illuminated by celestial light sources and equatorial thin accretion disks. Our research delineates a crucial correlation between dynamics of the shadow images and the parameters $a$,~ $q$ and the $\theta_{obs}$, which aptly reflect the influence of the model parameters on the optical features of shadow images. Initially, elevated behavior of both $a$ and $q$ transforms the geometry of the shadow images from perfect circles to an oval shape and converges them towards the centre of the screen. By imposing the backward ray-tracing method, we demonstrate the optical appearance of shadow images of the considering BH spacetime in the celestial light source. The results demonstrate that the Einstein ring shows a transition from an axisymmetric closed circle to an arc-like shape on the screen as well as producing the deformation on the shadow shape with the modifications of spacetime parameters at the fixed observational position. Next, we observe that the attributes of accretion disks along with the relevant parameters on the shadow images are illuminated by both prograde and retrograde accreting flow. Our study reveals the process by which the accretion disk transitions from a disk-like structure to a hat-like shape with the aid of observational angles. Moreover, with an increase of $q$, the observed flux of both direct and lensed images of the accretion disk gradually moves towards the lower zone of the screen. Furthermore, we present the intensity distribution of the redshift factors on the screen. Our analysis suggests that the observer can see both redshift and blueshift factors on the screen at higher observational angles, while augmenting the values of both $a$ and $q$, enhancing the effect of redshift on the screen.

This paper introduces an innovative approach to radio astronomy by utilizing the global network of Internet of Things (IoT) devices to form a distributed radio telescope. Leveraging existing IoT infrastructure with minimal modifications, the proposed system employs widely dispersed devices to simultaneously capture both astronomical and communication signals. Digital beamforming techniques are applied to align the astronomical signals, effectively minimizing interference from communication sources. Calibration is achieved using multiple distributed satellites transmitting known signals, enabling precise channel estimation and phase correction via GPS localization. We analyze two calibration methods, Phase Alignment Calibration (PAC) and Eigenvalue-Based Calibration (EVC), and demonstrate that EVC outperforms PAC in environments with significant variation in node performance. Compared to the Green Bank Telescope (GBT), the IoT-based telescope enhances antenna gain by three orders of magnitude and increases survey speed by eight orders of magnitude, owing to the vast number of nodes and expansive field of view (FoV). These findings demonstrate the feasibility and significant advantages of the IoT-enabled telescope, paving the way for cost-effective, high-speed, and widely accessible astronomical observations.

We investigated the temporal and spectral features of $\gamma$ Cassiopeiae's X-ray emission within the context of the white dwarf accretion hypothesis. We find that the variabilities present in the X-ray data show two different signals, one primarily due to absorption and the other due to flickering like in non-magnetic cataclysmic variables. We then use this two-component insight to investigate previously un-reported simultaneous XMM and NuSTAR data. The model fitting results find white dwarf properties consistent with optical studies alongside a significant secondary, thermal source. We propose a secondary shock between the Be decretion disk and white dwarf accretion disk as the source. Finally, we analyzed a unique, low-count rate event of the XMM light curve as potential evidence for the white dwarf encountering Be decretion disk structures.

The Dark Energy Spectroscopic Instrument (DESI) survey is mapping the large-scale distribution of millions of Emission Line Galaxies (ELGs) over vast cosmic volumes to measure the growth history of the Universe. However, compared to Luminous Red Galaxies (LRGs), very little is known about the connection of ELGs with the underlying matter field. In this paper, we employ a novel theoretical model, SHAMe-SF, to infer the connection between ELGs and their host dark matter subhaloes. SHAMe-SF is a version of subhalo abundance matching that incorporates prescriptions for multiple processes, including star formation, tidal stripping, environmental correlations, and quenching. We analyse the public measurements of the projected and redshift-space ELGs correlation functions at $z=1.0$ and $z=1.3$ from DESI One Percent data release, which we fit over a broad range of scales $r \in [0.1, 30]/h^{-1}$Mpc to within the statistical uncertainties of the data. We also validate the inference pipeline using two mock DESI ELG catalogues built from hydrodynamical (TNG300) and semi-analytical galaxy formation models (\texttt{L-Galaxies}). SHAMe-SF is able to reproduce the clustering of DESI-ELGs and the mock DESI samples within statistical uncertainties. We infer that DESI ELGs typically reside in haloes of $\sim 10^{11.8}h^{-1}$M$_{\odot}$ when they are central, and $\sim 10^{12.5}h^{-1}$M$_{\odot}$ when they are a satellite, which occurs in $\sim$30 \% of the cases. In addition, compared to the distribution of dark matter within halos, satellite ELGs preferentially reside both in the outskirts and inside haloes, and have a net infall velocity towards the centre. Finally, our results show evidence of assembly bias and conformity.

We propose that neutrons may be generated in high-energy, high-flux photon environments via photo-induced reactions on pre-existing baryons. These photo-hadronic interactions are expected to occur in astrophysical jets and surrounding material. Historically, these reactions have been attributed to the production of high-energy cosmic rays and neutrinos. We estimate the photoproduction off of protons in the context of gamma-ray bursts, where it is expected there will be sufficient baryonic material that may be encompassing or entrained in the jet. We show that typical stellar baryonic material, even material completely devoid of neutrons, can become inundated with neutrons in situ via hadronic photoproduction. Consequently, this mechanism provides a means for collapsars and other astrophysical sites containing substantial flux of high-energy photons to be favorable for neutron-capture nucleosynthesis.

From transmission electron microscopy and other laboratory studies of presolar grains, the implicit condensation sequence of carbon-bearing condensates in circumstellar envelopes of carbon stars is (from first to last) TiC-graphite-SiC. We use thermochemical equilibrium condensation calculations and show that the condensation sequence of TiC, graphite, and SiC depends on metallicity in addition to C/O ratio and total pressure. Calculations were performed for a characteristic carbon star ratio of C/O = 1.2 from 1E-10 to 1E-4 bars total pressure and for uniform metallicity variations ranging from 0.01 to 100 times solar elemental abundances. TiC always condenses before SiC, and the carbide condensation temperatures increase with increasing metallicity and total pressure. Graphite, however, can condense in a cooling circumstellar envelope before TiC, between TiC and SiC, or after SiC, depending on the carbon-bearing gas chemistry, which is dependent on metallicity and total pressure. Analytical expressions for the graphite, TiC, and SiC condensation temperatures as functions of metallicity and total pressure are presented. The inferred sequence from laboratory presolar grain studies, TiC-graphite-SiC, is favored under equilibrium conditions at solar and subsolar metallicities between ~1E-5 to 1E-8 bar total pressure within circumstellar envelopes of carbon stars with nominal C/O = 1.2. We also explored the dependence of the sequence at C/O ratios of 1.1 and 3.0 and found that as the C/O ratio increases, the TiC-graphite-SiC region shifts towards higher total pressures and lower metallicities.

We present an analysis of nine star-forming galaxies with $\langle z \rangle = 3.95$ from the JWST EXCELS survey for which we obtain robust chemical abundance estimates for the $\alpha$-elements O, Ne and Ar. The $\alpha$-elements are primarily produced via core-collapse supernovae (CCSNe) which should result in $\alpha$-element abundance ratios that do not vary significantly across cosmic time. However, Type Ia supernovae (SNe Ia) models predict an excess production of Ar relative to O and Ne. The Ar/O abundance ratio can therefore be used as a tracer of the relative enrichment of CCSNe and SNe Ia in galaxies. Our sample approximately doubles the number of sources with measurements of ${\rm Ar/O}$ at $z > 2$, and we find that our sample exhibits sub-solar Ar/O ratios on average, with $\rm{Ar/O} = 0.62 \pm 0.10 \, (\rm{Ar/O})_{\odot}$. In contrast, the average Ne/O abundance is fully consistent with the solar ratio, with $\rm{Ne/O} = 1.07 \pm 0.12 \, (\rm{Ne/O})_{\odot}$. Our results support a scenario in which Ar has not had time to build up in the interstellar medium of young high-redshift galaxies, which are dominated by CCSNe enrichment. We show that these abundance estimates are in good agreement with recent Milky Way chemical evolution models, and with Ar/O trends observed for planetary nebulae in the Andromeda galaxy. These results highlight the potential for using multiple element abundance ratios to constrain the chemical enrichment pathways of early galaxies with JWST.

We investigate Roche lobe overflow mass transfer (MT) in eccentric binary systems between stars and compact objects (COs), modeling the coupled evolution of both the star and the orbit due to eccentric MT (eMT) in a self-consistent framework. We implement the analytic expressions for secular rates of change of the orbital semi-major axis and eccentricity, assuming a delta function MT at periapse, into the binary stellar evolution code MESA. Two scenarios are examined: (1) a simplified model isolating the effects of eMT on stellar and orbital evolution, and (2) realistic binary configurations that include angular momentum exchange (e.g., tides, mass loss, spin-orbit coupling, and gravitational wave radiation). Unlike the ad hoc approach of instant circularization that is often employed, explicit modeling of eMT reveals a large fraction of binaries can remain eccentric post-MT. Even binaries which naturally circularize during eMT have different properties (donor mass and orbital size) compared to predictions from instant circularization, with some showing fundamentally different evolutionary outcomes (e.g., stable versus unstable MT). We demonstrate that a binary's initial mass ratio and eccentricity are predictive of whether it will remain eccentric or circularize after eMT. These findings underscore the importance of eMT in understanding CO-hosting binary populations, including X-ray binaries, gravitational wave sources, and other high-energy transients.

There has been global attention focused on extreme climatic changes. The purpose of this paper is to explore the response of extreme precipitation events to solar activity, over Kerala, India. The three solar indices - sunspot number, F10.7 index, and cosmic ray intensity - are examined, and their relationship to rainfall is examined during a 57-year period (1965 - 2021), starting with Solar Cycle 20. Both solar and rainfall data are considered on an annual scale as well as on a seasonal scale by dividing them into winter, pre-monsoon, monsoon, and post-monsoon seasons. The solar indices are used to calculate correlation coefficients with seasonal rainfall. Through correlation analysis, it is found that the precipitation in Kerala is correlated with the sunspot activity, but with different significance. When solar activity is high, the winter and monsoon seasons exhibit strong correlations with high significance. The solar influence at the regional level is also studied. The central and southern parts of Kerala appear to be influenced by the Sun during periods of high activity. The years with excess and deficiency of rainfall are calculated and compared with the solar indices. It was observed that the years with excessive and insufficient rainfall coincide with the years when the solar activity is at its highest or minimum. It is suggested that there is a physical link and a way to predict extreme rainfall events in Kerala based on the association between solar activity and those events.

We explore the possibility that exotic forms of dark matter could expose humans on Earth or on prolonged space travel to a significant radiation dose. The radiation exposure from dark matter interacting with nuclei in the human body is generally assumed to be negligible compared to other sources of background radiation. However, as we discuss here, current data allow for dark matter models where this is not necessarily true. In particular, if dark matter is heavier and more strongly interacting than weakly interacting massive particle dark matter, it could act as ionizing radiation and deposit a significant amount of radiation energy in all or part of the human population, similar to or even exceeding the known radiation exposure from other background sources. Conversely, the non-observation of such an exposure can be used to constrain this type of heavier and more strongly interacting dark matter. We first consider the case where dark matter scatters elastically and identify the relevant parameter space in a model-independent way. We also discuss how previous bounds from cosmological probes, as well as atmospheric and space-based detectors, might be avoided, and how a re-analysis of existing radiation data, along with a simple experiment monitoring ionizing radiation in space with a lower detection threshold, could help constrain part of this parameter space. We finally propose a hypothetical dark matter candidate that scatters inelastically and argue that, in principle, one per mille of the Earth's population could attain a significant radiation dose from such a dark matter exposure in their lifetime.

We study the detectability of GeV-band gamma-ray polarization with the AMS-02 experiment and a proposed successor, from Galactic and extragalactic sources. Characterizing gamma-ray polarization in this energy range could shed light on gamma-ray emission mechanisms in the sources; physics beyond the Standard Model, such as the presence of axion-like particles (ALPs), could also induce a distinctive energy-dependent polarization signal due to propagation effects in magnetic fields. We present estimates for the minimum detectable polarization from bright sources and the forecast reach for axion-like particles (ALPs). We show that for an example bright extragalactic source (NGC1275), AMS-02 will only have sensitivity to ALP-induced polarization from currently open parameter space if the B-field configuration is unusually favorable to a signal. However, a successor experiment such as AMS-100 would be expected to probe new parameter space even for pessimistic B-field models, with prospects to measure the energy-dependence of such a signal. For Galactic sources, polarization measurements could provide a unique test of scenarios where ALPs induce energy-dependent features in the photon intensity. However, in the absence of a bright transient source (such as a Galactic supernova), the parameter space that would be probed by this approach with ten years of AMS-100 data is already nominally excluded by other experiments, although this conflict may be avoided in specific ALP models.

In this work, we have studied the medium effects in strange quark matter in the framework of a grand-canonical ensemble using the phenomenological quasi-particle model. This model is studied with proper self-consistent thermodynamical treatment by incorporating chemical potential-dependent quark mass. We have also included the vector interaction in a self-consistent way. The main aim of this work is to explore the proper thermodynamic treatment in addressing the medium effects at both zero and finite temperatures. In the case of the finite temperature, we explore the study of self-consistent thermodynamics in the isothermal as well as the isentropic processes. The effect of finite temperature and lepton fraction have been studied on the equation of state, speed of sound, and particle fraction. The $M-R$ and $M-\Lambda$ diagrams are found to be consistent with the observational constraints.

We propose that modifications to the Higgs potential within a narrow atmospheric layer near the event horizon of an astrophysical black hole could significantly enhance the rate of sphaleron transitions, as well as transform the Chern-Simons number into a dynamic variable. As a result, sphaleron transitions in this region occur without suppression, in contrast to low-temperature conditions, and each transition may generate a substantially greater baryon number than would be produced by winding around the Higgs potential in Minkowski spacetime. This effect amplifies baryon number violation near the black hole horizon, potentially leading to a considerable generation of matter. Given the possibility of a departure from equilibrium during the absorption of matter and the formation of relativistic jets in supermassive black holes, we conjecture that this process could contribute to the creation of a significant amount of matter around such black holes. This phenomenon may offer an alternative explanation for the rapid growth of supermassive black holes and their surrounding galaxies in the early Universe, as suggested by recent observations from the JWST. Furthermore, this mechanism may provide insights into the low-mass gap puzzle, addressing the observed scarcity of black holes with masses near the Oppenheimer-Volkoff limit.

Interest on the possible future scenarios the universe could have has grew substantially with breakthroughs on late-time acceleration. Holographic dark energy (HDE) presents a very interesting approach towards addressing late-time acceleration, presenting an intriguing interface of ideas from quantum gravity and cosmology. In this work we present an extensive discussion of possible late-time scenarios, focusing on rips and similar events, in a universe with holographic dark energy. We discuss these events in the realm of the generalized Nojiri-Odintsov cutoff and also for the more primitive holographic cutoffs like Hubble, particle and event horizon cutoffs. We also discuss the validity of the generalized second law of thermodynamics and various energy conditions in these regimes. Our work points towards the idea that it is not possible to have alternatives of the big rip consistently in the simpler HDE cutoffs, and shows the flexibility of the generalized HDE cutoff as well.

Parametrized nucleon density distributions are widely employed for the calculation of the properties of atomic nuclei and dense inhomogeneous matter in compact stars within the Thomas-Fermi method and its extensions. We show that the use of insufficiently smooth parametrizations may deteriorate the accuracy of this method. We discuss and clarify the smoothness condition using the example of the so-called "nuclear pasta" in the neutron star mantle.

As density increases, the shape of nuclei transitions to non-spherical ``nuclear pasta" structures. The physical properties of the nuclear pasta, such as thermal conductivity and elasticity, have implications for detecting continuous gravitational waves from a rapidly rotating neutron star. In this work, we investigate the effect of the nuclear pasta on the quadruple moment, and find out that, compared with previous work, the quadrupole moment contributing to continuous gravitational-wave radiation can be up to two orders of magnitude larger. We also discuss the relationship between the quadruple moment and the maximum shear strain. Considering the properties of nuclear pasta, we study the detectability of known accreting neutron stars and compare predicted results to the detectable amplitude limits. These sources are well above the sensitivity curves for Cosmic Explorer and Einstein Telescope detectors. Our work advances the understanding of the properties of nuclear pasta and a possible mechanism for continuous gravitational waves.

We investigate the impact of preheating on baryogenesis in $R^2$-Higgs inflation. In this scenario, the inclusion of a dimension-six operator ${(R/ \Lambda^2)} B_{\mu\nu} \widetilde{B}^{\mu\nu} $ abundantly generates helical hypermagnetic fields during inflation, leading to a baryon asymmetric Universe at the electroweak crossover. Focusing on the $R^2$-like regime, we first derive the relevant dynamics of preheating using a doubly-covariant formalism. We find that preheating can happen for the Higgs, transverse gauge and Goldstone bosons, however, it is dependent on the value of the non-minimal coupling $\xi_H$ between the Standard Model Higgs field and the Ricci scalar. We identify the preheating temperature to determine the appropriate scale $\Lambda$ for driving baryogenesis, which is around $\Lambda \sim 2.2 \, (2.6) \times 10^{-5}\, M_{\rm P}$ for $\xi_H \sim 1 \, (10)$. Our results represent the most accurate estimation of the scale of gravity induced baryogenesis in $R^2$-Higgs inflation to date. Areas for further improvement are identified.

We explore cosmological particle production associated with inflationary fluctuations by comparing gravitational and geometric mechanisms, within a non-minimal Yukawa-like coupling between a inflaton and spacetime curvature. We show under which circumstances the number of geometric particles is comparable to the purely gravitational contribution by introducing the S-matrix formalism and approximating the inflationary potentials through power series. Despite the geometric production is a second-order effect, we show that it cannot be neglected \emph{a priori}, emphasizing that throughout inflation we do expect geometric particles to form as well as in the reheating phase. This result is investigated in both the Jordan and Einstein frames, selecting inflationary potentials supported by the Planck Satellite outcomes, \textit{i.e.}, the Starobinsky, hilltop, $\alpha$-attractor, and natural inflationary paradigms. We notice that, for large field approaches, the only feasible coupling may occur in case of extremely small field-curvature coupling constants, while the small field frameworks, namely the hilltop and $\alpha$-attractor models with quartic behavior, are essentially ruled out since they do not appear dynamically viable. We then point out that, while dynamically there exists a net equivalence between the Jordan and Einstein frames, the number of particles appears quite different passing from a representation to another one, thus pointing out the existence of a possible \emph{quantum frame issue}. In summary, while the classical inflationary dynamics is equivalently described in the Jordan and Einstein frames, a viable physical description of particle production valid in both the frames may be hindered by the absence of a complete quantum gravity. The latter could therefore be seen as missing puzzle to address the longstanding challenge of consistently passing between the two frames.

Recently, a perturbative calculation to the first post-Newtonian order has shown that the analytically worked out Lense-Thirring precession of the orbital angular momentum of a test particle following a circular path around a massive spinning primary is able to explain the measured features of the jet precession of the supermassive black hole at the centre of the giant elliptical galaxy M87. It is shown that also the hole's mass quadrupole moment $Q_2$, as given by the no-hair theorems, has a dynamical effect which cannot be neglected, as, instead, done so far in the literature. New allowed regions for the hole's dimensionless spin parameter $a^\ast$ and the effective radius $r_0$ of the accretion disk, assumed tightly coupled with the jet, are obtained by including both the Lense-Thirring and the quadrupole effects in the dynamics of the effective test particle modeling the accretion disk. One obtains that, by numerically integrating the resulting averaged equations for the rates of change of the angles $\eta$ and $\phi$ characterizing the orientation of the orbital angular momentum with $a^\ast = +0.98$ and $r_0=14.1$ gravitational radii, it is possible to reproduce, both quantitatively and qualitatively, the time series for them recently measured with the Very Long Baseline Interferometry technique. Instead, the resulting time series produced with $a^\ast = -0.95$ and $r_0=16$ gravitational radii turn out to be out of phase with respect to the observationally determined ones, while maintaining the same amplitudes.

Rotating neutron stars (NSs) are crucial objects of study, as our understanding of them relies significantly on observational data from these rotating stars. Observations suggest that the magnetic fields of NSs range from approximately $10^{8-15}$ G. In this work, we compute the Kepler frequency and moment of inertia for rotating NSs under the influence of a chaotic magnetic field. We utilize an equation of state (EOS) incorporating nuclei in the crust and hyperons in the core, with the Hartle-Thorne formalism applied to address the rotational aspects. A magnetic field ansatz is selected, in which the magnetic field is coupled to the energy density. To examine the impact of a chaotic magnetic field on the Kepler frequency and moment of inertia, we vary the magnetic field strength. Our results indicate that an increase in magnetic field strength enhances the Kepler frequency of rotating NSs. For the moment of inertia, the effect of magnetic field variation is minimal at lower masses but becomes more pronounced as the mass exceeds $M=0.5 M_\odot$, where moment of inertia increases with increasing magnetic field. Furthermore, our results for the moment of inertia comply with constraint derived from pulsar mass measurements, data from gravitational wave events GW170817 and GW190425, and X-ray observations of emission from hotspots on NS surfaces measured by NICER.

Dark Yang-Mills sectors that confine to form stable composite states, known as glueballs, have been traditionally proposed as a potential explanation for cosmological Dark Matter (DM). Earlier studies have established viability of the lightest scalar glueball as a possible DM candidate. In this work, we explore a whole class of effective composite sectors in the confined Yang-Mills regime featuring an additional pseudoscalar glueball state. We also investigate the role of effective interactions of the dark glueball sector with the visible sectors via higher-dimensional operators primarily focusing on dimension-8 couplings of glueballs to photons and gluons. We stress the remarkable similarities between the phenomenology of such glueball effective theories and Standard Model extensions featuring Axion-Like Particles (ALPs). Hence, one deals with a new class of composite Glueball ALPs (or GALPs) coupled to photons and/or nucleons in a wide mass range, from sub-eV to the Planck scale, yielding viable DM candidates that can be probed by astrophysical and cosmological observations.

We present an exact solution to standard model hydrodynamic cosmological perturbation theory in a matter-dominated era that is taken to be adiabatic. The solution is in the form of hypergeometric functions. While such functions can oscillate they do not appear to oscillate with the acoustic sound velocity. We show that for the model the hydrodynamic assumption is only valid at low frequencies, with viscous effects being needed in order to maintain the covariant conservation of the perturbed energy-momentum tensor.