Papers for Monday, Mar 10 2025

We present first results and catalogs from the HST-Hyperion survey. This survey has collected 50 orbits of WFC3/F160W imaging and WFC3/G141 grism spectroscopy in the most overdense regions of the Hyperion proto-supercluster at $z\sim2.45$, which are analyzed in conjunction with the adjacent 56 orbits of WFC3/F140W imaging and WFC3/G141 grism spectroscopy from the 3D-HST survey. Sources were identified and spectra extracted using GRIZLI, which subsequently fit the combined grism data with object-matched photometric data from the COSMOS2020 catalog to obtain a redshift and best-fit spectral model. Each source was then visually inspected by multiple team members and quality flags were assigned. A total of 12814 objects with $m_{HST} \leq 25.0$ were inspected, of which 5629 (44%) have reliable redshifts from the grism data, which are sensitive to emission lines at a level of $\sim8.8 \times10^{-18}$ erg s$^{-1}$ cm$^{-2}$ ($1\sigma$). Comparison to high-quality ground-based spectroscopic redshifts yields a scatter of $\sigma_{\rm NMAD} = 0.0016$. The resulting catalogs contain 125 confirmed members of the Hyperion structure within $2.40<z<2.53$, with an additional 71 confirmed galaxies in projection within $2.35<z<2.65$. The redshift, stellar population, and line flux catalogs, as well as all grism spectra, are publicly available.

We study the impact of molecular (${\rm H_2}$) and atomic (HI) hydrogen cooling on the galaxy formation threshold. We calculate the fraction of dark matter (DM) halos that exceed a critical mass required for star formation, $M_{\mathrm{crit}}(z)$, as a function of their peak mass. By convolving analytic halo mass accretion histories (MAHs) with models for $M_{\mathrm{crit}}(z)$, we predict that halos with peak virial masses below $\sim 10^8~M_{\mathrm{\odot}}$ can form stars before reionization through ${\rm H_2}$ cooling. These halos remain dark when only HI cooling and reionization are modeled. However, less than $\approx 10\%$ of halos with peak masses below $\sim 10^{7}~M_{\mathrm{\odot}}$ ever exceed $M_{\mathrm{crit}}(z)$, even when ${\rm H_2}$ cooling is included; this threshold is primarily set by relative streaming motion between DM and baryons imprinted at recombination. We obtain similar results using subhalo MAHs from an extremely high-resolution cosmological DM--only zoom-in simulation of a Milky Way (MW) analog (particle mass $6.3\times 10^3~M_{\mathrm{\odot}}$). Based on the abundance of MW satellites, these results imply that at least some known ultra-faint dwarf galaxies formed through ${\rm H_2}$ cooling. This work sharpens predictions for the galaxy formation threshold and demonstrates how its essential features emerge from the underlying distribution of halo growth histories.

We present Data Release 6 of ThrUMMS, consisting of complete data cubes and various moments of line emission ($^{12}$CO, $^{13}$CO, C$^{18}$O) from molecular clouds, across 60$^{\circ}$$\times$2$^{\circ}$ of the Fourth Quadrant (4Q) of the Milky Way at a resolution of 72$''$ in (l,b) and 0.09 kms$^{-1}$ in V$_{LSR}$. From LTE radiative transfer analysis of the data cubes, we compute cubes and moments of the lines' opacity, excitation temperature, and column density $N_{12CO}$. Combining $I_{12CO}$ and $N_{12CO}$ data, we derive a global mass conversion law $N$=$N_{0}I^{p}$, where $N_{0}$$\approx$10$^{18}$mol/m$^{2}$ and $p$=2 at this resolution. We argue that the standard linear $N$=$XI$ is only approximately valid: $p$$\sim$1.5-1.0 at coarser resolutions or in atypical locations, such as Galactic Center clouds. Also, the velocity dispersion distributions are very different between $I_{12CO}$ and $N_{12CO}$, the former preferentially tracing more diffuse molecular gas. We re-evaluated Galactic rotation parameters for the 4Q, defining a new ``BGT'' model, and deprojected the (l,V) data onto (l,d) and (x,y) grids using standard kinematic procedures. To automate distance disambiguation inside the solar circle, we developed a simple $\zeta^{+}$ discriminator function and applied it to our deprojections. We discovered two previously unrecognised features of the molecular cloud population: widespread ripples in the midplane of wavelength 4kpc and amplitude 50pc, potentially generated by the last perigalactic passage of the Sgr dwarf; and three distant, massive molecular structures, the Far Ara clouds, two of which exhibit an exceptional velocity gradient, possibly arising in a massive spiral feather or a gas-rich dwarf galaxy $\sim$20--300kpc beyond the disk.

We present measurements of the spatially averaged HeII photo-ionization rate ($\langle \Gamma_{\rm HeII} \rangle$), mean free path of HeII ionizing photons ($\lambda_{\rm mfp, HeII}$), and HeII fraction ($f_{\rm HeII}$) across seven redshift bins within the redshift range $2<z<4$. The measurements are obtained by comparing the observed effective optical depth distribution of HeII ($\tau_{\rm eff, HeII}$) with models generated by post-processing of the Sherwood simulation suite using our code EXCITE. With EXCITE, we efficiently explore a large parameter space ($\sim 15000$ models) by varying $\lambda_{\rm mfp, HeII}$ and $\langle \Gamma_{\rm HeII} \rangle$. We employ Anderson-Darling test for the cumulative distribution of $\tau_{\rm eff, HeII}$ to simultaneously measure $\lambda_{\rm mfp, HeII}$ and $\langle \Gamma_{\rm HeII} \rangle$. Our measurements account for possible observational and modeling uncertainties stemming mainly from the finite signal-to-noise ratio of the observed data and thermal parameter uncertainties. We find significant evolution, with the best-fit $\langle \Gamma_{\rm HeII} \rangle$ and $\lambda_{\rm mfp, HeII}$ decreasing by factors of $\sim 4.32$ and $ \sim 3.27$, respectively, from $z = 2.88$ to $z = 3.16$. Based on these measurements, we constrain the emissivity at the HeII ionization frequency ($\epsilon_{228}$) and HeII ionizing photon emission rate ($\dot{n}$), finding consistency with results from galaxy and QSO surveys. Comparison of our measured parameters with widely used uniform UVB models supports a scenario where HeII reionization is not completed before $z\sim2.74$. Our measured evolution is complementary and in good agreement with recent measurements of thermal parameters of the IGM, suggesting a coherent picture of rather late and rapid HeII reionization.

We explore the evolution of galaxy sizes at high redshift ($3<z<13$) using the high-resolution THESAN-ZOOM radiation-hydrodynamics simulations, focusing on the mass range of $10^6\,\mathrm{M}_{\odot} < \mathrm{M}_{\ast} < 10^{10}\,\mathrm{M}_{\odot}$. Our analysis reveals that galaxy size growth is tightly coupled to bursty star formation. Galaxies above the star-forming main sequence experience rapid central compaction during starbursts, followed by inside-out quenching and spatially extended star formation that leads to expansion, causing oscillatory behavior around the size-mass relation. Notably, we find a positive intrinsic size-mass relation at high redshift, consistent with observations but in tension with large-volume simulations. We attribute this discrepancy to the bursty star formation captured by our multi-phase interstellar medium framework, but missing from simulations using the effective equation-of-state approach with hydrodynamically decoupled feedback. We also find that the normalization of the size-mass relation follows a double power law as a function of redshift, with a break at $z\approx6$, because the majority of galaxies at $z>6$ show rising star-formation histories, and therefore are in a compaction phase. We demonstrate that H$\alpha$ emission is systematically extended relative to the UV continuum by a median factor of 1.7, consistent with recent JWST studies. However, in contrast to previous interpretations that link extended H$\alpha$ sizes to inside-out growth, we find that Lyman-continuum (LyC) emission is spatially disconnected from H$\alpha$. Instead, a simple Strömgren sphere argument reproduces observed trends, suggesting that extreme LyC production during central starbursts is the primary driver of extended nebular emission.

Axions have emerged as compelling candidates for describing the dark sector of the Universe. In this work, we explore quintessence models inspired by axion-like potentials as a dynamical alternative to the cosmological constant. These models naturally exhibit a tracking behaviour, reducing the need for fine-tuned initial conditions. We perform a Markov chain Monte Carlo (MCMC) analysis on a complete cosmological dataset of Planck PR4 cosmic microwave background (CMB), DESI DR1 baryon acoustic oscillation (BAO), Pantheon+ type Ia supernovae, low-$z$ Cepheid anchors, and DES Y1 large scale structure measurement. Unfortunately, neither the Hubble tension nor the $S_8$ tension is eased. The model does reach parity with $\Lambda$CDM model statistically according to DIC, WAIC and Bayesian ratio, suggesting that a quintessence model may still help with the cosmic tension by further extending the model we have investigated.

Omega Centauri ($\omega$ Cen) is the Milky Way's most massive globular cluster and is likely the stripped nucleus of an accreted dwarf galaxy. In this paper, we analyze $\omega$ Cen's kinematics using data from oMEGACat, a comprehensive catalog of $\omega$ Cen's central regions, including 1.4 million proper motion measurements and 300,000 spectroscopic radial velocities. Our velocity dispersion profiles and kinematic maps are consistent with previous work but improve on their resolution, precision, and spatial coverage. The cluster's 3D dispersion is isotropic in the core, with increasing radial anisotropy at larger radii. The 2D kinematic maps show an elongation of the velocity dispersion field comparable to the flattening observed photometrically. We find good agreement between proper motions and line-of-sight velocity dispersion and measure a kinematic distance of 5494$\pm$61 pc, the most precise kinematic distance to $\omega$ Cen available. The subset of data with precise metallicity measurements shows no correlation between metallicity and kinematics, supporting the picture of well-mixed stellar populations within the half-light radius of $\omega$ Cen. Finally, we study the degree of energy equipartition using a large range of stellar masses. We find partial energy equipartition in the center that decreases towards large radii. The spatial dependence of the radial energy equipartition is stronger than the tangential energy equipartition. Our kinematic observations can serve as a new reference for future dynamical modeling efforts that will help to further disentangle the complex mass distribution within $\omega$ Cen.

Dust attenuation in galaxies has often been used as a proxy for the extinction of point sources, such as supernovae, even though this approach ignores fundamental differences between the two cases. We present an analysis of the impact of geometric effects and scattering within dusty media on recovered galaxy dust properties. We use SKIRT, a radiative transfer code, to simulate observations of point sources embedded in dust clouds, as well as spiral and elliptical galaxies. We examine various galaxy morphologies, inclinations, and instrument apertures. We find that in galaxies the scattering of light into the line of sight and the presence of sources at different depths within the galaxy make attenuation fundamentally different from extinction. For a medium with intrinsic extinction slope Rv=3.068, we recover effective attenuation slopes Rv_e ranging from 0.5 to 7, showing that the two quantities are not analogous, even for local resolved observations. We find that Rv_e greatly depends on dust density, galaxy morphology, and inclination, the latter being the most significant. A single simulated galaxy, viewed from different angles, can reproduce the well-known relation between attenuation strength Av_e and Rv_e observed for star-forming galaxy samples. An increase in dust density leads to higher Rv_e across all inclinations, which, assuming a correlation between stellar mass and dust density, explains the increase in Rv_e with mass observed in star-forming galaxies. However, we are unable to explain the differences in Rv_e between star-forming and quiescent high-mass galaxies. We conclude that highly attenuated regions of simulated face-on galaxies yield Rv_e within 10% of the intrinsic extinction slope of the medium, allowing for the distinction of different dust types. For edge-on spirals, however, the median Rv_e for low Av_e regions appears to better approximate the extinction slope.

We present a study of the galaxy merger and interaction activity within the Hyperion Proto-supercluster at z~2.5 in an effort to assess the occurrence of galaxy mergers and interactions in contrast to the coeval field and their impact on the build up of stellar mass in high density environments at higher-z. For this work, we utilize data from the Charting Cluster Construction with VUDS and ORELSE Survey (C3VO) along with extensive spectroscopic and photometric datasets available for the COSMOS field, including the HST-Hyperion Survey. To evaluate potential merger and interaction activity, we measure the fraction of galaxies with close kinematic companions ($f_{ckc}$) both within Hyperion and the coeval field by means of a Monte Carlo (MC) methodology developed in this work that probabilistically employs our entire combined spectroscopic and photometric dataset. We validate our $f_{ckc}$ MC methodology on a simulated lightcone built from the GAlaxy Evolution and Assembly semi-analytic model, and we determine correction factors that account for the underlying spectroscopic sampling rate of our dataset. We find that galaxies in Hyperion have close kinematic companions $\gtrsim 2\times$ more than galaxies in the field and measure a corrected $f_{ckc}=49_{-7.8}^{+7.4}$% for Hyperion and a corrected $f_{ckc}=23_{-1.3}^{+1.2}$% for the surrounding field; a $>3\sigma$ difference. This increase in $f_{ckc}$ indicates an enhancement in the merger and interaction activity within Hyperion and matches the trend seen in other structures. The rate of merger and interactions within the field implied from our field $f_{ckc}$ measurement is well aligned with values measured from other observations in similar redshift ranges. The enhanced $f_{ckc}$ measured within Hyperion suggests that merger and interaction activity play an important role in the mass growth of galaxies in denser environments at higher z.

The mass-metallicity relation (MZR) is a fundamental scale law of galaxies. It is observed to evolve with redshift in unresolved galaxies up to z>6. However, observational constraints limits our view at such early epochs to galaxies with M_* >= 10^7 M_Sun. On the other hand, in the local Universe the MZR can be traced down to the faintest end of the galaxy luminosity function (M_*= 10^2 M_Sun) but we have access only to its present-day realization. We propose to use RR Lyrae stars to get the mean metallicity of local dwarf galaxies at the early epoch in which these variable stars were formed (z>~3), opening a new window on the evolution of the MZR across cosmic times down to the lowest mass. We use available data for a sample of Milky Way satellites to show that indeed the evolution of the MZR from the epoch of the formation of RR Lyrae to the present day can be traced with this approach, with results broadly compatible with those inferred from high z galaxies from nebular emission lines.

R-process enhanced metal-poor stars (\EuFe$\geq+0.3$ and \FeH$\leq-1.0$) are rare objects whose study can provide clues to the astrophysical sites of the rapid neutron capture process. In this study, we investigate the detailed chemical abundance patterns of two of these anomalous stars, originally identified among stars observed by the GALAH survey. Our aim is to obtain the detailed chemical abundance pattern of these stars with spectroscopy at higher resolution and signal-to-noise ratio. We use a calibration of the infrared flux method to determine accurate effective temperatures, and \Gaia~ parallaxes together with broadband photometry and theoretical bolometric corrections to determine surface gravity. Metallicities and chemical abundances are determined with model atmospheres and spectrum synthesis. We also integrate stellar orbits for a complete chemodynamic analysis. e determine abundances for up to 47 chemical species (44 elements), of which 27 are neutron-capture elements. Corrections because of deviations from the local thermodynamical equilibrium are applied to the metallicities and 12 elements. We find that one of the stars, BPS CS 29529-0089, is a proto-disk star of the Milky Way of r-II type, with \EuFe=+1.79~dex. The second star, TYC 9219-2422-1, is part of the halo and associated with the Gaia-Sausage-Enceladus merger event. It is of r-I type with [Eu/Fe] = +0.54. Abundances of Th are also provided for both stars. BPS CS 29529-0089 is the most extreme example of r-process enhanced star known with disk-like kinematics and that is not carbon enhanced. TYC 9219-2422-1 is found to be an archetypal Gaia-Sausage-Enceladus star. Their abundances of C, Mg, Ni, Sc, Mn, and Al seem consistent with expectations for stars enriched by a single population III core collapse supernova, despite their relatively high metallicities ([Fe/H] $\sim$ $-$2.4).

We explore the potential of lunar-based gravitational-wave detectors to broaden the multi-messenger astrophysics landscape by detecting mergers of massive ($\gtrsim 1~M_{\odot}$) double white dwarf (WD) binaries. These systems are potential progenitors of Type Ia supernovae and could serve as independent probes of cosmic expansion. We examine two proposed lunar gravitational-wave detector concepts operating in the sub-hertz band (0.1-1 Hz): the Gravitational-Wave Lunar Observatory for Cosmology (a proxy for suspended test mass detectors) and the Lunar Gravitational-Wave Antenna (a proxy for seismic array detectors). Using both contact and Roche lobe overflow merger scenarios, we estimate that these detectors could reach distances of up to ~1 Gpc for the most massive mergers. We show that lunar detectors could observe up to dozens of massive WD mergers annually, including those originating from globular clusters. Lunar detectors would constrain the masses of these WDs with an unprecedented accuracy of one part in a million. Furthermore, these detectors would provide early warnings of weeks before merger, including sky-localization of square arcminute resolution, enabling a new era of coordinated multi-messenger follow-up of electromagnetic transients-whether they evolve into Type Ia supernovae or accretion-induced collapse events.

Light pollution, a rapidly escalating anthropogenic phenomenon driven by the excessive and often inefficient use of artificial lighting, has profound implications for astronomy, ecology, and human health. This study presents the first comprehensive characterization of night sky quality in Colombia, focusing on sites of astronomical and ecological significance. The selected locations include the Astronomical Observatory of UTP, the Tatacoa Desert, the Bogotá Botanical Garden, and Cerro Guadalupe. Utilizing the Sky Quality Camera, we collected all-sky data to measure surface brightness and correlated color temperature of the night sky. Our findings reveal a significant loss of natural sky visibility in urban areas and demonstrate the detrimental effects of artificial lighting on critical astronomical sites such as La Tatacoa. This study provides a crucial foundation for future research and informs the development of public policies aimed at preserving the night sky.

This work introduces an advanced technique optimized for detecting photons generated by charged particles, leveraging Skipper-CCD sensors. By analyzing background sources and detection efficiencies, the technique achieves strong agreement between experimental results and Cherenkov-based simulations. It also provides a robust framework for investigating secondary photon production in environments with high fluxes of ionizing particles, such as those anticipated in space-based astronomical instruments. These secondary photons present a critical challenge as background noise for next-generation single-photon resolving imagers used to study faint celestial objects. Furthermore, the method exhibits significant potential for broader applications, including exploring photon generation in various substrate materials and examining their transport through multiple interfaces.

Models predict that atomic carbon occurs at the surface and in the process of the formation of molecular clouds, making its fine structure transitions a diagnostic of cloud formation. We study the distribution of atomic carbon in a small inconspicuous region towards the outer Galaxy that might be representative for a large fraction of the molecular gas of the Milky Way that is not directly affected by star formation. We observed a small strip of 5 arcminutes in the ``Forgotten Quadrant'', the third quadrant of the Milky Way, with the APEX telescope in the $^3P_1-^3P_0$ [CI] transition of atomic carbon and the $J=2-1$ transition of the three most abundant CO isotopologues and compared their distribution with existing measurements of gas column density and of ionized carbon. The atomic carbon shows a very smooth distribution with the smallest gradient along the strip compared to the other lines. It is always brighter than $^{13}$CO and in one velocity-component even brighter than CO. In contrast to observations of many star-forming regions, the [CI] emission seems to extend beyond the molecular gas, in line with the models of photon-dominated regions (PDRs). However, a standard PDR model fit to the observations fails because the models either predict more molecular gas, traced through C$^{18}$O, or more diffuse gas, traced through [CII], than observed. The carbon-budget in the gas phase does not add up to the same column seen through dust emission. To understand the [CI] emission from galaxies it is necessary to get the full statistics for the quiescent gas outside of the star-forming regions that behaves significantly different from dense gas exposed to high ultraviolet fields.

The magnetic field morphology of relativistic jets can be studied with circular polarization (CP). Recent 3D relativistic magnetohydrodynamic (RMHD) simulations coupled with radiative transfer calculations make strong predictions about the level (and morphology) of the jet's CP emission. These simulations show that the sign of CP and the electric vector position angle (EVPA) are both sensitive to the jet's magnetic field morphology within the radio core. We probe this theory by exploring if the jet's radio core EVPA orientation is consistent with the observed sign of the core CP in deep full-track polarimetric observations. We aim to probe the nature of linear polarization and CP in the innermost regions of jets from a small sample of nine blazars. This sample includes sources that have exhibited: (i) positive CP, (ii) negative CP, or (iii) positive & negative CP simultaneously in the radio core region. Nine blazar sources were observed using the VLBA at both 15 GHz and 23 GHz. Our self-calibration relies on a physically based model applied in DoG-HiT resulting in more accurate gains. We consider compact Stokes V structures instead of assuming it to be zero, which is crucial given the significant non-zero CP fraction observed at long baselines. We observe robust, relatively high degrees of fractional circular polarization m_c=(0.32 +- 0.2)% at 15 GHz and m_c=(0.59 +-0.56)% at 23 GHz. We observe consistent polarized structure and EVPA orientation over time when comparing our analysis with archival MOJAVE data. Theoretical predictions indicate a clear favored toroidal magnetic field orientation within the extended jet emission of the reconstructed signal of the blazar 0149+218. The jet structures of 1127-145 and 0528+134, even in superresolution, exhibit characteristics aligned with helical or poloidal magnetic nature.

The Galactic Bulge Time Domain Survey (GBTDS) of the Roman Space Telescope will take high cadence data of the Galactic bulge. We investigate the asteroseismic potential of this survey for red giants. We simulate the detectability of global asteroseismic frequencies, $\nu_{\mathrm{max}}$ and $\Delta\nu$, by modify ing Kepler data to match nominal GBTDS observing strategies, considering different noise models, observing cadences, and detection algorithms. Our baseline case, using conservative assumptions, consistently leads to asteroseismic $\nu_{\mathrm{max}}$ detection probabilities above 80% for red clump and red giant branch stars brighter than 16th magnitude in Roman's F146 filter. We then inject these detection probabilities into a Galaxia model of the bulge to estimate asteroseismic yields. For our nominal case, we detect 290,000 stars in total, with 185,000 detections in the bulge. Different assumptions give bulge yields from 135,000 to 349,000 stars. For stars with measured $\nu_{\mathrm{max}}$, we find that we can recover $\Delta\nu$ in 21% to 42% of red clump stars, and 69% to 92% of RGB stars. Implications for survey strategy and asteroseismic population studies are discussed more.

We investigate the physical properties and detectability of warm-hot intergalactic medium (WHIM) gas with temperatures in the range $10^5<T<10^7$K around galaxy clusters using simulated galaxy clusters from The Three Hundred project. In simulations with different input physics (GIZMO-SIMBA and Gadget-X), we consistently find that the median gas temperature decreases to the WHIM upper bound, $10^7$K, at $\sim 2 \times R_{200c}$, while the WHIM mass fraction increases with radius until $\sim 3\times R_{200c}$, where it plateaus at $\sim 70$ per this http URL simulating X-ray emission from all gas components, we find that the WHIM contribution to the soft X-ray band (0.2 - 2.3 keV) increases with radius but eventually plateaus at larger distances. The differences between the two simulations become more pronounced at higher redshifts and larger radii. Finally, after accounting for observational effects, primarily by removing (sub)halos, we predict that the signal-to-noise ratio of the X-ray signal obtained by stacking the eRASS1 galaxy cluster catalogue will be $\sim 7$ for GIZMO-SIMBA and $\sim 21$ for Gadget-X.

We report the multi-band photometric observations of the Type IIb supernova (SN) 2024iss with ultra-violet (UV), optical, and near-infrared (NIR) wavelengths starting one day after the explosion. The UV and optical light curves show the first peak two days after the explosion date. Following a first peak, a secondary maximum is observed in the optical and NIR bands, similar to SNe IIb with double-peaked light curves. The quasi-bolometric light curve shows the fast decay until a week after the explosion. From the analysis of the bolometric light curve, the ejecta mass and kinetic energy are estimated to be $M_{ej}=2.8\pm0.6~M_{\odot}$ and $E_{kin}=9.4\pm4.1\times10^{50}$ erg. The mass of the radioactive $^{56}$Ni is estimated to be $M(^{56}Ni)=0.2~M_{\odot}$. Fitting a black-body function to the spectral energy distribution reveals that the photospheric temperature exhibits a rapid exponential decline during the first week after the explosion. An analytic model describing the cooling emission after shock breakout provides a reasonable explanation for the observed temperature evolution. From these ejecta parameters, we calculated the progenitor radius to be $R_{pro}=50-340$~$R_{\odot}$. We conclude that these explosion properties are consistent with a core-collapse explosion from a yellow supergiant (YSG) progenitor.

We present a population-level view of volatile gas species (H$_2$, He, H$_2$O, O$_2$, CO, CO$_2$, CH$_4$) distribution during the sub-Neptune to rocky planet transition, revealing in detail the dynamic nature of small planet atmospheric compositions. Our novel model couples the atmospheric escape model $\texttt{IsoFATE}$ with the magma ocean-atmosphere equilibrium chemistry model $\texttt{Atmodeller}$ to simulate interior-atmosphere evolution over time for sub-Neptunes around G, K and M stars. Chiefly, our simulations reveal that atmospheric mass fractionation driven by escape and interior-atmosphere exchange conspire to create a distinct oxidation gradient straddling the small-planet radius valley. We discover a key mechanism in shaping the oxidation landscape is the dissolution of water into the molten mantle, which shields oxygen from early escape, buffers the escape rate, and leads to oxidized secondary atmospheres following mantle outgassing. Our simulations reproduce a prominent population of He-rich worlds along the upper edge of the radius valley, revealing that they are stable on shorter timescales than previously predicted. Our simulations also robustly predict a broad population of O$_2$-dominated atmospheres on close-in planets around low mass stars, posing a potential source of false positive biosignature detection and marking a high-priority opportunity for the first-ever atmospheric O$_2$ detection. We motivate future atmospheric characterization surveys by providing a target list of planet candidates predicted to have O$_2$-, He-, and deuterium-rich atmospheres.

This document provides a user guide for reducing UVIT data using CCDLAB. While CCDLAB offers a straightforward data reduction work-flow, users may encounter certain challenges that require additional guidance. This guide provides instructions by addressing common issues related to key processing steps, including WCS solutions and VIS drift tracking.

The Global Oscillations at Low Frequencies instrument aboard the Solar and Heliospheric Observatory has provided over two decades of continuous, high-precision data, enabling detailed measurements of the Sun's oscillation frequencies. These oscillations, analyzed through Doppler velocity shifts, offer invaluable insights into the Sun's internal structure and dynamics using the methods of helioseismology. This methodology has been extended beyond the Sun to the study of other stars, leveraging data from various space missions. Notably, NASA's Kepler mission, in operation from 2009 until 2018, observed over 500,000 stars, analyzing brightness variations over time and generating a vast database for asteroseismic studies. This investigation focuses on the solar-type star KIC 6106415, comparing its oscillation frequencies with those derived from GOLF data. By analyzing frequency patterns and mode lifetimes, we explore the similarities and differences in internal structures, stellar evolution, and magnetic activity cycles between KIC 6106415 and the Sun. Our analysis reveals that KIC 6106415 exhibits starspot numbers similar to the Sun, peaking at an estimated 175, which is consistent with its faster rotation rate. The data suggest that KIC 6106415 may have shorter magnetic activity cycles than the Sun, reinforcing the established link between stellar rotation and magnetic field generation in solar-type stars.

We have observed the $^{13}$CH$_3$OH $5_1-4_1$ A$^+$, $^{13}$CH$_3$OH $14_1-13_2$ A$^-$, and CH$_2$DOH $8_{2,6}-8_{1,7}$ $e_0$ lines toward 24 high-mass star-forming regions by using Atacama Large Millimeter/submillimeter Array (ALMA) with an angular resolution of about 0$^{\prime\prime}$.3. This resolution corresponds to a linear scale of 400-1600 au, allowing us to resolve individual cores properly. We detected the $^{13}$CH$_3$OH and CH$_2$DOH emission near the continuum peaks in many of these regions. From the two $^{13}$CH$_3$OH lines, we calculated the temperature toward the $^{13}$CH$_3$OH peaks, and confirm that the emission traces hot ($>$100 K) regions. The $N$(CH$_2$DOH)/$N$($^{12}$CH$_3$OH) ratio in the observed high-mass star-forming regions is found to be lower than that in low-mass star-forming regions. We have found no correlation between the $N$(CH$_2$DOH)/$N$($^{13}$CH$_3$OH) or $N$(CH$_2$DOH)/$N$($^{12}$CH$_3$OH) ratios and either temperatures or distance to the sources, and have also found a source-to-source variation in these ratios. Our model calculations predict that the $N$(CH$_2$DOH)/$N$($^{12}$CH$_3$OH) ratio in hot cores depends on the duration of the cold phase; the shorter the cold phase, the lower the deuterium fractionation in the hot cores. We have suggested that the lower $N$(CH$_2$DOH)/$N$($^{12}$CH$_3$OH) ratio in high-mass star-forming regions compared to that in low-mass star-forming regions is due to the shorter duration of the cold phase and that the diversity in the $N$(CH$_2$DOH)/$N$($^{12}$CH$_3$OH) ratio in high-mass star-forming regions is due to the diversity in the length of the cold prestellar phase, and not the time that the objects have been in the hot core phase.

We carry out a search for spatial coincidence between high energy neutrinos detected by the IceCube neutrino detector (using the publicly available 10-year muon track data) and 33 magnetars, including two extragalactic ones. We use the unbinned maximum likelihood method for our analysis. We do not find any such spatial association between any of the galactic magnetars and IceCube-detected neutrinos. Therefore, we conclude that none of the known galactic or extragalactic magnetars contribute to the diffuse neutrino flux observed in IceCube.

Primordial black holes (PBH) accretion in the late Universe can lead to significant mass growth. A larger mass further accelerates the accretion radiation output for PBHs with initial masses greater than one solar mass, potentially leading to a stringent energy-dumping constraint derived from observations of the cosmic microwave background. The energy injected via PBH accretion is capable of ionizing and heating the intergalactic medium (IGM), ultimately affecting the optical depth of cosmic reionization and the 21-cm signal. This work investigates primordial black hole mass growth using the Bondi-Hoyle accretion model and accounts for additional ionization and heating induced by PBHs. We derive stringent PBH abundance limits using an upper limit on optical depth set by Planck 2018 CMB measurements. We find that accretion growth significantly strengthens late-time observational constraints for primordial black holes with initial masses ranging from several solar masses up to $10^4$ solar masses. The PBH fraction of the Universe's unobserved mass content can be constrained to $f_\mathrm{PBH, ini}\sim 10^{-2}$ to $10^{-7}$ in this mass range, and when not accounting for mass evolution our constraints can be weakened by up to one order of magnitude. In addition, we show that PBH mass growth will lead to an observable impact on the predicted hydrogen 21-cm brightness temperature.

Polycyclic aromatic hydrocarbons (PAHs) are key contributors to interstellar infrared emission bands (AIBs). However, current spectral databases for AIB analysis face limitations because of the neglect of anharmonicity in vibrations and of temperature effects, which result from the high computational cost of traditional quantum chemical calculations (QCCs). In this work, we present a machine-learning-based molecular dynamics (MLMD) approach that efficiently computes anharmonic infrared (IR) spectra while accounting for temperature effects. MLMD achieves predictive accuracy comparable to that of QCCs but with significantly reduced computational cost, scaling linearly with the number of atoms in the system. We apply MLMD to calculate the anharmonic spectra of 1\,704 PAHs in the NASA Ames PAH IR Spectroscopic Database with up to 216 carbon atoms, demonstrating its ability to handle large molecular systems. Our results suggest that MLMD can facilitate the creation of extensive molecular spectral databases, advancing AI-assisted analyses of astronomical IR spectra, particularly with upcoming data from the James Webb Space Telescope.

The X-ray quasi-periodic oscillation (QPO) is a remarkable form of variability in systems of compact object accretion. RE J1034+396, harboring the most significant X-ray QPO in active galactic nuclei (AGNs), is the most noteworthy source for in-depth analysis of AGN X-ray QPO properties. A long-term evolution of its QPO has been observed over the course of the observations. However, the short-term variability of its QPO properties remains unexplored within each observation that has long good time intervals (GTIs). We collect 12 XMM-Newton observations of RE J1034+396 with GTIs longer than 60 ks from publicly available data and conduct a detailed wavelet analysis focusing on the short-time modulation of the QPO. The QPO signals are found to undergo amplitude modulation in both the soft and hard bands, with a typical timescale of 17 ks. The soft flux is significantly higher when the hard QPO is present. They are highly correlated, with an average cross-correlation function (CCF) peak coefficient of 0.61 and a lag of approximately 3 ks. This novel finding provides fresh insights into the potential connection between the components of the corona emitting soft and hard X-ray photons. The CCF lag between the soft flux and the hard QPO evolves across the observations, potentially sharing the same origin as the previously observed interconnected evolution between QPO frequency and time lag.

We carry out an imaging survey of six globular clusters (GCs) with a limit magnitude to 22 mag at the 5 sigma level, down to the main sequence stars of the respective cluster, as one of the pilot observing program of the Wide Field Survey Telescope (WFST). This paper present the early results of this survey, where we investigate the tidal characters at the periphery of the clusters NGC 4147, NGC 5024, NGC 5053, NGC 5272, NGC 5904 and NGC 6341. We present the estimated number density of cluster candidates and their spatial distribution. We confirm the presence of tidal arms in NGC 4147 and NGC 5904 and identify several intriguing potential tidal structures in NGC 4147, NGC 5024, NGC 5272, corroborated the elliptical morphology of the periphery of NGC 6341. Our findings underscore the WFST's capability for probing faint structural features in GCs, paving the way for future in-depth studies, especially for the search of the large scale tidal streams associated with the clusters with the future wide field survey.

We present the high-sensitivity and large-scale atomic hydrogen (HI) observations towards lenticular (S0) galaxy NGC 4111 using the Five-hundred-meter Aperture Spherical Radio Telescope (FAST). The column density map shows that NGC4111 and seven other different types of galaxies share a huge HI gas complex. The data also suggest that NGC 4111 is interacting with seven galaxies. Moreover, we identified a rotating gas disk associated with NGC 4111 from the HI complex. Still, the HI disk rotation direction has deviated from its stellar disk about 34.2$^{\circ}$, indicating that the NGC 4111 galaxy is undergoing a transition from a spiral galaxy to an S0 galaxy by the tidal interactions. The obtained dark matter-to-stellar mass ratio of NGC4111 is 3.1$\pm$0.7, which is lower than the average value of the Local Universe, implying that the interactions may strip its dark matter. Our results suggest that in a galaxy group environment, tidal interactions have a significant effect on galaxy features.

We acquired 450 {\mu}m and 850 {\mu}m dust continuum polarization observations toward the inner region of the Central Molecular Zone (CMZ) as part of the B-Fields In Star-Forming Region Observations (BISTRO) survey using the POL-2 polarimeter on the James Clerk Maxwell Telescope. These observations encompassed three dense structures: the 20 km s{^{-1}} cloud (20MC), 50 km s{^{-1}} cloud (50MC), and circumnuclear disk (CND). Our aim is to investigate the magnetic field morphology and strength in the inner region of the CMZ using polarized dust continuum and the Davis-Chandrasekhar-Fermi method. The magnetic field morphology is highly ordered in all three dense regions. The plane-of-sky magnetic field strengths are {\sim}1 mG for the 20MC and the 50MC, and {\sim}2 mG for the CND. We compare the energy contributions of turbulence, gravity, and thermal motion with that of the magnetic field using the plasma {\beta}, mass-to-flux ratio, and Alfvén Mach number. The outcomes reveal the magnetic field stands out as the predominant factor within the inner region of the CMZ. The dominance of the magnetic field may explain the low star-forming rate in the CMZ. We further investigate the dust grain alignment efficiency by exploring the relationship between polarization fraction and total intensity. The results suggest that dust grains are well aligned with the magnetic fields.

In this work, we investigate the influence of interaction between dark matter and dark energy on the growth rate $f$ of matter density perturbations within the framework of an interacting $w$CDM model. The coupling term is assumed to be proportional to the dark energy density, and the growth rate $f$ is parameterized using the form $\Omega_{\rm m}^\gamma$. By considering the effect of this interaction on the growth index $\gamma$ and assuming that $\gamma$ varies with redshift $z$, we derive the $\gamma$ up to its second-order approximation. Our analysis demonstrates that the parameterized form $\Omega_{\rm m}^\gamma$ closely approximates the actual growth rate $f$. We utilize this parameterized form, along with the astronomic observations from Type Ia Supernovae, Baryon Acoustic Oscillations, Cosmic Microwave Background, Hubble parameter $H(z)$ measurements, and the growth rate data from theredshift space distortion (RSD) measurement, to make constraints on the free parameters of the interacting $w$CDM model. Our findings indicate that incorporating RSD measurement data into cosmic background observations can significantly tighten the constraints on the coupling constant, suggesting a preference for a weak interaction between dark matter and dark energy.

We achieved the first VLBI detections of the ground vibrational state ($v=0$) $^{28}$SiO (hereafter, SiO) and $^{29}$SiO masers of the $J=1\rightarrow 0$ rotational transitions, towards the 25 \Msun ~red supergiant (RSG) star, VY Canis Majoris (VY CMa), taking advantage of the high sensitivity of the VLBI Exploration of Radio Astrometry (VERA) telescopes that coordinate with the Nobeyama 45 m telescope. In addition, we successfully detected the SiO $J=1\rightarrow 0$ transition in the $v=3$ state towards VY CMa for the first time with VLBI. The SiO $J=1\rightarrow 0$ maser spot in $v=0$ state was detected in the cross-power spectra taken with the baselines involving the Nobeyama 45-m telescope. The combination of previously reported absolute astrometry and the relative astrometry technique allowed us to derive the location of the SiO $v=0$ maser spot, {(RA, DEC) = ( 7${\rm ^h}$ 22${\rm ^m}$ 58.$^{\rm s}$32, $-$25$^{\circ}$ 46$^{\prime}$ 3.$^{\prime\prime}$4) in J2000 at an absolute positional accuracy of $\sim$100 milliarcseconds (mas). The SiO $v=0$ maser spot is offset by the amount of ($\Delta$RA, $\Delta$DEC)=($-$150, $-$300) (mas) to the southwest of the stellar position, suggesting that the $v = 0$ maser spot is associated with its outflow activity.} This observational study demonstrates that the brightest SiO $v=0$ maser spot is compact (3 mas), producing an extremely high brightness of $\sim$ 10$^7$ K. This indicates that the SiO $v=0$ maser action may originate from strong shocks in the stellar wind emanating from this extreme RSG that leads to its intense mass ejection.

The most complete sample of galactic maser sources and radio stars with trigonometric parallaxes, proper motions and radial velocities measured by the VLBI method has been compiled based on literature data. These sources are associated with young stars located in high mass star forming regions. The rotation parameters of the Galaxy have been determined based on 156 masers with relative parallax errors less than 10\%, located further than 3 kpc from the galactic center. The linear rotation velocity of the Galaxy at the solar distance $R_0$ is $V_0=243.9\pm3.9$ km s$^{-1}$. A very narrow chain of masers 3-4 kpc long, elongated in the $\sim40^\circ$ direction, passing from a segment of the Carina-Sagittarius spiral arm to the Scutum arm, has been studied. A number of authors have hypothesized that this is a possible analogue of the Radcliffe wave. In the present work, no noticeable periodic perturbations of vertical coordinates and velocities were found in this structure. On the other hand, on the diagram ``$\ln(R/R_0)-\theta$'' this chain of masers has the form of a segment of a logarithmic spiral with a pitch angle of $-48^\circ$. Perhaps this chain of masers belongs to a jet extending from the end of the bar, rotating rigidly with the angular velocity of the bar.

Long-term observations of the Galactic center by Fermi and HESS have revealed a novel phenomenon: the high-energy gamma-ray spectrum from the Galactic center exhibits a double power-law structure. In this study, we propose a new explanation for this phenomenon. We suggest that the low-energy (GeV) power-law spectrum originates from interactions between trapped background ``sea" cosmic ray particles and the dense gaseous environment near the Galactic center. In contrast, the bubble-like structure in the high-energy (TeV) spectrum is produced by protons accelerated during active phases of the Galactic center, through the same physical process. Based on this framework, we first calculate the gamma-ray emission generated by cosmic ray protons accelerated in the Galactic center. Then, using a spatially-dependent cosmic ray propagation model, we compute the energy spectrum of background ``sea" cosmic ray protons and their associated diffuse gamma-ray emission in the Galactic center region. The results closely reproduce the observations from Fermi-LAT and HESS, suggesting that their long-term data support this picture: high-energy cosmic rays in the local region originate from nearby cosmic ray sources, while low-energy cosmic rays are a unified contribution from distant cosmic ray sources. We predict that some extended Galactic sources, which remain undetectable in the GeV energy range, may become observable in the TeV range. We hope that future observations will detect more such sources, allowing us to further test and validate our model.

The MeerKAT Fornax Survey (MFS) is a large survey project mapping the HI in the Fornax cluster. Most of the cluster members detected in HI show significant signs of interaction with the intra-cluster medium or other galaxies. The galaxy ESO 358-60 however stands out as its large HI disk appears regular and undisturbed. A possible explanation for this undisturbed disk is that the galaxy is not in Fornax. We analyze the HI distribution within and around ESO 358-60 based on the MFS observations. We visually inspect the low resolution data in order to study the HI disk from the center to its outskirts and look for low column density gas that could reveal recent interactions. We then construct a detailed parameterization of the HI disk by fitting a tilted ring model to the high resolution data cube. We use the fitted rotational velocity to place the galaxy on the baryonic Tully-Fisher relationship. By equating the galaxy's HI and 3.6 $\mu$m fluxes to the thus retrieved baryonic mass, we obtain a redshift independent distance. Our modeling confirms the regularity of the HI disk in ESO 358-60 but also shows that the galaxy contains a significant line of sight warp and contains radial motions, of the order of 10 km s$^{-1}$, that cover the extent of the optical disk. From the modeling we obtain a velocity V$_{\rm flat} = $48.1 $\pm$ 1.4 km s$^{-1}$ for the best fit rotation curve. This leads to a distance from the baryonic Tully-Fisher relation of 9.4 $\pm$ 2.5 Mpc,$\sim$ 10 Mpc less than the distance to the Fornax cluster. This distance not only fits better with V$_{\rm flat}$ but also with the overall HI distribution of low mass galaxies and the fact that the galaxy appears undisturbed and reasonably symmetric. At 9.4 Mpc ESO 358-60 cannot be a member of the Fornax cluster but is a foreground field galaxy.

Context. We present the COMetary dust TAIL Simulator (COMTAILS), a numerical Monte Carlo code to generate images of dust tail brightness from comets and active asteroids in the Solar System. Aims. We describe a numerical code, available to interested users, capable of generating simulated images of dust tail brightness for comparison with observations, to retrieve key dust parameters including size distribution, ejection velocities, and dust loss rates. An optional stellar field can be included in the background allowing for the assessment of stellar extinction by the tail, which can be compared with observational data. Methods. A Monte Carlo procedure was used to obtain the simulated images. The orbital parameters of the targets and their helio-centric positions and velocities were obtained from the JPL Horizons on-line ephemeris system. Results. Earlier versions of this code have been used to characterize the dust environment of various targets. In this study we present recent examples that demonstrate its ability to fit observed images of the long-period comets C/2024 N3 (NEOWISE) and C/2023 A3 (Tsuchinshan-ATLAS). The code is readily applicable to future targets that may be identified for the upcoming European Space Agency Comet Interceptor mission.

The spatial extension of active regions (ARs) of the Sun can vary from one case to the next. This is a problem when studying solar flares with Convolutional Neural Networks (CNNs) as they generally use input images of a fixed size. Different processes can be performed to retrieve a database with homogeneous-sized data, such as resizing. Unfortunately, key features can be lost or distorted during these processes. This can lead to a deterioration of the ability of CNNs to classify flares of different soft X-ray classes, especially those from ARs with complex structures. Our work aims to implement and test a CNN architecture that retains the full features of the original resolution of the input images. We compare the performance of two CNN architectures for solar flare prediction: the first is a traditional CNN with resized input whereas the other implements a spatial pyramid pooling (SPP) layer without any input resizing. Both are trained on the Spaceweather HMI Active Region Patch line-of-sight magnetogram database. We also study two cases of binary classification. In the first case, our model distinguishes ARs producing flares in less than 24h of class greater or equal to C1.0 from ARs producing flares in more than 24h or never; in the second case, it distinguishes ARs producing flares in less than 24h of class greater or equal to M1.0 from the other ARs. Our models implementing an SPP layer outperform the traditional CNN models when predicting flares greater or equal to C1.0 within 24h. However, their performances degrade sharply along the other models studied in this paper, when trained to classify images greater or equal to M1.0 flares. The degradation in SPP models when classifying only images greater or equal to M1.0 flares as positive may be attributed to its success in identifying features that appear in ARs a few hours before the flare, independently of their soft X-ray class.

The conversion of CMB photons to axions (or axion-like particles (ALPs)) can lead to a unique spectral distortion in the temperature and polarization sky which can be explored in upcoming CMB experiments. In this work we have developed a numerical simulation-based technique of photons to ALPs conversion in the galaxy clusters and show for the first time that this physical process can lead to large non-Gaussian signal in the temperature and polarization field, which is impacted by the presence of inhomogeneities and turbulence in the electron density and magnetic field. Our simulation-based technique can simulate the theoretical signal for different scenarios of cluster electron density and magnetic field turbulence and provides testable predictions to discover ALPs from galaxy clusters using spatially non-Gaussian and anisotropic spectral distortion of the microwave sky. We show that the presence of turbulence in the magnetic field and electron density can impact the Gaussian part of the signal captured in terms of the angular power spectra of the signal by more than an order of magnitude. Also, the presence of turbulence in different clusters will lead the temperature and polarization fluctuations around the cluster region to have varying non-Gaussian distribution, with peaks and tails different from the Gaussian statistics of the CMB anisotropy. This new numerical technique has made it possible to calculate also the non-Gaussian signals and can be used in future CMB analysis in synergy with X-ray and radio observations to unveil ALPs coupling with photons in the currently unexplored ranges, for the masses between about $10^{-14}$ eV--$10^{-11}$ eV.

Radio galaxies can be classified into two types, FR I and FR II, depending on their morphology. So far, the reasons for the different behaviour of FR I and FR II in observations have not been clarified. While the Unified Model suggests that the viewing angle and the obscuring effect of the dust ring are the main reasons for the difference in the classification of FR I and FR II radio galaxies, it has been found that the accretion rate and the accretion pattern of the central engine may play a more crucial role. In order to investigate the physical properties of these sources, the cloudy program was used to simulate the 3C 348 radio source outlook ionisation model, and it was found that its optical emission in the nuclear region is significantly lower than the theoretical prediction, which suggests the existence of an obscuration effect, which was later further proved by the spectral decomposition method. And using the thermometric photometry-jet relationship, it is found that the accretion rate in its nuclear region is much lower than the accretion rate inverted from the total jet power, indicating that its accretion mode is in the critical stage of the transition from the standard thin disc to the ADAF. Combined with its Bondi accretion rate, the fitted energy spectrum of the nuclear region shows that the evolution of its jet power is controlled by the change of the central accretion engine.

We present Keck High Resolution Echelle Spectrometer (HIRES) observations and model atmosphere analysis for two nearby, cool, helium-dominated atmosphere white dwarfs that have been polluted by accretion: WD J1927-0355 and WD J2141-3300. Detected elements common to both white dwarfs are Mg, Ca, Ti, Cr, Fe, and Ni, with additional detections of Na, Al, Si and Sr in WD J2141-3300. We present an approach for inferring the composition of the accreted material, by adopting a physically motivated model in which the mass accretion rate decays exponentially with time, which provides constraints on the time since the start of the accretion event. The accretion events were most likely to have began at least 1 Myr ago, however the characteristic disc lifetime could not be constrained due to degeneracies. Both white dwarfs were found to have accreted bulk planetary material with compositions similar to that of both bulk Earth and chondritic meteorites. The parent bodies causing pollution in both cases were inferred to be the mass of a small moon or dwarf planet.

Comets are the most pristine planetesimals left from the formation of the Solar System. They carry unique information on the materials and the physical processes which led to the presence of planets and moons. Many important questions about cometary physics, such as origin, constituents and mechanism of cometary activity, remain unanswered. The next perihelion of comet 1P/Halley, in 2061, is an excellent opportunity to revisit this object of outstanding scientific and cultural relevance. In 1986, during its latest approach to the Sun, several flyby targeted Halley's comet to observe its nucleus and shed light on its properties, origin, and evolution. However, due to its retrograde orbit and high ecliptic inclination, the quality of data was limited by the large relative velocity and short time spent by the spacecraft inside the coma of the comet. A rendezvous mission like ESA/Rosetta would overcome such limitations, but the trajectory design is extremely challenging due to the shortcomings of current propulsion technology. Given the considerable lead times of spacecraft development and the long duration of the interplanetary transfer required to reach the comet, it is imperative to start mission planning several decades in advance. This study presents a low-thrust rendezvous strategy to reach the comet before the phase of intense activity during the close approach to the Sun. The trajectory design combines a gravity-assist maneuver with electric propulsion arcs to maximize scientific payload mass while constraining transfer duration. A propulsive plane change maneuver would be prohibitive. To keep the propellant budget within reasonable limits, most of the plane change maneuver is achieved via either a Jupiter or a Saturn flyby. The interplanetary low-thrust gravity-assisted trajectory design strategy is described, followed by the presentation of multiple proof-of-concept solutions.

Dust grains embedded in gas flow give rise to a class of hydrodynamic instabilities that can occur whenever there exists a relative velocity between gas and dust. These instabilities have predominantly been studied for single grain sizes, for which a strong interaction can be found between drifting dust and a travelling gas wave, leading to fast-growing perturbations (growth rates $\propto \sqrt{\mu}$) even at small dust-to-gas ratios $\mu$. They are called resonant drag instabilities. We focus on the acoustic resonant drag instability, which is potentially important in AGB star outflows, around supernova remnants and star clusters in starburst galaxies. We study the acoustic resonant drag instability, taking into account a continuous spectrum of grain sizes, to determine whether it survives in the polydisperse regime and how the resulting growth rates compare to the monodisperse case. We solve the linear equations for a polydisperse fluid for the acoustic drag instability, focusing on small dust-to-gas ratios. Size distributions of realistic width turn the fast-growing perturbations $\propto \sqrt{\mu}$ of the monodisperse limit into slower growing perturbations $\propto \mu$ due to the fact that the backreaction on the gas involves an integration over the resonance. Furthermore, the large wave numbers that grow fastest in the monodisperse regime are stabilized by a size distribution, severely limiting the growth rates in the polydisperse regime. The acoustic resonant drag instability turns from a singularly perturbed problem in $\mu$ in the monodisperse limit into a regular perturbation for a sufficiently wide size distribution. It can still grow exponentially in the polydisperse regime, but at a slower pace compared to the single size case.

This chapter provides a brief introduction to the chemical composition of the Sun. The focus of the chapter is on results obtained from the physical analysis of the solar photosphere. Data obtained from meteorites, solar wind and corona measurements, as well as helioseismology, and solar neutrinos are briefly reviewed. The elemental and isotopic composition of the solar system is derived by combining the solar and meteoritic data. The cosmochemical and astronomical abundance scales are described. The results of the determinations of the protosolar chemical composition, as well as the initial and present-day mass fractions of hydrogen, helium, and metals (X, Y, Z) for the solar system are presented in extensive tables. All tables are also available in machine-readable form via Zenodo this https URL

The new black hole transient Swift J1727.8--1613 exhibited a series of X-ray flares during its 2023 outburst extensively observed with Insight-HXMT. We analyze the spectra of the flaring period using a series of models consisting of a multi-color disk and several different non-thermal components, and several consistent conclusions are obtained among these models. First, Swift J1727.8--1613 was in the transition process from the hard intermediate state (HIMS) to the very high state (VHS) during the first flaring period (MJD 60197--60204), and afterwards it exhibited typical VHS parameter characteristics, such as high temperature of the disk inner radius and a steep power-law spectrum with a photon index of 2.6. Second, the flares in the VHS are characterized by a rapid increase in the flux of accretion disk, accompanied by a simultaneous rapid expansion of the inner radius, which could be apparent if the accretion disk hardening factor varies significantly. The strong power-law component during the VHS is likely produced by synchrotron self-Compton process in the relativistic jets, in agreement with the observed weak reflection component and lack of correlation with the disk component.

We determined phase curves for 301,272 asteroids in the orange filter and 280,953 in the cyan filter from the latest ATLAS Solar System Catalog V2 (SSCAT-2). Among them, 3,345 and 492 asteroids in the orange and cyan filters, respectively, have uncertainties below 15%. Our simple model, which considers only the apparition effect, showed good consistency with more sophisticated methods requiring much less computational time. Database cross-matching allowed us to analyze G1 and G2 distributions according to taxonomy. We conducted two-dimensional Kolmogorov-Smirnov tests to investigate two distinct aspects: similarities in paired G1, G2 distributions across different taxa and wavelength dependency within the same taxa. When comparing different taxa, we couldn't reject the null hypothesis for 11% of the orange sample and 31% of the cyan sample, indicating more disparities in the orange filter. For wavelength dependency, paired distributions of G1, G2 (o) vs. G1, G2 (c) showed statistically significant differences across all complexes, except for the A class. Our analysis suggests that while phase coloring behaviors are observed without a clear preference for reddening or bluening at phase angles below 5 degrees, reddening predominates in the 10 - 30 degrees range. We also observed smaller uncertainties in G2 than in G1. Simulations showed that G2 is less sensitive to lack of data at small phase angles. This is related to the definition of the H,G1,G2 function, where G1 contributes more to the opposition effect and G2 the linear part of the phase curve. Our catalog-independent algorithms are adaptable to new data sets, including future LSST data.

The IRAC camera on the Spitzer Space Telescope observed 2175 Near Earth Objects (NEOs) during its Warm Mission phase, primarily in three large surveys, and also in a small number of a dedicated projects. In this paper we present the final reprocessing of the NEO data and determine fluxes at 3.6 microns (where available) and 4.5 microns. The observing windows range from minutes to nearly ten hours, which means that for 39 NEOs we observe a complete lightcurve, and for these objects we present period and amplitude estimates and derive minimum cohesive strengths for the objects with well-determined periods. For an additional 128 objects we detect a significant fraction of a complete lightcurve, and present estimated lower limits to their rotation periods. This paper presents the final and definitive Spitzer/IRAC NEO flux catalog.

We formulate the statistics of peaks of non-Gaussian random fields and implement it to study the sphericity of peaks. For non-Gaussianity of the local type, we present a general formalism valid regardless of how large the deviation from Gaussian statistics is. For general types of non-Gaussianity, we provide a framework that applies to any system with a given power spectrum and the corresponding bispectrum in the regime in which contributions from higher-order correlators can be neglected. We present an explicit expression for the most probable values of the sphericity parameters, including the effect of non-Gaussianity on the profile. We show that the effects of small perturbative non-Gaussianity on the sphericity parameters are negligible, as they are even smaller than the subleading Gaussian corrections. In contrast, we find that large non-Gaussianity can significantly distort the peak configurations, making them much less spherical.

We report results from an $AstroSat$ Target-of-Opportunity (ToO) observation of 4U 1626$-$67, performed on 2023 May 18, soon after the discovery of torque reversal to spin-down in the source. The X-ray emission exhibited significant dependence on both energy and torque state. This work highlights the comparison of timing features of 4U 1626$-$67 with a previous $AstroSat$ observation from 2018, when the neutron star was in the spin-up state. The power density spectrum (PDS) of the 2023 observation comprised a sharp peak corresponding to $\nu_{\rm NS}\sim$130 mHz X-ray pulsations along with a prominent quasi-periodic oscillation (QPO) feature at $\nu_{\rm QPO}\sim$46 mHz with $\sim$20\% rms amplitude, which was positively correlated with energy. We also report the detection of sidebands to QPO occurring at a beat frequency ($\nu_{\rm NS}-\nu_{\rm QPO}$) of $\sim$83 mHz with $\sim$8\% rms amplitude, having $>3\sigma$ detection significance. Additionally, we utilized $Nuclear ~Spectroscopic ~Telescope ~ARray$ ($NuSTAR$) observations from the same torque state (2023 May-July) to analogize the presence and energy dependence of sidebands. The source retains timing properties in this spin-down torque state, similar to those seen in the previous spin-down phase. In sharp contrast, PDS from the 2018 observation was dominated by red noise, an absence of QPOs and a broadening in the wings of the pulse frequency peak, indicating a coupling between periodic and low-frequency aperiodic variability. Furthermore, we detected the known cyclotron resonance scattering feature (CRSF) at 37 keV in the Large Area X-ray Proportional Counter (LAXPC) spectrum. We explore various mechanisms that could possibly explain the presence of QPOs exclusively during the spin-down state.

Coronal oscillations offer insight into energy transport and driving in the solar atmosphere. Knowing its polarisation state helps constrain a wave's displacement and velocity amplitude, improving estimates of wave energy flux and deposition rate. We demonstrate a method to combine imaging and spectral data to infer the polarisation of a coronal loop's standing kink wave, without the need for multiple instruments or multiple lines of sight. We use the unique capabilities of the Coronal Multi-channel Polarimeter (CoMP) to observe the standing kink mode of an off-limb coronal loop perturbed by an eruption. The full off-disk corona is observed using the 1074 nm Fe XIII spectral line, providing Doppler velocity, intensity and line width. By tracking the oscillatory motion of a loop apex in a time-distance map, we extract the line-of-sight (Doppler) velocity of the inhomogeneity as it sways and compare it with the derivative of its plane-of-sky displacement. This analysis provides the loop's velocity in two perpendicular planes as it oscillates with a period of $8.9^{+0.5}_{-0.5}$ minutes. Through detailed analysis of the phase relation between the transverse velocities we infer the kink oscillation to be horizontally polarised, oscillating in a plane tilted $-13.6^{+2.9}_{-3.0}$ degrees away from the plane of sky. The line widths show a periodic enhancement during the kink oscillation, exhibiting both the kink period and its double. This study is the first to combine direct imaging and spectral data to infer the polarisation of a coronal loop oscillation from a single viewpoint.

Understanding galactic magnetic fields is essential for interpreting feedback processes in galaxies. Despite their importance, the exact structure of these fields, particularly in galactic halos, remains unclear. Accurate descriptions are crucial for understanding the interaction between star formation and halo magnetisation. By systematically analysing the polarisation patterns in halos of nearby galaxies, we aim to deepen the understanding of the interplay between galactic magnetic fields and star formation processes. We provide an analytical description of the observed X-shaped halos. Based on radio polarimetry data, we classify the polarisation patterns of a sample of edge-on galaxies, by using a newly introduced three-class system: disc dominated, small-scale, and X-shaped. We then fit X-shaped patterns to the polarisation data for galaxies classified as X-shaped and explore links between the polarisation patterns and other physical properties of these galaxies. The classification process shows that 11 out of 18 analysed galaxies display an X-shaped polarisation pattern. Galaxies classified as disc dominated seem less efficient at forming stars than expected for their stellar mass and rotate faster than galaxies with similarly sized HI-discs. X-shape modelling reveals that the polarisation patterns are best fitted by a constant-angle model, and we observe a correlation between the X-shape opening angle and star formation rate surface density indicating the interplay between the star formation in the disc and the magnetisation of the galactic halo. The analysis of polarisation patterns in nearby galaxies reveals that most exhibit an X-shaped configuration, indicating a common magnetic field structure in galactic halos. The introduced models capture the X-shaped morphology and reveal the link between the X-shape's opening angle and star formation rate surface density.

PSR J0514$-$4002A is a binary millisecond pulsar located in the globular cluster NGC 1851. The pulsar has a spin period of 4.99 ms, an orbital period of 18.8 days, and is in a very eccentric ($e = 0.89$) orbit around a massive companion. In this work, we present the updated timing analysis of this system, obtained with an additional 1 yr of monthly observations using the Giant Metrewave Radio Telescope and 2.5 yrs of observations using the MeerKAT telescope. This has allowed for a precise measurement of the proper motion of the system, implying a transverse velocity of $30\,\pm\,7\,\mathrm{km}\,\mathrm{s}^{-1}$ relative to the cluster. This is smaller than the cluster's escape velocity and consistent with the pulsar's association to NGC 1851. We have confirmed a large second spin frequency derivative and large associated jerk, which has increased the spin frequency derivative by a factor of 27 since the mid-2000s. The third spin frequency derivative showed that the strength of this jerk has increased by $\sim 65\%$ in the same time period. We take the effect of the changing acceleration into account and this allows for much improved estimates of the orbital period derivative. The large and fast-increasing jerk implies the presence of a third body in the vicinity of the pulsar (no counterpart is detectable within distance limit in HST images). Based on our measured parameters, we constrain the mass, distance and orbital parameters for this third body. The induced tidal contributions to the post-Keplerian parameters are small, and the precise measurement of these parameters allowed us to obtain precise mass measurements for the system: $M_\mathrm{tot} = 2.4734(3)$ M$_{\odot}$, $M_\mathrm{p} = 1.39(3)$ M$_{\odot}$, $M_\mathrm{c} = 1.08(3)$ M$_{\odot}$. This indicates that the pulsar's companion is a massive white dwarf and resolves the earlier ambiguity regarding its nature.

We investigate the alignment between the angular momenta of galaxy groups and the spines of their associated cosmic filaments. Our results demonstrate a significant tendency for these two orientations to be perpendicular, indicating that the rotation of a galaxy group does not originate from the spin of cosmic filaments. Instead, it is driven by the orbital angular momentum contributed by member galaxies as they accrete along the direction of the filament spines. Moreover, the strength of this perpendicular alignment signal varies with the richness of the galaxy groups, with the most pronounced alignment observed among the wealthiest groups. This pronounced alignment is largely due to the more coherent spatial distribution of member galaxies in richer groups relative to the filament spines. Our study provides valuable insights into the mechanisms of angular momentum acquisition in galaxy groups from an observational standpoint.

The Axelrod approximation is widely used in astrophysical modelling codes to evaluate electron-impact excitation effective collision strengths for forbidden transitions. Approximate methods such as this are a necessity for many heavy elements with open shells where collisional data is either non existent or sparse as the use of more robust methods prove prohibitively expensive. Atomic data for such forbidden transitions are essential for producing full collisional radiative models that do not assume Local-Thermodynamic-Equilibrium (LTE). In this short work we repeat the optimization of the simple Axelrod formula for a large number of $R$-matrix data sets, ranging from Fe and Ni to the first r-process peak elements of Sr, Y and Zr, to higher Z systems Te, W, Pt and Au. We show that the approximate treatment of forbidden transitions can be a significant source of inaccuracy in such collisional radiative models. We find a large variance of the optimized coefficients for differing systems and charge states, although some general trends can be seen based on the orbital structure of the ground-state-configurations. These trends could potentially inform better estimates for future calculations for elements where $R$-matrix data is not available.

CARMENES stands for Calar Alto high-Resolution search for M dwarfs with Exoearths with Near-infrared and optical Échelle Spectrographs. CARMENES took six years from a concept to the start of operations, and a couple more years of initial data collection until the first science publication, but now is revolutionising our knowledge on exoplanets and their stars in our immediate vicinity. Here we describe what CARMENES is: (i) an ultra-stabilised two-channel spectrograph at an almost dedicated 3.5 m telescope in southern Spain that covers in high spectral resolution and without big gaps from 0.52 mum to 1.71 mum; (ii) a science project aimed at comprehensively searching for and studying planetary systems with nearby, bright, M-dwarf hosts, but that also investigates transiting planets around other stars; and (iii) the German-Spanish consortium that designed and built the instrument and that has operated it under guaranteed and legacy time observations.

The recent discovery of large-amplitude pulsations in faint blue stars (BLAPs) provides both challenges for stellar pulsation theory and opportunities to explore the late evolution of low-mass stars. This paper explores the radial-mode stability of stars across parameter space occupied by BLAPs. Models are constructed for homogeneous stellar envelopes and are agnostic of evolution. Linear non-adiabatic models demonstrate the major requirement for pulsations to be enrichment of iron and nickel in the driving zone to a few times the solar abundance. There is no constraint on mass. Non-linear models demonstrate that BLAP pulsations will be of large amplitude and will show strong shocks at minimum radius. A variety of light-curve shapes are found across the BLAP instability strip, accounting for the variety observed. Linearised period relations are derived from the non-linear models. The phase of maximum luminosity relative to minimum radius is correlated with effective temperature ($T_{\rm eff}$), preceding for cool stars and following for hot stars, and split if close to minimum radius. In both linear and non-linear cases, most models pulsate in the fundamental mode (F). First-overtone (1H) pulsations are excited on the low luminosity blue side of the instability region and become more prevalent at higher mass. The period ratio $P_{\rm 1H}/P_{\rm F}=0.81$ contrasts with the classical Cepheid value (0.70 - 0.75). The transition from F to 1H mode pulsations follows a period-mass relation; the F-mode pulsators adjacent to the transition show a reverse shock. At high $T_{\rm eff}$ some non-linear models show unstable overtone modes up to 5H and multi-mode behaviour. The linear and non-linear analyses concur on the red-edge of the instability region, but the non-linear blue edge is hotter.

Axions and axion-like particles (ALPs) have gained substantial attention as potential candidates for cold dark matter. The ALP field can exhibit fluctuations stemming from initial conditions. These initial field fluctuations hold the potential to give rise to gravitationally bound configurations known as axion miniclusters (AMC). While this proposition is widely accepted in the post-inflationary Peccei-Quinn symmetry-breaking scenario, uncertainties persist regarding the pre-inflationary scenario, where the effects of the initial field fluctuations may be suppressed by inflation. In this study, we investigate the influence of adiabatic temperature fluctuations of the primordial plasma on the evolution of axion density perturbations and their power spectrum, aiming to explore the possibility of AMC formation in the pre-inflationary scenario. Our analysis reveals that the impact of adiabatic temperature fluctuations becomes significant when $f_{\rm a} / H_{\rm inf} \gtrsim 1.25 \times 10^4$ and surpasses that of quantum fluctuations by up to five orders of magnitude on large scales. This emphasizes the possibility of also forming AMC within the pre-inflationary scenario. Consequently, a detection of AMC would not reliably differentiate between the pre- and post-inflationary origin of axions.

The James Webb Space Telescope has detected massive black holes (BHs) with masses of $\sim 10^{6-8}~M_\odot$ within the first billion years of the universe. One of the remarkable findings is the identification of "Little Red Dots" (LRDs), a unique class of active galactic nuclei (AGNs) with distinct characteristics representing a key phase in the formation and growth of early BHs. Here, we analyze the occurrence rate of LRDs, which emerge around redshifts $z \sim 6-8$ and sharply decline at $z < 4$. We find that this trend follows a log-normal distribution, commonly observed in phenomena driven by stochastic and random factors. We propose a hypothesis that the first one or two AGN events associated with newly-formed seed BHs are observed as LRDs and their unique features fade in the subsequent episodes. This naturally explains the cosmic evolution of AGN abundance over $0 < z < 5$, which follows $\propto (1+z)^{-5/2}$ due to the cumulative effect of recurring AGN activity. The unique characteristics of LRDs are likely linked to the dense gas environments around the seed BHs, which create strong absorption features in the broad-line emission and enable super-Eddington accretion bursts, ultimately yielding the observed overmassive nature of BHs compared to the local relationship.

Fundamental questions about the physics responsible for fragmenting molecular parsec-scale clumps into cores of ~1000 au are still open, that only a statistically significant investigation with ALMA is able to address: what are the dominant agents that determine the core demographics, mass, and spatial distribution as a function of the physical properties of the hosting clumps, their evolutionary stage and the different Galactic environments in which they reside? To what extent extent is fragmentation driven by clumps dynamics or mass transport in filaments? With ALMAGAL we observed the 1.38 mm continuum and lines toward more than 1000 dense clumps in our Galaxy, with M>500M_sun, surface density > 0.1 g/cm2 and d<7.5 kpc. The ACA and two 12-m array setups were used to deliver a minimum resolution of ~1000 au over the entire sample distance range. The sample covers all evolutionary stages from infrared dark clouds (IRDCs) to HII regions from the tip of the Galactic bar to the outskirts of the Galaxy. The spectral setup includes several molecular lines to trace the multiscale physics and dynamics of gas, notably CH3CN, H2CO, SiO, CH3OH, DCN, HC3N, SO etc. We present an initial overview of the observations and the early science product and results, with a first characterization of the morphological properties of the continuum emission. We use "perimeter-versus-area" and convex hull-versus-area metrics to classify the different morphologies. More extended and morphologically complex shapes are found toward clumps that are relatively more evolved and have higher surface densities.

Several space missions are proposed or planned for the coming two decades dedicated or including mid- to high-resolution spectropolarimetry on a wide UV band. This includes the European instrument Pollux for the NASA HWO flagship mission, the NASA SMEX candidate Polstar, and the French nanosatellite demonstrator CASSTOR. We are developing UV polarimeters for these missions thanks to a R&D program funded by CNES. For the mid- and near-UV, i.e. above 120 nm, birefringent material (MgF2) can be used to produce a polarimeter. This is the baseline for Polstar, CASSTOR, and the MUV and NUV channels of Pollux. Prototypes have been built and tested with excellent results, and further tests are ongoing to fully characterize them. For the FUV channel of Pollux however, it is not possible to use this technology and we have instead studied a design based on mirrors only. We will present the various missions and instruments, their technical challenges, as well as the R&D work performed on UV polarimeters and the proposed design solutions.

The ALMAGAL Large Program has observed 1017 high-mass star-forming regions distributed throughout the Galaxy, sampling different evolutionary stages and environmental conditions. In this work, we present the acquisition and processing of the ALMAGAL data. The main goal is to set up a robust pipeline that generates science-ready products, with a good and uniform quality across the whole sample. ALMAGAL observations were performed with the Atacama Large Millimeter/submillimeter Array (ALMA). Each field was observed in three different telescope arrays, being sensitive to spatial scales ranging from 1000 au up to 0.1 pc. The spectral setup allows sensitive imaging of the continuum emission at 219 GHz, and it covers multiple molecular spectral lines observed in four different spectral windows that span about 4 GHz in frequency coverage. We have designed a Python-based processing workflow to calibrate and image these observational data. This ALMAGAL pipeline includes an improved continuum determination, suited for line-rich sources; an automatic self-calibration process that improves the dynamical range of the final images; and the combination of data from different telescope arrays to produce science-ready, fully combined images. The fully combined products have spatial resolutions in the range 800-2000 au, and mass sensitivities in the range 0.02-0.07 Mo. We also present a first analysis of the spectral line information included in the ALMAGAL setup, and its potential for future scientific studies. As an example, specific spectral lines at 1000 au scales resolve the presence of multiple outflows in clusters and will help us to search for disk candidates around massive protostars. Moreover, the broad frequency bands provide information on the chemical richness of the different cluster members, which can be used to study the chemical evolution during the formation process of star clusters.

We present new upper limits on the 21-cm signal power spectrum from the Epoch of Reionization (EoR), at redshifts $z \approx 10.1, 9.1, \text{ and } 8.3$, based on reprocessed observations from the Low-Frequency Array (LOFAR). The analysis incorporates significant enhancements in calibration methods, sky model subtraction, radio-frequency interference (RFI) mitigation, and an improved signal separation technique using machine learning to develop a physically motivated covariance model for the 21-cm signal. These advancements have markedly reduced previously observed excess power due to residual systematics, bringing the measurements closer to the theoretical thermal noise limit across the entire $k$-space. Using comparable observational data, we achieve a 2 to 4-fold improvement over our previous LOFAR limits, with best upper limits of $\Delta_{21}^2 < (68.7\,\mathrm{mK})^2$ at $k = 0.076\,h\,\mathrm{cMpc}^{-1}$, $\Delta_{21}^2 < (54.3\,\mathrm{mK})^2$ at $k = 0.076\,h\,\mathrm{cMpc}^{-1}$ and $\Delta_{21}^2 < (65.5\,\mathrm{mK})^2$ at $k = 0.083\,h\,\mathrm{cMpc}^{-1}$ at redshifts $z \approx 10.1, 9.1$, and $8.3$, respectively. These new multi-redshift upper limits provide new constraints that can be used to refine our understanding of the astrophysical processes during the EoR. Comprehensive validation tests, including signal injection, were performed to ensure the robustness of our methods. The remaining excess power is attributed to residual foreground emissions from distant sources, beam model inaccuracies, and low-level RFI. We discuss ongoing and future improvements to the data processing pipeline aimed at further reducing these residuals, thereby enhancing the sensitivity of LOFAR observations in the quest to detect the 21-cm signal from the EoR.

A planet's albedo is a fundamental property that sets its energy budget by dictating the fraction of incident radiation absorbed versus reflected back to space. Generally, optical eclipse observations have revealed the majority of hot, giant planets to have low albedos, indicating dayside atmospheres dominated by absorption instead of reflection. However, there are several exceptions to this rule, including the ultra-hot-Neptune LTT 9779b, which have been found to have high geometric albedos. We observed four eclipses of LTT 9779b with the G280 grism of the Hubble Space Telescope's WFC3 UVIS mode; targeting the scattering signatures of the cloud condensate species causing the planet's elevated reflectivity. However, we do not definitively detect the planet's eclipse in our observations, with injection-recovery tests yielding a 3-$\sigma$ upper limit of 113 ppm on the eclipse depth of LTT 9779b in the 0.2-0.8$\mu$m waveband. We create reflectance spectrum grids for LTT 9779b's dayside using VIRGA/PICASO and compare to our UVIS limit, as well as previously published CHEOPS and TESS eclipse photometry. We find that silicate condensates are best able to explain LTT 9779b's highly-reflective dayside. Our forward model grids only enable weak constraints on vertical mixing efficiency, and suggest that, regardless of their particular composition, the clouds are likely composed of smaller and more reflective particles. Our work facilitates a deeper understanding of the reflectance properties of LTT 9779b as well as the UVIS spectroscopic mode itself, which will remain the community's primary access to UV wavelengths until next-generation telescopes like the Habitable Worlds Observatory.

We study the intrinsic and observable shapes of approximately 700 star-forming galaxies with stellar masses $10^8 - 10^{11}$ M$_\odot$ from the FIREbox simulation at $z=0$. We calculate intrinsic axis ratios using inertia tensors weighted by: All Stars, Young Stars, and Luminosity-weighted Stars. Young Stars, in particular, are arranged in systematically different 3D configurations as a function of galaxy stellar mass, with spheroidal, elongated, and disky shapes dominant at stellar masses of $10^{8.5}$ M$_\odot$, $10^{9.5}$ M$_\odot$, and $10^{10.5}$ M$_\odot$, respectively. We construct mock images for each galaxy and show that projected short-to-long axis ratios, $q$, inferred from 2D Sérsic fits are most closely related to Luminosity-weighted tensor shapes and least resemble the All Stars shapes. This suggests observed 2D shape distributions should not be compared to predictions based on 3D stellar mass shapes. We construct a sample of mock images projected in random orientations and compare them to observed axis ratio distributions from the GAMA survey. For galaxies with stellar masses $10^{10} - 10^{11}$ M$_\odot$, we reproduce axis ratios comparable to the thinnest observed in real galaxies ($q \sim 0.1$), suggesting this model is capable of making thin disk galaxies at Milky Way scale. However, at masses below $10^{10}$ M$_\odot$, we produce an insufficient population of galaxies with observed $q<0.4$ and none with $q<0.2$, suggesting that FIREbox does not produce enough low-mass disk galaxies. Future observational and theoretical programs aimed at understanding low-mass disk fractions will provide crucial tests of galaxy formation models.

The origin of chondrules, and the chondritic sedimentary rocks that dominate the meteoritic record, is a long-standing problem in planetary science. Here, we develop a physical model for the formation of chondritic mixtures as an outcome of vaporizing collisions between planetesimals that were dynamically excited by the growth and migration of planets. We present calculations of nebular shock waves generated by impact vapor plumes and focus on aspects of the plume interaction with the nebular gas and dust that have been neglected in previous studies of impact ejecta. We find that, when water dominates the vapor, the plumes are relatively cool. However, the plume expansion is supersonic and can drive strong shock waves in the dusty nebular gas. Portions of these nebular shock fronts initially melt nebular dust, forming chondrules that are coupled to the moving front. As the shock front expands and cools, the chondrules solidify while the shock front entrains additional dust. Eventually, the plume expansion stalls and then hydrodynamically collapses, turbulently mixing variably processed dust and size-sorted chondrules. For probable impact parameters and nebular conditions during giant planet growth and migration, the impact-generated mixtures have characteristics that span the range observed in chondritic meteorites, providing an environment for rapid formation of chondritic assemblages after chondrule formation. Our impact vapor and nebular shocks (IVANS) model links chondrule formation to the overall context of planet formation and provides a framework for interpreting the detailed chronological and geochemical record contained in chondritic meteorites.

The mechanisms behind the fragmentation of high-mass dense clumps into compact star-forming cores are fundamental topics in current astrophysical research. The ALMAGAL survey provides the opportunity to study this process at an unprecedented level of detail and statistical significance, featuring high-angular resolution $1.38$ mm ALMA observations of $1013$ massive dense clumps at various Galactic locations. These clumps cover a wide range of distances, masses, surface densities, and evolutionary stages. Here, we present the catalog of compact sources obtained with the CuTEx algorithm from continuum images of the full ALMAGAL clump sample combining ACA-$7$m and $12$m ALMA arrays, reaching a uniform high median spatial resolution of $\sim1400$ au. We discuss the fragmentation properties and the estimated physical parameters of the core population. The ALMAGAL compact source catalog includes $6348$ cores detected in $844$ clumps ($83\%$ of the total), with a number of cores per clump between $1$ and $49$ (median of $5$). The estimated core diameters are mostly within $\sim800-3000$ au (median of $1700$ au). We obtained core masses from $0.002$ to $345\,\mathrm{M_{\odot}}$. We evaluated the variation in the core mass function (CMF) with evolution as traced by the clump $L/M$, finding a clear, robust shift and change in slope among CMFs within subsamples at different stages. This finding suggests that the CMF shape is not constant throughout the star formation process, but rather it builds (and flattens) with evolution, with higher core masses reached at later stages. We found that all cores within a clump grow in mass on average with evolution, and the number of cores increases with the core masses. Our results favor a clump-fed scenario for high-mass star formation, in which cores form as low-mass seeds, and then gain mass while further fragmentation occurs in the clump.

Recently, the James Webb Space Telescope (JWST) has found early galaxies producing photons from more efficient ionization than previously assumed. This may suggest a reionization process with a larger reionization optical depth, $\tau_{\rm reio}$, in some mild disagreement with that inferred from measurements of cosmic microwave background (CMB). Intriguingly, the CMB would prefer larger values of $\tau_{\rm reio}$, more consistent with the recent JWST hint, if the large-scale measurements (i.e. $\ell <30$) of E-mode polarization are removed. In addition, $\tau_{\rm reio}$ has an indirect correlation with today's Hubble constant $H_0$ in $\Lambda$CDM. Motivated by these interesting observations, we investigate and reveal the underlying mechanism for this correlation, using the CMB dataset without the low-$\ell$ polarization data as a proxy for a potential cosmology with a larger $\tau_{\rm reio}$. We further explore how this correlation may impact the Hubble tension between early and late universe measurements of $H_0$, in $\Lambda$CDM as well as two proposals to alleviate the Hubble tension: the dark radiation (DR) and early dark energy (EDE) models. We find that the Hubble tension gets further reduced mildly for almost all cases due to the larger $\tau_{\rm reio}$ and its positive correlation with $H_0$, with either the Baryon Acoustic Oscillations (BAO) data before those from the Dark Energy Spectroscopic Instrument (DESI) or the DESI data.

We describe observations and physical characteristics of Earth-crossing asteroid 2024 YR$_4$, discovered on 2024 December 27 by the Asteroid Terrestrial-impact Last Alert System. The asteroid has semi-major axis, $a$ = 2.52 au, eccentricity, $e$ = 0.66, inclination $i$ = 3.41$^{\circ}$, and a $\sim$0.003 au Earth minimum orbit intersection distance. We obtained g, r, i, and Z imaging with the Gemini South/Gemini Multi-Object Spectrograph on 2025 February 7. We measured a g-i spectral slope of 13$\pm$3 $\%$/100 nm, and color indices g-r = 0.70$\pm$0.10, r-i = 0.25$\pm$0.06, i-Z = -0.27$\pm$0.10. 2024 YR$_4$ has a spectrum that best matches R-type and Sa-type asteroids and a diameter of $\sim$30-65 m using our measured absolute magnitude of 23.9$\pm$0.3, and assuming an albedo of 0.15-0.4. The lightcurve of 2024 YR$_4$ shows $\sim$0.4 mag variations with a rotation period of $\sim$1170 s. We use photometry of 2024 YR$_4$ from Gemini and other sources taken between 2024 December to 2025 February to determine the asteroid's spin vector and shape, finding that it has an oblate, $\sim$3:1 a:c axial ratio and a pole direction of $\lambda$, $\beta$ = $\sim$42$^{\circ}$, $\sim$-25$^{\circ}$. Finally, we compare the orbital elements of 2024 YR$_4$ with the NEO population model and find that its most likely sources are resonances between the inner and central Main Belt.

Coupled dark sector models have gained significant attention, motivated by recent advances in cosmology and the pressing need to address unresolved puzzles. In this work, we study coupled scalar dark sector models inspired by ultraviolet-complete frameworks such as supergravity and string theory. These models involve scalar couplings arising either from their kinetic terms, through a non-trivial field space metric, or from their scalar potential. We demonstrate how these couplings can be elegantly formulated in terms of an interacting vector, a standard tool in coupled dark sector studies, and analyse their distinct cosmological effects using a dynamical systems approach. Using this framework, we further investigate an axio-dilaton system recently explored in the literature, where the dilaton also couples to baryons. Intriguingly, we show that certain kinetic and potential interactions may mimic one another or even cancel out, making them observationally indistinguishable. If such a distinction becomes possible through observational constraints, it could provide valuable insights into the underlying field space metric and its connection to fundamental physics.

We investigate the indirect detection search of the two-body decay of dark matter particles into final states containing a photon, a process predicted in various promising dark matter models such as axion-like particles and sterile neutrinos. Recent and near-future photon detectors with a resolution $ R \equiv \lambda/\Delta\lambda = O(1000) $ are primarily optimized for the velocity dispersion of dark matter in the Milky Way. When performing indirect detection of dark matter in objects other than the Milky Way, one should take into account the contribution from Milky Way dark matter. As a result, the dark matter signal observed by a detector is predicted to exhibit a two-peak structure in many targets, owing to the Doppler shift, differences in radial velocities and the good energy resolution. An analysis incorporating this two-peak effect was performed using the latest XRISM observation data of the Centaurus galaxy cluster~\cite{XRISM:2025axf}. Although, due to the relatively short observation time, our derived limit is weaker than some existing limits, among dark matter searches in galaxy clusters our limit is one of the most stringent (at least in certain mass ranges). We also perform the usual single-peak analysis, for considering the various scenarios, that prefer narrow-line photon from the faraway galaxy cluster. Future data releases from XRISM as well as other observatories will further strengthen our conclusions.

In this paper, we derive the black hole solution in the context of nonlinear electrodynamics (NLED) coupled to a perfect fluid dark matter (PFDM) field. The resulting black hole solution interpolates between the $AdS$ Ayón--Beato--García (ABG) black hole in the absence of the PFDM field and the Schwarzschild black hole devoid of magnetic monopole charges and PFDM influence. A numerical investigation of the horizon structure and thermodynamic properties, including both local and global stability, is conducted for the obtained black hole solution. The thermodynamic quantities are shown to be modified by the presence of the NLED and PFDM fields. We observe that the behaviour of thermodynamical quantities of black holes depends on these parameters significantly. We also discuss the stability and phase transition dependency on these parameters.

We discuss a novel mechanism for generating dark matter from a fast-rolling scalar field, relevant for both inflation and rotating axion models, and apply it specifically to the (QCD) axion. Dark matter comes from scalar field fluctuations generated by the product of the curvature perturbation and the fast-rolling background field. These fluctuations can explain the totality of dark matter in a vast axion parameter space, particularly for the QCD axion, which will be targeted by upcoming experiments. We review the constraints on this mechanism and potential gravitational-wave signatures.

A rotation in the field space of a complex scalar field corresponds to a Bose-Einstein condensation of $U(1)$ charges. We point out that fluctuations in this rotating condensate exhibit sound-wave modes, which can be excited by cosmic perturbations and identified with axion fluctuations once the $U(1)$ charge condensate has been sufficiently diluted by cosmic expansion. We consider the possibility that these axion fluctuations constitute dark matter and develop a formalism to compute its abundance. We carefully account for the growth of fluctuations during the epoch where the complex scalar field rotates on the body of the potential and possible nonlinear evolution when the fluctuations become non-relativistic. We find that the resultant dark matter abundance can exceed the conventional and kinetic misalignment contributions if the radial direction of the complex scalar field is sufficiently heavy. The axion dark matter may also be warm enough to leave imprints on structure formation. We discuss the implications of this novel dark matter production mechanism -- {\it acoustic misalignment mechanism} -- for the axion rotation cosmology, including kination domination and baryogenesis from axion rotation, as well as for axion searches.

Galactic weak-scale Dark Matter (DM) particles annihilating into lepton-rich channels not only produce gamma-rays via prompt radiation but also generate abundant energetic electrons and positrons, which subsequently emit through bremsstrahlung or inverse Compton scattering (collectively called `secondary-radiation photons'). While the prompt gamma-rays concentrate at high-energy, the secondary emission falls in the MeV range, which a number of upcoming experiments (AMEGO, E-ASTROGAM, MAST...) will probe. We investigate the sensitivity of these future telescopes for weak-scale DM, focusing for definiteness on observations of the galactic center. We find that they have the potential of probing a wide region of the DM parameter space which is currently unconstrained. Namely, in rather optimistic configurations, future MeV telescopes could probe thermally-produced DM with a mass up to the TeV range, or GeV DM with an annihilation cross section 2 to 3 orders of magnitude smaller than the current bounds, precisely thanks to the significant leverage provided by their sensitivity to secondary emissions. We comment on astrophysical and methodological uncertainties, and compare with the reach of high-energy gamma ray experiments.

We propose an idea to build a bridge between reheating and late-time observations in quintessential inflation by backtracking the evolution of the inflaton field from the present time to the end of reheating. This idea is implemented when the potential gradient is negligible compared to the Hubble friction, rendering the inflaton field frozen, till the present time. We find a simple analytic relation between the reheating temperature and the observational parameters for dark energy, and numerically confirm its validity for typical models of quintessential inflation. This relation is universal and can apply to all quintessential inflation models with any reheating mechanism. It also implies that any quintessential inflation model with a successful reheating with the reheating temperature $1\textrm{MeV}\lesssim T_\textrm{re}\lesssim 10^{15}\textrm{GeV}$ predicts the equation of state of dark energy today extremely close to $-1$, i.e. $-1+10^{-60}\lesssim w_0\lesssim -1+10^{-24}$, unless the inflaton field unfreezes before the present time.

Like Johnson noise, where thermal fluctuations of charge carriers in a resistor lead to measurable current fluctuations, the internal variability of Earth's atmosphere leads to fluctuations in the infrared radiation emitted to space, creating "Earth's infrared background" (EIB). This background consists of fluctuations that are isotropic in space and red in time, with an upper bound of 400 km and 2.5 days on their spatiotemporal decorrelation, between meso-scale and synoptic-scale weather. Like the anisotropies in the Cosmic Microwave Background (CMB), which represent features of interest in the Universe, the anisotropies in Earth's infrared radiation represent features of interest in Earth's atmosphere. Unlike the CMB, which represents a historical record of the Universe since the Big Bang, the EIB represents Earth's climate in steady state.

Gravitational waves (GWs) signals detected by the LIGO/Virgo/KAGRA collaboration might be sourced (partly) by the merges of primordial black holes (PBHs). The conventional hierarchical Bayesian inference methods can allow us to study population properties of GW events to search for the hints for PBHs. However, hierarchical Bayesian analysis require an analytic population model, and becomes increasingly computationally expensive as the number of sources grows. In this paper, we present a novel population analysis method based on deep learning, which enables the direct and efficient estimation of PBH population hyperparameters, such as the PBH fraction in dark matter, $f_{\rm PBH}$. Our approach leverages neural posterior estimation combined with conditional normalizing flows and two embedding networks. Our results demonstrate that inference can be performed within seconds, highlighting the promise of deep learning as a powerful tool for population inference with an increasing number of GW signals for next-generation detectors.