Papers for Monday, Jun 02 2025

Accretion onto supermassive black holes (BHs) can launch relativistic jets that inject energy and momentum into their surroundings. Understanding how such feedback shapes large-scale accretion is key to bridging observations from galactic scales (e.g., the Bondi radius, $r_{\rm B}$) down to event horizon scales ($r_{\rm g}$), spanning 5-6 orders of magnitude. We tackle this challenge by varying the spatial scale separation across 2-4 orders of magnitude and performing some of the longest contiguous 3D general relativistic magnetohydrodynamic (GRMHD) simulations to date ($t \lesssim 4\times10^6 r_{\rm g}/c$), of Bondi-like accretion of rotating, non-relativistic gas with weak vertical magnetic fields onto a rapidly spinning BH, achieving inflow equilibrium out to $r \gtrsim 10^3 r_{\rm g}$. We find that, regardless of scale separation or ambient gas rotation, all simulations reach a magnetically arrested disk (MAD) state where the BH becomes magnetically saturated. In this state, the mass inflow rate follows a universal radial scaling: $\dot{M}_{\rm in}(r) \sim r^s$ with $s = 0.66 \pm 0.03$. The MAD state self-regulates through jets, outflows, and magnetic flux eruptions that can disrupt coherent angular momentum inflow, giving rise to a rocking accretion disk (RAD) state. This RAD state features chaotically oriented inflows, weak intermittent jets, and a steeper inflow slope of $s = 0.87 \pm 0.05$. The MAD and RAD BH accretion rates become comparable at typical scale separations, $r_{\rm B}/ r_{\rm g} \gtrsim 10^5$. Weaker RAD outflows allow large-scale inflows to resume, restoring the MAD state and enabling a recurring MAD-RAD cycle. These cycles can last tens of Bondi timescales, $t_{\rm B} \sim 0.2\,\text{Myr} \times (r_{\rm B}/10^{5} r_{\rm g})^{3/2} \times (M_{\rm BH}/10^9M_\odot)$, potentially setting the duty cycle of jetted AGN outbursts, such as in M87*.

This paper explores the impact of primordial black holes (PBHs) on the abundance of low-mass haloes and subhaloes in the dark and low-stellar-mass regime, and examines how these effects can be measured through fluctuations in strong lensing and brightness fluctuations in clusters of galaxies, providing potential ways to constrain the fraction of dark matter in PBHs. Various dark matter candidates leave unique imprints on the low-mass range of the halo mass function, which can be challenging to detect. Among these are hot and warm dark matter models, which predict a reduced abundance of low-mass structures compared to the $\Lambda$CDM model. Models with PBHs also affect this mass range, but in the opposite direction, producing an increase in low-mass objects. By examining lensing perturbations in galaxy clusters, constraints can be placed on the low-mass subhalo abundance and, therefore, on these different dark matter models. We aim to provide predictions useful for this type of perturbation in the PBH case. Additionally, we examine the abundance of haloes and subhaloes in the range where the stellar-to-halo mass relation rises steeply, which could be contrasted with brightness fluctuations in clusters caused by low-luminosity satellites. To do this, we run cosmological simulations using the {\small SWIFT} code, comparing a fiducial model with alternative inflationary models, both with and without PBHs. We find a significant excess of substructure in the presence of PBHs compared to $\Lambda$CDM, without altering the abundance of high-mass haloes at redshift zero. This increase reaches factors of $\sim6$ for extended PBH mass functions with exponential cutoffs at $M_{\rm PBH}=10^2M_\odot$ in the range of parameter space where they could make up all of the dark matter, and persists even for sub-percent PBH fractions with cutoffs at $M_{\rm PBH}=10^4M_\odot$.

In this work, as a follow-up to our similar analysis of Kepler's supernova remnant (SNR), we estimate total mass ratios of various ejecta elements in Tycho's SNR using Suzaku X-ray data. In our spectral analysis, we account for uncertainties arising from Suzaku's effective area calibration (5%-15%) and from the unknown filling factors of the various plasma components in our spectral model (1%-10%). We compare our calculated ejecta mass ratios to results from previous X-ray analyses of Tycho's SNR and to the nucleosynthesis results from Type Ia supernova simulations. Our estimated ejecta mass ratios for Tycho's SNR are only consistent with simulations that use a $\sim$90% attenuated $^{12}$C$+^{16}$O reaction rate (as for Kepler's SNR), are inconsistent with simulations involving a double detonation of a thick helium layer, and support a Type Ia explosion of normal luminosity where $\sim$85% of the ejecta has been heated by the reverse shock.

Supersonic turbulence plays a critical role in shaping astrophysical systems, from molecular clouds to the circumgalactic medium. Key properties of this turbulence include the Mach number, driving scale, and nature of the driving mechanism, which can be solenoidal (divergence-free), compressive (curl-free), or a mix of the two. A less studied property is the correlation time of the driving accelerations, $\tau_{\rm a}.$ While this timescale has a minimal impact on solenoidally-driven turbulence, we show that it has a strong impact on compressively-driven turbulence. Using high-resolution simulations with tracer particles, we analyze the evolution of density fluctuations, focusing on the PDF of the logarithmic density, $s$, and its rate of change, $\frac{ds}{dt},$ and the conditional statistics of $\frac{ds}{dt}$ and $\frac{d^2s}{dt^2}$. When the driving correlation time is comparable to the eddy turnover time, $\tau_{\rm a} \approx \tau_{\rm e},$ compressive driving leads to the formation of large, low-density voids in which the variance of $\frac{ds}{dt}$ is large. These are directly linked to sustained accelerated expansions, which results in a strong correlation between density and the divergence of the driving acceleration field. In contrast, when $\tau_{\rm a} \approx 0.1 \, \tau_{\rm e}$, compressive driving does not produce such voids, resulting in a narrower, less skewed distribution. We show using analytical estimates that $\tau_{\rm a}$ is may be significantly less than $\tau_{\rm e}$ in supernova-driven turbulence, highlighting the need to better understand the role of the driving correlation time in shaping the density structure of turbulent astrophysical systems.

We investigate the evolution of black holes on orbits with small inclinations ($i < 2^\circ$) to the gaseous discs of active galactic nuclei. We perform 3D adiabatic hydrodynamic simulations within a shearing frame, studying the damping of inclination by black hole-gas gravitation. We find that for objects with $i<3H_0R_0^{-1}$, where $H_0R_0^{-1}$ is the disc aspect ratio, the inclination lost per midplane crossing is proportional to the inclination preceding the crossing, resulting in a net exponential decay in inclination. For objects with $i>3H_0R_0^{-1}$, damping efficiency decreases for higher inclinations. We consider a variety of different AGN environments, finding that damping is stronger for systems with a higher ambient Hill mass: the initial gas mass within the BH sphere-of-influence. We provide a fitting formula for the inclination changes as a function of Hill mass. We find reasonable agreement between the damping driven by gas gravity in the simulations and the damping driven by accretion under a Hill-limited Bondi-Hoyle-Lyttleton prescription. We find that gas dynamical friction consistently overestimates the strength of damping, especially for lower inclination systems, by at least an order of magnitude. For regions in the AGN disc where coplanar binary black hole formation by gas dissipation is efficient, we find that the simulated damping timescales are especially short with $\tau_d < 10P_\mathrm{SMBH}$. We conclude that as the timescales for inclination damping are shorter than the expected interaction time between isolated black holes, the vast majority of binaries formed from gas capture should form from components with negligible inclination to the AGN disc.

The superfluid dark matter model offers an elegant solution to reconcile discrepancies between the predictions of the cold dark matter paradigm and observations on galactic scales. In this scenario, dark matter is composed of ultralight bosons with self-interactions that can undergo a superfluid phase transition in galactic environments. In this review, we explore the theoretical foundations of dark matter superfluidity, detailing the conditions required for the formation and stability of superfluid cores of astrophysical size. We examine the phenomenological consequences for galactic dynamics, including the impact on galaxy mergers, the formation of vortices, the behavior near supermassive black holes, modifications to dynamical friction, and the emergence of long-range interactions. By synthesizing theoretical developments with observational constraints, we aim to provide a comprehensive overview of the current status and future prospects of dark matter superfluidity as a viable extension of the standard cosmological model.

The streaming instability (SI), driven by aerodynamic coupling between solids and the gas under a global radial pressure gradient, concentrates solids and facilitates planetesimal formation. Unstratified simulations are commonly used to study the SI, based on the assumption that they approximate conditions near the disk midplane. However, it remains unclear how accurately these unstratified simulations capture the midplane dust-gas dynamics in stratified disks. To address this, we examine the saturated state of the SI in stratified simulations and compare dust-gas dynamics to those in unstratified simulations across various radial pressure gradients. To this end, we consider a dimensionless dust stopping time ($\tau_s$) of 0.1 and perform 2D axisymmetric, stratified simulations. We find that the formation of dust filaments during dust settling exhibits morphological similarities to those in unstratified simulations. In the saturated state, we find that as the pressure gradient increases, the velocity dispersions of the gas and dust, as well as the strength of dust diffusion, increase. Most importantly, at any given pressure gradient, the velocity dispersions and density distributions of the gas and dust in our stratified simulations closely match those in unstratified simulations. While further exploration across the parameter space is needed, our results suggest that, for $\tau_s=0.1$, unstratified simulations represents well the midplane dust--gas dynamics in stratified disks before any strong clumping occurs. Consequently, our results confirm that in the saturated state, the streaming turbulence in stratified simulations behaves similarly to that in unstratified simulations for the parameter values explored here.

The spatial distribution and linewidth of Mercury's sodium and potassium exosphere were observed using a combination of long-slit and high-resolution point spectroscopy. Effective temperatures were estimated from emission line profiles by forward modeling their Doppler broadening. These serve as an energy metric for collisionless gas that is inherently nonthermal. The Na gas at low and mid-latitudes ranges from 1200-1300 K along the noon meridian, in agreement with MESSENGER scale heights, increasing by ~200 K at the poles and terminator. This increase is attributed to the loss of low energy atoms to the surface during photon-driven transport antisunward. An escaping potassium tail was measured for the first time, observed to a distance of 10.4 RM with Na/K ~95 at 5.8 RM. Emission linewidths increase sharply between the dayside and escaping tail, with Na growing from about 1200 to 7500 K, and K from 750 to 8500 K by the time the gas reaches 4.3 RM downtail. Na D line profiles down the exotail also evolve from Gaussian to boxcar in shape. Both characteristics are interpreted as filtering of the nascent velocity distribution function, wherein low energy atoms on gravitationally bound trajectories are removed from the gas population, while high energy escaping atoms are retained. Na linewidths become invariant past 3.5 RM, placing this altitude as the ballistic apex of bound trajectories. In this way, Mercury's emissions prototype a novel technique towards a broader understanding of atmospheric escape, using emission line morphology to probe the transition between bound and escaping gas.

We present new observations of the black hole X-ray binary A0620-00 using the Mid-Infrared Instrument on the James Webb Space Telescope, during a state where the X-ray luminosity is 9 orders of magnitude below Eddington, and coordinated with radio, near-infrared and optical observations. The goal is to understand the nature of the excess mid-infrared (MIR) emission originally detected by Spitzer red-ward of 8 $\mu$m. The stellar-subtracted MIR spectrum is well-modeled by a power law with a spectral index of $\alpha=0.72\pm0.01$, where the flux density scales with frequency as $F_\nu \propto \nu^{\alpha}$. The spectral characteristics, along with rapid variability--a 40% flux flare at 15$\mu$m and 25% achromatic variability in the 5-12 $\mu$m range--rule out a circumbinary disk as the source of the MIR excess. The Low Resolution Spectrometer reveals a prominent emission feature at 7.5 $\mu$m, resulting from the blend of three hydrogen recombination lines. While the contribution from partially self-absorbed synchrotron radiation cannot be ruled out, we argue that thermal bremsstrahlung from a warm (a few $10^4$ K) wind accounts for the MIR excess; the same outflow is responsible for the emission lines. The inferred mass outflow rate indicates that the system's low luminosity is due to a substantial fraction of the mass supplied by the donor star being expelled through a wind rather than accreted onto the black hole.

The size distribution of planets with radii between 1 and $4 R_\oplus$ peaks near 1.4 and $2.2R_\oplus$, with a dip around $1.8 R_\oplus$ -- the so-called "radius valley." Recent statistical analyses suggest that planets within this valley ($1.5 < R < 2R_\oplus$) tend to have slightly higher orbital eccentricities than those outside it. The origin of this dynamical signature remains unclear. We revisit the "breaking the chains" formation model and propose that late dynamical instabilities -- occurring after disk dispersal -- may account for the elevated eccentricities observed in the radius valley. Our simulations show that sub-valley planets ($R < 2 R_\oplus$) are generally rocky, while those beyond the valley ($R > 2 R_\oplus$) are typically water-rich. Rocky planets that undergo strong dynamical instabilities and numerous late giant impacts have their orbits excited and their radii increased, ultimately placing them into the radius valley. In contrast, the larger, water-rich planets just beyond the valley experience weaker instabilities and fewer impacts, resulting in lower eccentricities. This contrast leads to a peak in the eccentricity distribution within the valley. The extent to which planets in the radius valley are dynamically excited depends sensitively on the orbital architecture before the orbital instability. Elevated eccentricities among radius valley planets arise primarily in scenarios that form a sufficiently large number of rocky planets within 100 days (typically $\gtrsim 5$) prior to instability, and that also host external perturbers ($P > 100$ days), which further amplify the strength of dynamical instabilities.

Bars are considered an efficient mechanism for transporting gas toward the central regions of galaxies, potentially enhancing nuclear activity. However, the extent to which bars influence active galactic nuclei (AGNs), and whether their efficiency varies with environment, remain open questions. In this study, we aim to quantify the role of bars in triggering AGNs by comparing the AGN fraction in barred and non-barred galaxies across different environments. We constructed a sample from the Galaxy Zoo DECaLS catalog, ensuring a control selection where both samples share similar distributions in stellar mass, redshift, magnitude, concentration index, and local density parameter. AGNs were identified using spectroscopic data from the Sloan Digital Sky Survey, yielding 1330 barred AGNs and 1651 unbarred AGNs. We use the [OIII]5007 luminosity (Lum[OIII]) and the accretion rate parameter R as indicators of nuclear activity. Based on these, we applied criteria to distinguish powerful from weak AGNs, allowing a more precise assessment of the bar's impact on the supermassive black hole. Our analysis reveals that barred galaxies tend to host a higher fraction of powerful AGNs. From Lum[OIII], we find that more active nuclei reside in massive, blue galaxies with young stellar populations. We also observe a slight tendency for barred galaxies to host less massive black holes accreting more efficiently. The classification of strong and weak bars shows that more prominent bars correlate with higher nuclear activity. While this trend shows no significant differences in intermediate-density environments, it becomes evident in both low- and high-density regions, where galaxies with strong bars show enhanced AGN activity.

Several models of nuclear dust in active galactic nuclei (AGN) have been presented in the literature to determine its physical and geometrical properties, usually assuming the dust density distribution as the main aspect producing differences in the mid-infrared (MIR) emission of AGNs. We present a study of the MIR emission of nearby AGNs by exploring the effects of dust distribution and chemical composition on the spectral energy distributions (SEDs) using radiative transfer simulations. Our model grid includes smooth, clumpy, and two-phase dust distributions, combined with two dust compositions: the interstellar medium (ISM) dust composition including large grains (up to $\rm{10 \ \mu m}$), and the oxide/silicate-based composition from Reyes-Amador et al. (2024). A synthetic SED library was generated and analysed both on a model-to-model basis and with observed MIR spectra from 68 AGNs. We found that dust density distribution and dust composition significantly influence the spectral shapes and silicate features at $10$ and $\rm{18 \ \mu m}$, especially at edge-on orientations. The smooth distribution produces stronger and broader silicate absorption features, while the clumpy distribution generates stronger features in emission. The two-phase distributions exhibit intermediate characteristics depending on the clumpiness fraction ($f_{\text{cl}}$) and filling factor ($f_{\text{fill}}$). The ISM dust composition with large grains is more suited to reproduce the observed features and a higher fraction of good fits, particularly with Type-2 SEDs, independently of dust density distributions. The Reyes-Amador et al. (2024) composition provides a larger number of good fits with Type-1 SEDs for $f_{\text{cl}} \leq 0.5$, and with Type-2 SEDs for $f_{\text{cl}} \geq 0.9$. This work shows that no single dust distribution or composition reproduces all observations.

Sunspots survive on the solar surface for time-scales ranging from days to months. This requires them to be in an equilibrium involving magnetic fields and hydrodynamic forces. Unfortunately, theoretical models of sunspot equilibrium are very simplified as they assume that spots are static and possess a self-similar and axially symmetric magnetic field. These assumptions neglect the role of small scale variations of the magnetic field along the azimuthal direction produced by umbral dots, light bridges, penumbral filaments, and so forth. We aim at studying whether sunspot equilibrium is maintained once azimuthal fluctuations in the magnetic field, produced by the sunspot fine structure, are taken into account. To this end we apply the FIRTEZ Stokes inversion code to spectropolarimetric observations to infer the magnetic and thermodynamic parameters in two sunspots located at disk center and observed with two different instruments: one observed from the ground with the 1.5-meter German GREGOR Telescope and another with the Japanese spacecraft Hinode. We compare our results with three dimensional radiative magnetohydrodynamic simulations of a sunspot carried out with the MuRAM code. We infer clear variations in the gas pressure and density of the plasma directly related to fluctuations in the Lorentz force and associated with the filamentary structure in the penumbra. Similar results are obtained in the umbra despite its lack of observed filamentary structure. Results from the two observed sunspots are in excellent qualitative and quantitative agreement with the numerical simulations. Our results indicate that the magnetic topology of sunspots along the azimuthal direction is very close to magnetohydrostatic equilibrium, thereby helping to explain why sunspots are such long-lived structures capable of surviving on the solar surface for days or even full solar rotations.

Context. The radio emission from magnetars is poorly understood and poorly characterized observationally, in particular for what concerns single pulses and sporadic events. The interest in it was boosted by the detection in 2020 of an extremely bright ms radio signal from the Galactic magnetar designated Soft Gamma Repeater (SGR) SGR J1935+2154, which occurred almost simultaneously with a typical magnetar short burst of X-rays. As of now, this event remains the Galactic radio pulse that is the most reminiscent of fast radio bursts (FRBs) and the only one with a sound association with a known progenitor. Aims. We aim to constrain the rate of impulsive radio events from magnetars, by means of an intensive monitoring using a high-sensitivity radio telescope. Methods. We performed a long-term campaign on seven Galactic magnetars (plus one candidate) using the Northern Cross transit radio telescope (in Medicina, Italy) searching for short timescales and dispersed radio pulses. Results. We obtained no detections in more than 560 hours of observation, setting an upper limit at 95% confidence level of <52 yr$^{-1}$ on the rate of events with energy >10$^{28}$ erg, which is consistent with limits in literature. Furthermore, under some assumptions on the magnetars properties and energetic behavior, we found that our upper limits point towards the fact that the entire population of FRBs observed cannot be explained by radio bursts emitted by magnetars.

Ly$\alpha$ spectroscopy with {\it JWST} is opening a new window on the sizes of ionized bubbles through the reionization epoch. Theoretical expectations suggest typical bubble radii should be 0.6--1.5 pMpc at $z\simeq 7$, assuming neutral hydrogen fractions of the intergalactic medium in the range $\overline{x}_{\rm HI}$=0.5--0.7. Here we investigate this picture using {\it JWST} to characterize the environment and Ly$\alpha$ emission of 292 galaxies at $7.0<z<8.5$ across 5 fields spanning a comoving volume of $1.3\times10^6$ Mpc$^3$. If the reionization predictions are correct, we should see overdensities and strong Ly$\alpha$ emission clustered in redshift windows of d$z=0.04-0.08$ and angular scales of 5--11 arcmin. We detect Ly$\alpha$ emission in 36 out of 292 galaxies, including nine new Ly$\alpha$ detections, two of which (in the UDS field) show extremely large equivalent widths (EW = $200_{-78}^{+50}$ A and $284_{-75}^{+56}$ A). We identify 13 significant (4--11$\times$) galaxy overdensities using redshifts from NIRCam grism and NIRSpec. Strong Ly$\alpha$ emitters are almost uniformly found in the overdensities, with nearly all located between the center and back of the structures. The overdensities that host the strong Ly$\alpha$ emitters span typical line-of-sight distances (d$z\sim 0.14$) and angular scales ($\sim 8$ arcmin) that are comparable to the predicted bubble sizes at $z\simeq 7$. We discuss evidence that the EGS is mostly ionized along a 24 pMpc sightline at $z\simeq 7.0-7.6$, based on the presence of 3 overdense structures and 10 Ly$\alpha$ emitters in this volume, and find such a large ionized region would pose tension with standard reionization models.

The recent report of a period in the active repeating Fast Radio Burster 20201124A and measurement of its spindown rate place bounds on the solid angle of its emission on the basis of energetics. The bound depends on the (unknown) efficiency of conversion of rotational energy to coherent radio emission and implies a lower bound on the Lorentz factor of the radiating charges. Bursts may be emitted along the magnetic dipole axis, in repeaters aligned with the rotational axis and the line of sight but misaligned in apparent non-repeaters. This may explain the difficulty of finding periodicity in repeaters and the low duty cycle of apparent non-repeaters.

Gas giant planets have been detected on eccentric orbits several hundreds of astronomical units in size around other stars. It has been proposed that even the Sun hosts a wide-orbit planet of 5-10 Earth masses, often called Planet Nine, which influences the dynamics of distant Trans-Neptunian objects. However, the formation mechanism of such planets remains uncertain. Here we use numerical simulations to show that very wide-orbit planets are a natural byproduct of dynamical instabilities that occur in planetary systems while their host stars are still embedded in natal stellar clusters. A planet is first brought to an eccentric orbit with an apoastron of several hundred au by repeated gravitational scattering by other planets, then perturbations from nearby stellar flybys stabilise the orbit by decoupling the planet from the interaction with the inner system. In our Solar System, the two main events likely conducive to planetary scattering were the growth of Uranus and Neptune, and the giant planets instability. We estimate a 5-10% likelihood of creating a very wide-orbit planet if either happened while the Sun was still in its birth cluster, rising to 40% if both were. In our simulated exoplanetary systems, the trapping efficiency is 1-5\%. Our results imply that planets on wide, eccentric orbits occur at least $10^{-3}$ per star.

In this work, the straight flux rope in the model of giant flares on magnetars (Meng et al. 2014) was replaced with a curved one and the equilibrium behavior of the flux rope was investigated. Two footpoints of the flux rope are anchored to the spherical surface of magnetar. The forces acting on the flux rope include magnetic tension, magnetic pressure, curvature force, gravity. The equilibrium in the flux rope, so as in the global configuration, is achieved as these forces offset each other. Changes in the background environment drive the configuration to evolve through a set of equilibria in a quasi-static fashion until the critical point is reached and the loss of equilibrium in the configuration occurs, invoking a giant flare. We establish a criterion to identify magnetars capable of producing giant flares. Among the four forces, the curvature force as well as the magnetic compression tend to expel the flue rope outward. In a given magnetic configuration, the curvature force and magnetic compression are proportional to the square of the current intensity of the flux rope, which is determined by the frozen-flux condition and background magnetic field strength. We find that only when $\eta = G M m / ({{{R^4}{B_0}^2}})< 0.48 $ is satisfied, the system reaches a critical point and potentially undergoes catastrophe. Here, $G, M, m, R$, and $B_{0}$ are the gravitational constant, the mass of neutron star, the mass of flux rope, the radius of neutron star, and the surface magnetic field strength of neutron star, respectively. The physical meaning of this criterion is that when $\eta \propto m / B_{0}^{2}$ is small enough, the curvature force and magnetic pressure can be sufficiently large to overcome gravitational confinement. This criterion establishes a basis for identifying magnetars capable of producing giant flares.

Together optical/near infrared integral field spectroscopy and resolved sub-millimetre interferometry data have mapped the ionised and molecular gas motions in nearly one thousand galaxies at redshifts $z>0.5$. While these measurements have revealed a number of key properties about the evolution of disc structure and kinematics, heterogenous techniques and samples have led to disparate findings - especially when comparing different dynamical tracers (e.g., H$\alpha$, [C$\scriptstyle\rm~II$], CO). In this paper we present a literature compilation of 237 disc galaxies with measurements of velocity dispersion and rotational velocity between $z=0.5-8$, a subset of 63 galaxies have measurements of molecular gas fractions. We explore the connection between disc velocity dispersion measurements over 8 Gyrs as traced by multiple phases with the expectations from Toomre stability models. When sample properties are taken into account (e.g., stellar mass, tracer) there is little evolution in disc dispersions between $z\sim1.5-8$, consistent with expectations from model assumptions. We find ionised gas dispersions are higher by $\sim2\times$ from molecular gas dispersions at a fixed gas mass. These results are sensitive to the molecular gas tracer with results from [C$\scriptstyle\rm~II$] showing mixed behaviour indicative of its multi-phase origin. The [C$\scriptstyle\rm~II$] kinematics can be reconciled with molecular and ionised gas tracers when star-formation rates are taken into account.

Assuming that white dwarf (WD) magnetic fields are generated by a crystallization- and rotation-driven dynamo, the impact of the late appearance of WD magnetic fields in cataclysmic variables (CVs) has been shown to potentially solve several long-standing problems of CV evolution. However, recent theoretical works show that the dynamo idea might not be viable and that the late appearance of WD magnetic fields might be an age effect rather than related to the cooling of the core of the WD. We investigated the impact of the late appearance of WD magnetic fields on CV evolution assuming that the fields appear at fixed WD ages. We performed CV population synthesis with the BSE code to determine the fractions of CVs that become magnetic atcdifferent evolutionary stages. These simulations were complemented with MESA tracks that take into account the transfer of spin angular momentum to the orbit which can cause a detached phase. We find that the observed fraction of magnetic CVs as a function of orbital period is well reproduced by our simulations, and that in many CVs the WD should become magnetic close to the period minimum. The detached phase generated by the transfer of spin angular momentum is longest for period bouncers. Interpreting the late appearance of strong WD magnetic fields as a simple age effect naturally explains the relative numbers of magnetic CVs in observed samples. As many period bouncers might detach for several gigayears, the late appearance of WD magnetic fields at a fixed age and independent of the core temperature of the WD can significantly reduce the predicted number of accreting period bouncers.

In this work we determine the total globular cluster (GC) counts and globular cluster system (GCS) total mass estimates for 27 extremely massive elliptical galaxies. The GC 2D spatial distributions of these galaxies were created from photometry of HST images using DOLPHOT in the near-IR wavelength range. The projected radial density profiles of these GCSs were determined using a Voronoi tessellation-based technique introduced in our previous paper. We then plot these galaxies on the GCS - halo mass relation alongside previously studied galaxies in the literature. The relation now extends across seven decades of halo mass. We find that the 1:1 slope of this relation holds out to the highest mass galaxies, although extremely massive BCG galaxies are shifted to higher GCS masses than their lower-mass galaxy counterparts. We find a negative correlation with massive galaxies' offset from the GCS - halo mass relation and the steepness of their GCS density profiles, and that this is being driven by the red GC populations. We suggest that the biggest influence in intrinsic scatter in the GCS - halo mass relation for massive galaxies is through a few major mergers resulting in accretion of massive satellites with old, red GC populations, rather than many accretions of small satellites with younger, blue GC populations.

Emission Line Galaxies (ELGs) are crucial for cosmological studies, particularly in understanding the large-scale structure of the Universe and the role of dark energy. ELGs form an essential component of the target catalogue for the Dark Energy Spectroscopic Instrument (DESI), a major astronomical survey. However, the accurate selection of ELGs for such surveys is challenging due to the inherent uncertainties in determining their redshifts with photometric data. In order to improve the accuracy of photometric redshift estimation for ELGs, we propose a novel approach CNN-MLP that combines Convolutional Neural Networks (CNNs) with Multilayer Perceptrons (MLPs). This approach integrates both images and photometric data derived from the DESI Legacy Imaging Surveys Data Release 10. By leveraging the complementary strengths of CNNs (for image data processing) and MLPs (for photometric feature integration), the CNN-MLP model achieves a $\sigma_{\mathrm{NMAD}}$ (normalised median absolute deviation) of 0.0140 and an outlier fraction of 2.57%. Compared to other models, CNN-MLP demonstrates a significant improvement in the accuracy of ELG photometric redshift estimation, which directly benefits the target selection process for DESI. In addition, we explore the photometric redshifts of different galaxy types (Starforming, Starburst, AGN, Broadline). Furthermore, this approach will contribute to more reliable photometric redshift estimation in ongoing and future large-scale sky surveys (e.g. LSST, CSST, Euclid), enhancing the overall efficiency of cosmological research and galaxy surveys.

In this article, we present the relationship between prominence eruptions (PEs) and coronal mass ejections (CMEs) from May 2010 to December 2019 covering most of solar cycle 24. We used data from the Atmospheric Imaging Assembly (AIA) for PEs and the Large Angle and Spectrometric Coronagraph (LASCO) for CMEs. We identified 1225 PEs, with 67% being radial, 32% transverse, and 1% failed PEs. The radial, transverse PEs, and the combined set have average speeds of ~53, 9, and 38 km/s, respectively. The PE association with CMEs is examined by assigning a confidence level (CL) from 0 (no association) to 3 (clear association). Out of 1225 PEs, 662 (54%) are found to be associated to CMEs including CL 1, 2, and 3. Our study reveals that the spatial and temporal relationships between PEs and CMEs vary over the solar cycle. During solar minima, CMEs tend to deflect towards the equator, possibly due to a stronger polar field. Temporal offsets are larger during solar maxima and smaller during the minima. This implies that the PEs appear in LASCO C2 FOV earlier during the minima than during the maxima. Among the 662 CMEs associated with PEs, 78% show clear bright core structures. Investigation of the morphological and temporal behavior of these CMEs indicate that the prominences evolves into CME cores at higher altitudes suggesting that PEs and CME cores are the same structure. The average speeds of the PEs, CME core, and CME leading edge are 62, 390, and 525 km/s, respectively. The speed of CME cores are more than the speed of PEs because the former are observed at larger heights where they have accelerated to higher speeds.

Power-law inflation has stood as a classical model in inflationary cosmology since the early 1980s, prized for its exact analytical solutions and ability to naturally resolve the Big Bang theory's horizon and flatness problems through exponential expansion. However, its simplest form appears incompatible with modern precision observations, motivating increasingly complex alternatives. In this work, we demonstrate previous predictions with Power-law inflation considered only a particular solution of the field equations, and derive the complete set of general analytical solutions that satisfy current theoretical and observational constraints. This finding revitalizes Power-law inflation as a viable framework, offering new possibilities for cosmological model-building while preserving its original mathematical elegance.

We present a decade-long investigation of a poorly studied cluster, Berkeley 65 (Be 65), using deep optical data from the telescopes of ARIES, Nainital Observatory. We estimate its radius ($R_{cluster}$ = 1.6$^{'}$, aspect ratio of $\sim$1.1), distance (2.0 $\pm$ 0.1 kpc) and age ($\sim$160 Myrs). A clear turn-off point at $\sim$1.7 M$_\odot$ in the mass function suggests the escape of low-mass stars, and the lower photometric mass compared to the dynamical mass indicates ongoing disruption due to external forces. Our long-baseline optical photometric data also identifies 64 periodic and 16 non-periodic stars in this region. We have presented the light curves and the classification of those variables. The periodic stars have periods ranging from $\sim$0.05 days to $\sim$3.00 days and amplitude ranges from $\sim$8 mmag to $\sim$700 mmag. The nonperiodic stars show variation from $\sim$30 mmag to $\sim$500 mmag. The periodic stars include main-sequence pulsating variables such as Slow Pulsating B-type, $\delta$ Scuti, RR Lyrae, and $\gamma$ Doradus. We report a detached binary system and rotating variables similar to BY Draconis-type stars exhibiting variable brightness caused by starspots, chromospheric activity, and magnetic field-related phenomena.

Photoionized gases are prevalent throughout the universe. In such gases, the ion concentration typically exhibits two response modes to radiation: a positive response in the low-ionization state and a negative response in the high-ionization state. Here, we report the discovery of a widespread misalignment at the boundary between the above two response modes, and identify a third mode-the hybrid response-through time-dependent photoionization simulations. This phenomenon arises from the asynchrony among the ionization rate, recombination rate, and ion column density. Among these, only the ionization rate can respond instantaneously to changes in radiation. Consequently, the initial rate of change in the column density of \( N_i \) ion is given by \( -N_i I_i + N_{i-1} I_{i-1} \). However, this quantity is typically nonzero at the peak of \( N_i \), leading to a misalignment between the boundaries of positive and negative responses. Such hybrid effects introduce additional complexity in the interpretation of gas properties, highlighting the need for further investigation.

We study the chromospheric LOS velocities during the GOES M3.2 flare (SOL2013-05-17T08:43) using simultaneous spectroscopic data of the He I 1083.0 nm triplet and Ca II 854.2 nm line. A filament was present in the flaring area. The observational data were acquired with the VTT (Tenerife, Spain) and covered the pre-flare, flare, and post-flare phases. Spectroscopic inversion techniques (HAZEL and STiC) were applied individually to He I and Ca II lines to recover the atmospheric parameters. Different inversion configurations were tested for Ca II and two families of solutions were found to explain the red asymmetry of the profiles: a redshifted emission feature or a blueshifted absorption feature. These solutions could explain two different flare scenarios (condensation vs. evaporation). The ambiguity was solved by comparing these results to the He I inferred velocities. At the front of the flare ribbon, we observed a thin, short-lived blueshifted layer. This is seen in both spectral regions but is much more pronounced in He I, with velocities of up to -10 km/s. In addition, at the front we found the coexistence of multiple He I profiles within one pixel. The central part of the ribbon is dominated by He I and Ca II redshifted emission profiles. A flare-loop system, visible only in He I absorption and not in Ca II, becomes visible in the post-flare phase and shows strong downflows at the footpoints of up to 39 km/s. In the flare, the Ca II line represents lower heights compared to the quiet Sun, with peak sensitivity shifting from $\log \tau \simeq -5.2$ to $\log \tau \simeq -3.5$. The inferred LOS velocities support a cool-upflow scenario at the leading edge of the flare. The solar filament in the region remained stable. The inclusion of the He I triplet in the analysis helped resolve the ambiguity between two possible solutions for the plasma velocities detected in the Ca II line.

This study presents the black hole accretion history (BHAH) of obscured active galactic nuclei (AGNs) identified from the JWST CEERS survey by Chien et al. (2024) using mid-infrared (MIR) SED fitting. We compute black hole accretion rates (BHARs) to estimate the black hole accretion density (BHAD), $\rho_{L_{\mathrm{disk}}}$, across $0 < z < 4.25$. MIR luminosity functions (LFs) are also constructed for these sources, modeled with modified Schechter and double power law forms, and corresponding BHAD, $\rho_{\mathrm{LF}}$, is derived by integrating the LFs and multiplying by the luminosity. Both $\rho_{\mathrm{LF}}$ extend to luminosities as low as $10^7 \, L_{\odot}$, two orders of magnitude fainter than pre-JWST studies. Our results show that BHAD peaks between redshifts 1 and 3, with the peak varying by method and model, $z \approx 1$--2 for $\rho_{L_{\mathrm{disk}}}$ and the double power law, and $z \approx 2$--3 for the modified Schechter function. A scenario where AGN activity peaks before cosmic star formation would challenge existing black hole formation theories, but our present study, based on early JWST observations, provides an initial exploration of this possibility. At $z \sim 3$, $\rho_{\mathrm{LF}}$ appears higher than X-ray estimates, suggesting that MIR observations are more effective in detecting obscured AGNs missed by X-ray observations. However, given the overlapping error bars, this difference remains within the uncertainties and requires confirmation with larger samples. These findings highlight the potential of JWST surveys to enhance the understanding of co-evolution between galaxies and AGNs.

Oscillatory magnetic reconnection is a periodic magnetic reconnection process, during which the current sheet's orientation and the magnetic connections change periodically. This periodic variation is generally considered to originate from the magnetic reconnection itself rather than from external driving processes. We conduct 2.5-dimensional radiative magnetohydrodynamic simulations to investigate the emergence of a magnetic flux tube from the convection zone into the lower corona, where the emerging magnetic fields reconnect with background ones. During the reconnection process within 5771 s, the current sheet's orientation has been reversed 41 times, corresponding to 40 oscillation periods. Notably, the longest period is 30 minutes, which is consistent with the previous observational results. We find that the main factor leading to the reversal of the current sheet's orientation is the quasi-periodic external force provided by the emergence of plasma and magnetic fields from the convection zone. We also find the shifting of the upward outflows from the reconnection region along the horizontal direction due to the alternating changes of the reconnection inflow and outflow regions. In addition to the quasi-periodic change of the current sheet orientation, the reconnection rate at the main X-point also oscillates with a period between 100-400 s, which corresponds to the period of p-mode oscillations.

Simulations using the Smoothed Particle Hydrodynamics (SPH) technique typically include numerical viscosity to model shocks and maintain particle order on the kernel scale. This numerical viscosity is composed of linear and quadratic terms, with coefficients $\alpha_{\rm SPH}$ and $\beta_{\rm SPH}$ respectively. Setting these coefficients too high results in excessive numerical dissipation, whereas setting them too low may lead to unwanted effects such as particle penetration, which also leads to excess dissipation. In this study, we simulate accretion discs using the SPH code {\sc phantom} to investigate the effective disc viscosity arising from numerical viscosity. We model steady-state coplanar and circular discs with different values of $\alpha_{\rm SPH}$ and $\beta_{\rm SPH}$, from which we determine the coefficients that lead to minimum levels of numerical viscosity by maximising the steady-state disc surface density for the same mass input rate. We find that, for planar and circular discs, the default values of the numerical viscosity parameters in the {\sc phantom} code can be too high particularly for the quadratic term. As higher values of the coefficients are required to adequately capture strong shocks in the flow, we suggest that the coefficient of the quadratic term should be time-dependent in a similar manner to the presently used ``switches'' on the linear term. This can be simply achieved by setting $\beta_{\rm SPH}$ to be a constant multiple of $\alpha_{\rm SPH}$ with $\alpha_{\rm SPH}$ determined by an appropriate switch, as previously advocated in the literature.

We investigate the strong gravitational lensing properties of fuzzy dark matter (FDM) halos, focusing on the magnification properties near radial critical curves (CCs). Using simulated lenses we compute magnification maps for a range of axion masses and halo configurations. We show that FDM produces enhanced central magnification and secondary CCs that are not easily reproduced by standard cold dark matter (CDM), even when including subhalos. The strength and scale of these effects depend primarily on the de~Broglie wavelength, governed by the axion and halo masses. We find that axion masses in the range $m_\psi \sim 10^{-22}$--$10^{-21}\,\mathrm{eV}$ in galaxy-mass halos lead to distinctive magnification distributions. Our results suggest that observations of highly magnified, compact sources near radial arcs, such as quasars or supernovae, could serve as a powerful test for the presence of FDM.

The intra-halo light (IHL) is the diffuse stellar component that surrounds galaxies, groups, and clusters. Its formation is intimately linked to the hierarchical assembly of the system, making it a key tracer of galaxy evolution. However, the low surface brightness (LSB) of the IHL makes it challenging to detect and also to distinguish from the point spread function (PSF) effect of the telescope. In this paper, we present two independent techniques that, when combined, provide a statistically robust estimation of the IHL component in galaxy groups and clusters. The first technique corrects for the PSF-scattering effect to obtain unbiased LSB measurements, while the second fits an exponential model to the IHL component using a Markov Chain Monte Carlo (MCMC) optimiser algorithm. To test our methodology, we build a set of 5440 Hyper Suprime-Cam Subaru Strategic Program Public Data Release 3 (HSC-SSP PDR3) mock observations of Galaxy And Mass Assembly (GAMA) groups, each containing an IHL component with a flux fraction ($\mathrm{f_{IHL}}$) ranging from 0.01 to 0.5. Our results demonstrate the importance of properly removing the PSF-scattered flux, especially at lower $\mathrm{f_{IHL}}$. Without the PSF correction, our IHL model overestimates the true flux by up to a factor of 100, and the effective radius by up to a factor of 10. Finally, we apply our methodology to real observations and estimate the $\mathrm{f_{IHL}}$ of the GAMA group G400138 using HSC-PDR3 UD data in the $\textit{g,r}$ and $\textit{i}$-bands, finding median IHL fractions of: $\mathrm{f_{g,IHL}}$ $\sim$ 0.19$^{+0.09}_{-0.01}$, $\mathrm{f_{r,IHL}}$ $\sim$ 0.08$^{+0.06}_{-0.02}$ and $\mathrm{f_{i,IHL}}$ $\sim$ 0.06$^{+0.04}_{-0.02}$.

The multi-messenger science using different observational windows to the Universe such as Gravitational Waves (GWs), Electromagnetic Waves (EMs), Cosmic Rays (CRs), and Neutrinos offer an opportunity to study from the scale of a neutron star to cosmological scales over a large cosmic time. At the smallest scales, we can explore the structure of the neutron star and the different energetics involved in the transition of a pre-merger neutron star to a post-merger neutron star. This will open up a window to study the properties of matter in extreme conditions and a guaranteed discovery space. On the other hand, at the largest cosmological scales, multi-messenger observations allow us to study the long-standing problems in physical cosmology related to the Hubble constant, dark matter, and dark energy by mapping the expansion history of the Universe using GW sources. Moreover, the multi-messenger studies of astrophysical systems such as white dwarfs, neutron stars, and black holes of different masses, all the way up to a high redshift Universe, will bring insightful understanding into the physical processes associated with them that are inaccessible otherwise. This white paper discusses the key cases in the domain of multi-messenger astronomy and the role of observatories in India which can explore uncharted territories and open discovery spaces in different branches of physics ranging from nuclear physics to astrophysics.

Matched filtering is a common method for detecting gravitational waves. However, the computational costs of searching large template banks limit the efficiency of classical algorithms when searching for massive black hole binary (MBHB) systems. In this work, a quantum matched filtering algorithm based on Grover's algorithm is applied to the MBHB signals. It is demonstrated that the quantum approach can reduce the computational complexity from $O(N)$ to $O(\sqrt{N})$ theoretically, where $N$ is the size of the template bank. Simulated results indicate that the quantum-enhanced approach significantly reduces computational costs. However, it is also found that the performance can degrade in some cases due to instability of the algorithm. This highlights the need for more robust and stable quantum search strategies.

We present a JWST NIRISS/SOSS transmission spectrum of the super-Earth GJ 357 b: the first atmospheric observation of this exoplanet. Despite missing the first $\sim$40 % of the transit due to using an out-of-date ephemeris, we still recover a transmission spectrum that does not display any clear signs of atmospheric features. We perform a search for Gaussian-shaped absorption features within the data but find that this analysis yields comparable fits to the observations as a flat line. We compare the transmission spectrum to a grid of atmosphere models and reject, to 3-$\sigma$ confidence, atmospheres with metallicities $\lesssim$100$\times$ solar ($\sim$4 g/mol) with clouds at pressures down to 0.01 bar. We analyse how the retention of a secondary atmosphere on GJ 357 b may be possible due to its higher escape velocity compared to an Earth-sized planet and the exceptional inactivity of its host star relative to other M2.5V stars. The star's XUV luminosity decays below the threshold for rapid atmospheric escape early enough that the volcanic revival of an atmosphere of several bars of CO$_2$ is plausible, though subject to considerable uncertainty. Finally, we model the feasibility of detecting an atmosphere on GJ 357 b with MIRI/LRS, MIRI photometry, and NIRSpec/G395H. We find that, with two eclipses, it would be possible to detect features indicative of an atmosphere or surface. Further to this, with 3-4 transits, it would be possible to detect a 1 bar nitrogen-rich atmosphere with 1000 ppm of CO$_2$.

Recent analyses joining data from the Cosmic Microwave Background (CMB), Baryon Acoustic Oscillations (BAO), and Type Ia Supernovae (SNIa) have provided strong evidence in favor of dynamical dark energy (DDE) over a simple cosmological constant. Motivated by these findings, we present new observational constraints on DDE based on the cross-correlation between DESI Luminous Red Galaxies (LRG) samples and CMB lensing ($\mathrm{CMB}_{\kappa} \times \mathrm{LRG}$), which effectively probes the impact of cosmological parameters on the growth of structure at the perturbative level. We demonstrate that, when combined with geometric measurements such as BAO and SNIa, this cross-correlation yields compelling statistical evidence for DDE exceeding $4\sigma$, including within simpler parametrizations such as the $w$CDM model. Remarkably, this evidence is independent of constraints from primary Planck CMB anisotropies data. These results highlight the robustness and potential of Galaxy-CMB lensing cross-correlation as a powerful observational probe of the dark sector, particularly when used in conjunction with geometric observables.

The classification of solar prominences has proven to be challenging due to their diverse morphologies and dynamical behaviour. Complexity is heightened when considering eruptive prominences, where the dynamics demand methods capable of capturing detailed structural information. While there exists a range of line-of-sight (LOS) and plane-of-sky (POS) techniques which have advanced our understanding of prominence motions, they are subject to limitations, emphasising the need for effective methods of extracting structural information from prominence dynamics. We present a proof-ofconcept for the spatial Rolling Hough Transform (RHT) algorithm, which identifies finescale structural orientation in the POS, applied to prominence structure and dynamics. We demonstrate the RHT approach using two contrasting prominence dynamics events using SDO/AIA 304 Å observations: (1) a quiet-Sun eruption, (2) activation (swirl) of a polar-crown prominence. By analysing the light curves and movies from each event, we divide the events into distinct dynamical phases: from slow rise to drainage. The spatial RHT method enables us to extract structural information and localised dynamics for both events and the different evolution phases. We develop a classification to label the prominences as either radially or tangentially oriented structures. The quiet-Sun eruption has a predominately tangential structure in the slow-rise phase, but displays greater radial features during/after the eruption. The polar-swirl activation initially shows a strong radial contribution, which diminishes as more tangential structures appear during/after the activation. Our results demonstrate the successful application of the spatial RHT to prominences, leading to the classification of individual prominences and an insight into their dynamics.

The inner Milky Way disk globular cluster NGC~6362 appears to exhibit tidal tails composed of stars that have proper motions and positions in the color-magnitude diagram similar to those of cluster stars. Because recent results seem also to show that these stars are distributed across the regions least affected by interstellar absorption and reproduce the observed composite star field density map, we carried out a detailed spectroscopic analysis of a number of chemical element abundances of tidal tail star candidates in order to investigate the relationship of them with NGC~6362. From European Southern Observatory's VLT@FLAMES spectra we found that the red giant branch stars selected as cluster's tidal tail stars do not have overall metallicities nor abundances of Mg, Ca, Sc, Ti, Cr, Ni and Ba similar to the cluster's ones. Moreover, they are mainly alike to stars that belong to the Milky Way thick disk, some of them could be part of the thin disk and a minor percentage could belong to the Milky Way halo star population. On the other hand, since the resulting radial velocities do not exhibit a distribution function similar to that of cluster's stars, we concluded that looking for kinematic properties similar to those of the cluster would not seem to be an approach for selecting cluster's tidal tail stars as suitable as previously thought.

Scientific CMOS (sCMOS) image sensors are a modern alternative to typical CCD detectors and are rapidly gaining popularity in observational astronomy due to their large sizes, low read-out noise, high frame rates, and cheap manufacturing. However, numerous challenges remain in using them due to fundamental differences between CCD and CMOS architectures, especially concerning the pixel-dependent and non-Gaussian nature of their read-out noise. One of the main components of the latter is the random telegraph noise (RTN) caused by the charge traps introduced by the defects close to the oxide-silicon interface in sCMOS image sensors, which manifests itself as discrete jumps in a pixel's output signal, degrading the overall image fidelity. In this work, we present a statistical method to detect and characterize RTN-affected pixels using a series of dark frames. Identifying RTN contaminated pixels enables post-processing strategies that mitigate their impact and the development of manufacturing quality metrics.

In this work, we perform a statistical inference of the classical background law governing the evolution of the temperature of the cosmic microwave background radiation (CMB), given by $T_{\rm CMB}(z) = T_0(1 + z)$. To this end, we employ Gaussian Process (GP) regression techniques to reconstruct the temperature evolution based on two observational datasets: (i) CMB-Sunyaev-Zel'dovich (SZ) cluster measurements and (ii) CMB-interstellar medium (ISM) interaction data. Our analysis reveals interesting results that may suggest potential deviations from the standard temperature-redshift relation, particularly at low redshifts ($z < 0.5$), where discrepancies up to $\sim$2$\sigma$ are observed. Additionally, we identify a mild but noteworthy tension, also at the $\sim$2$\sigma$ level, between our GP inferred value of the present-day CMB temperature, $T_{\rm CMB}(z=0)$, and the precise direct measurement from the COBE/FIRAS experiment. We also explore possible phenomenological implications of our findings, including interpretations associated with possible variations in fundamental constants, such as the fine-structure constant $\alpha$, which could provide a physical explanation for the observed deviations at low redshift.

The binarity of red supergiants (RSGs) influences their evolution and the fate of supernovae. We investigate the binary fraction of RSGs in the Andromeda Galaxy (M31) and Triangulum Galaxy (M33) using photometry from the Hubble Space Telescope (HST), which offers high spatial resolution to resolve more RSGs. A preliminary step involves identifying a reliable and complete RSG sample using the F110W $-$ F160W versus F160W diagram, yielding 2,612 RSGs from the Panchromatic Hubble Andromeda Treasury (PHAT) survey of M31 3,294 RSGs from the Panchromatic Hubble Andromeda Treasury: Triangulum Extended Region (PHATTER) survey of M33. These samples suggest total RSG populations in M31 and M33 of 6,563 and 7,572, respectively. These estimates significantly exceed previous ones from the ground-based observations, an increase attributed to the superior spatial resolution of the HST. The stellar parameters of these RSGs, including effective temperature ($T_{\mathrm{eff}}$), radius ($R$), and luminosity ($L$), are derived by fitting their spectral energy distribution (SED) across optical and near-infrared bands. Binary candidates are identified by detecting ultraviolet (UV) excesses in their SEDs compared to the single-star RSG model prediction. The binary fraction is determined to be 33.4% $\pm$ 0.9% for M31 and 30.9% $\pm$ 0.8% for M33. For more luminous RSGs with log $L/L_{\odot} > 4.0$, the binary fraction decreases to 31.6% $\pm$ 1.9% in M31 and increases to 34.7% $\pm$ 1.8% in M33, respectively. These results are in good agreement with predictions from the BPASS binary evolution model.

Benchmark brown dwarfs in wide binary systems are crucial for characterizing substellar objects and calibrating atmospheric and evolutionary models. However, brown dwarf benchmarks with subsolar metallicity, very cool temperatures, or suitability for dynamical mass measurements are rare, limiting our understanding across the full range of mass, age, and metallicity. We present the discovery of two new multiple systems containing T dwarf companions, identified through a targeted search using CatWISE and Gaia databases. L 122-88 AB is a wide binary comprising a mildly metal-poor M2 dwarf and a T5 dwarf, separated by 215.6 arcsec at a distance of 33.106+/-0.014 pc. Atmospheric model fitting to the near infrared spectrum of L 122-88 A suggests a mildly metal-poor composition ([Fe/H] = -0.2). UPM J1040-3551 AB is a candidate hierarchical triple system at 25.283+/-0.013 pc, consisting of an M4 dwarf and a probable unresolved spectral binary of T7 and T8 dwarfs, separated by 65.48 arcsec from the primary. The H-alpha emission detected in UPM J1040-3551 A indicates an age range of 0.3-2.0 Gyr. This age estimate suggests that the T8 component has a mass between 9 and 28 Jupiter masses, potentially classifying it as a planetary-mass object. These systems augment the sample of benchmark brown dwarfs, particularly in the underexplored regime of cool temperature, providing valuable opportunities for refining our understanding of substellar objects.

High-spatial-resolution observations of disks around young stars suggest planetary systems begin forming early, during the protostellar phase (< 1 Myr) when stars accrete most of their mass via infall from the surrounding cloud. During this era shocks are expected to be ubiquitous around the gaseous accretion disk due to supersonic infall that strikes the disk. We investigate the role of shocks using a theoretical and modeling framework we call the shock twist-angle Keplerian (STAK) disk, connecting the disk and infalling envelope gas via a shock using general physical principles. Briefly, at the shock, energy is dissipated while angular momentum is conserved, so that the infalling gas must change direction sharply, yielding a bend or twist in the streamlines. The model's pre-shock gas follows free-fall parabolic trajectories, while the post-shock gas is on lower-energy, elliptical orbits. We construct synthetic observations and find that the deviations from circular Keplerian orbits are detectable in Doppler-shifted molecular spectral lines using radio interferometers such as ALMA. Specifically, the STAK model leads to line emission intensity and velocity-moment maps that are asymmetric and offset with respect to the disk structure traced by the dust continuum. We examine archival ALMA data for the class 0/I protostar L1527 and find the C$^{18}$O velocity moment map has features resembling the disk plus envelope emission that naturally arise when the two are connected by a shock. Thus, spectral line observations having sub-km/s spectral resolution and angular resolution sufficient to fully resolve the disk can reveal protostars' envelope-disk shocks.

$\delta N$ formalism is a useful method to calculate the curvature perturbation. Contrary to what it is typically done in the literature, we re-formulate the $\delta N$ formalism by using the $e$-folding number $n$ counted forward in time. For a fixed initial time $\bar{n}_0$, the probability density function (PDF) of the initial conditions $\delta\phi_0$ and $\delta\pi_0$ are specified by the solutions of the perturbation equation on subhorizon scales. As $\delta\pi_0$ is fully correlated with $\delta\phi_0$ after horizon exit, we find a simple formula to calculate the curvature perturbation as well as its PDF by using the $\delta N$ method reformulated in terms of $n$, the $\delta n$ formalism.

We present the a near complete spectral energy distribution (SED) for an extrasolar world: the T8 brown dwarf 2MASS~J04151954$-$0935066. Spanning from optical to mid-infrared (0.7--20.4 micron) wavelengths, the SED for this substellar atmosphere is constructed from new JWST NIRSpec G395H ($R\sim$2700) and Magellan FIRE echelle ($R\sim$8000) near-infrared spectra, along with MIRI mid-infrared photometry complemented by spectra from Keck I, IRTF, Magellan, AKARI, Spitzer and photometry from various surveys and missions. The NIRSpec G395H spectrum reveals strong molecular absorptions from NH$_{3}$, CH$_{4}$, H$_{2}$S, CO$_{2}$ and H$_{2}$O at approximately 3.00, 3.35, 3.95, 4.25, and 5.00 micron respectively, along with the presence of a CO absorption feature detected mainly at $\sim$ 4.6 micron. We detect no absorption of near-infrared K I doublets in the $R\sim8000$ FIRE spectra. In the mid-infrared IRS spectrum, we tentatively identify a new CO$_{2}$ feature at 14--16 micron. The comprehensive SED allows us to empirically constrain bolometric luminosity, effective temperature, mass and radius. Additionally, we demonstrate that the NIRSpec G395H resolution, the highest allowable by JWST, enables a precise radial velocity measurement of $47.1\pm1.8$ km s$^{-1}$ for the object, in agreement with previous measurements.

The discovery of ultra-high-energy neutrinos by IceCube marked the beginning of neutrino astronomy. Yet, the origin and production mechanisms of these neutrinos remain open questions. With the recent observation of the highest-energy neutrino event to date by the KM3NeT collaboration, transient sources - astrophysical objects that emit particles in brief, localized bursts - have emerged as promising candidates. In this work, we revisit the identification of such sources in IceCube and future neutrino telescopes, focusing on how both the timing and sky localization of the source affect the detection sensitivity. We highlight the crucial role of the source's right ascension in determining the effective area of detectors not located at the poles, such as KM3NeT, and present a framework to consistently account for this dependence. As a case study, we investigate evaporating primordial black holes (PBHs) as transient neutrino sources, showing that the detection prospects and localization accuracy are strongly influenced by the PBH's position in the sky. Our results emphasize the complementarity between neutrino and gamma-ray observatories and showcase the potential of a global network of neutrino detectors to identify and localize transient events that might be missed by traditional photon-based instruments.

A number of asymptotic giant branch (AGB) stars are known to exhibit UV excess and/or X-ray emission. These have been considered signposts of a hot white dwarf (WD) companion in a symbiotic system (SySt), but AGB stars are so bright that they easily outshine these companions hampering their detection at optical wavelengths. A recent multi-wavelength investigation on the X-ray-emitting AGB (X-AGB) star Y Gem has confirmed the presence of a WD companion and, thus, its SySt nature. Our goal is to explore the true nature of another X-AGB star, namely CGCS 6306, to investigate whether some objects from this group may in fact be unnoticed symbiotic systems with AGB donors. Optical spectra and photometric data, together with X-ray observations, have been analyzed to investigate the properties of the stellar components and accretion process in CGCS 6306. CGCS 6306 is a carbon Mira with a pulsation period of 362 days. Its optical spectrum exhibits the typical saw-shaped features of molecular absorptions in addition to H I and He I recombination and [O I] and [O III] forbidden emission lines. The H$\alpha$ line profile is broad, which can be interpreted as evidence for an accretion disk. The X-ray spectrum is hard, typical of highly-extincted hot plasma emission, and the X-ray luminosity is $\approx10^{32}$ erg s$^{-1}$. The detection of high-excitation optical emission lines and the X-ray properties of CGCS 6306 confirm the presence of a WD companion, making it a bona-fide $\delta$-type X-SySt. Its X-ray luminosity is comparable to that of Y Gem, the other X-AGB confirmed to be a SySt, which was found to exhibit a high accretion rate. The lack of suitable information on the UV and blue optical properties of CGCS 6306, however, precludes a definitive estimate of the accretion rate in this system. Since CGCS 6306 is a carbon Mira, it adds to the small group of Galactic carbon SySts.

Giant Molecular Filaments are opportune locations in our Galaxy to study the star-forming interstellar matter and its accumulation on spatial scales comparable to those now becoming available for external galaxies. We mapped the emission of HCN(1$-$0), HCO$^+$(1$-$0), and N$_2$H$^+$(1$-$0) towards two of these filaments, one associated with the Sagittarius arm and one with an interarm area. Using the data alongside the COHRS $^{12}$CO(3$-$2), the CHIMPS $^{13}$CO(3$-$2), and $\textit{Herschel}$-based column density maps, we evaluate the dense gas tracer emission characteristics and find that although its filling factor is the smallest among the studied species, N$_2$H$^+$ is the best at tracing the truly dense gas. Significant differences can be seen between the $^{13}$CO, HCN, and $N$(H$_2$)$_{\mathrm{dust}}$ levels of the arm and interarm, while the N$_2$H$^+$ emission is more uniform regardless of location, meaning that the observed variations in line ratios like N$_2$H$^+$/HCN or N$_2$H$^+$/$^{13}$CO are driven by species tracing moderate-density gas and not the star-forming gas. In many cases, greater variation in molecular emission and ratios exist between regions inside a filament than between the arm and interarm environments. The choice of measure of the dense gas and the available spatial resolution have deep impact on the multi-scale view of different environments inside a galaxy regarding molecular emissions, ratios, and thus the estimated star formation activity.

Observations from DESI DR2 are challenging the $\Lambda$CDM paradigm by suggesting that the equation-of-state parameter of dark energy evolves across $w = -1$, a phenomenon known as the Quintom scenario. Inspired by this development, we present a staged review of Quintom cosmology including its theoretical foundations, observational supports, and implications as well as possible extensions. We first trace the historical progression from Einstein's static cosmological constant to modern dynamical dark energy, summarizing recent cosmological constraints that favor an evolving $w(z)$ along time. A key focus is the theoretical no-go theorem for dark energy showing that no single canonical field or perfect fluid model can smoothly cross the $w = -1$ boundary. We then survey viable Quintom constructions, including two-field models, single-scalar fields with higher derivatives, modified gravity frameworks, and an effective field theory approach that unifies these mechanisms. Possible interactions of Quintom fields with ordinary matter and the potential roles in yielding non-singular universe solutions are discussed.

Few phenomenological models tend to favour higher values of the Hubble parameter, often at the expense of invoking phantom transitions. These models achieve this without introducing additional parameters, akin to the simplicity of the concordance $\Lambda$CDM model. In this work, we investigate two such models -- Phenomenologically Emergent Dark Energy (PEDE) and Granda-Oliveros Holographic Dark Energy (GOHDE) -- to assess how correlations between $H_0$ and $\Omega_m$, as well as the choice of datasets, influence conclusions regarding their potential to address the Hubble tension at the background level. We find that minimally extended versions of these models favour notably low values for the Hubble parameter, with the perceived preference for higher values driven by the associated prior. Excluding BAO Ly$\alpha$-$H(z)$ data points at a redshift of $\sim 2.3$ results in a Hubble parameter that remains in significant tension with SH0ES measurements. In contrast, including these data points favours a higher $H_0$, as they suggest a relatively lower matter density within the framework of the assumed fiducial cosmology. Additionally, recent DESI DR1 and DR2 data exhibit mild tension with BAO-$H(z)$ estimates from SDSS. We demonstrate that the inclusion of stringent constraints, such as the CMB shift-parameter along with Pantheon$^+$, on the effective pressure less matter density significantly impacts the estimation of the Hubble parameter. Finally, reinterpreting these models in terms of interacting dark sectors with $Q = 3H\gamma_{\Lambda}\tilde{\rho}_{m}$ reveals that addressing the Hubble tension necessitates a varying $\gamma_{\Lambda}$ characterised by a singular sign-switch behaviour. This phantom behaviour, or equivalently, the onset of violation of the null energy condition in the future, is crucial for minimal models to solve the Hubble tension.

We re-examine the 7,070 candidate ultra-diffuse galaxies (UDGs) in the SMUDGes survey and provide classifications based on their visual morphology. Among the more interesting cases, we identify objects along a low surface brightness galaxy merger sequence (ongoing mergers (8) and post-mergers (7)) and a distinct set of dwarf ring galaxies (29). The ring galaxies are hypothesized to be the result of nearly polar-axis collisions, but the responsible companions are undetected. We also highlight objects in the catalog that appear to be tidally affected (68), thereby cautioning that their cataloged parameters may be unreliable. Finally, we identify contaminants of various types in the catalog, leaving 6,553 as viable undisturbed UDG candidates. We discuss all categories and provide example images of the more interesting ones.

It has long been known that a large population of Be/X-ray Binaries (BeXRBs) exists in the Milky Way's neighboring dwarf galaxy, the Small Magellanic Cloud (SMC), due to a recent period of intense star formation. Since 2016, efforts have been made to monitor this population and identify new BeXRBs through the Swift SMC Survey (S-CUBED). S-CUBED's weekly observation cadence has identified many new BeXRBs that exist within the SMC, but evidence suggests that more systems exist that have thusfar escaped detection. A major challenge in identifying new BeXRBs is their transient nature at high-energy wavelengths, which prevents them from being detected via their X-ray emission characteristics when not in outburst. In order to identify sources that may have been missed due to a long period of quiescence, it becomes necessary to devise methods of detection that rely on wavelengths at which BeXRBs are more persistent emitters. In this work, we attempt to use archival analysis of infrared, optical, and ultraviolet observations to identify new candidate BeXRBs that have been overlooked within the S-CUBED source catalog. Using X-ray/optical selection of source properties, unsupervised clustering, SED-fitting to VizieR archival measurements, and ultraviolet light curve analysis, we are able to identify six new candidate BeXRB systems that otherwise would have been missed by automated analysis pipelines. Using these results, we demonstrate the use of ultraviolet through near-infrared observational data in identifying candidate BeXRBs when they cannot be identified using their X-ray emission.

Measuring the astrometric and spectroscopic data of stars orbiting the central black hole in our galaxy (Sgr A*) offers a promising way to measure relativistic effects. In principle, the "no-hair" theorem can be tested at the Galactic Center by monitoring the orbital precession of S-stars due to the angular momentum (spin) and quadrupole moment of Sgr A*. Closer-in stars, more strongly affected by the black hole's rotation, may be required. GRAVITY+ could detect such stars that are currently too faint for GRAVITY. We aim to analytically and numerically characterize orbital reorientations induced by spin-related effects of Sgr A* up to the second post-Newtonian (2PN) order. We use the two-timescale method to derive the 2PN analytical expressions of the secular evolution of the orbital parameters that are related to the observer. To study the interaction between the orbital and spin orientations, we introduce observer-independent quantities that offer insight into the Kerr geometry. We also use the post-Newtonian code OOGRE to simulate hypothetical stars orbiting closer to Sgr A*, where spin and quadrupole effects are stronger. This enables comparison with our analytical predictions. We exhibit three orbital-timescale precession rates that encode the in-plane pericenter shift and the out-of-plane redirection of the osculating ellipse. We provide the 2PN expressions of these precession rates and express the orbit-integrated associated angular shifts of the pericenter and of the ellipse axes. We relate these orbital-timescale precession rates to the secular-timescale precession of the orbital angular momentum around the black hole spin axis. We consider that the theoretical insight we provide in this article will be useful in constraining the spin effect of Sgr A* with GRAVITY+ observations.

Accurate parameter estimation from cosmic microwave background data requires reliable likelihood modeling, particularly at large angular scales where angular power spectrum estimators exhibit non-Gaussian statistics. We present a novel approach, based on the Hamimeche-Lewis formalism, that marginalizes over auto-spectra, thus reducing residual biases from noise misestimation and partial sky coverage. We validate our approach by simulating three independent CMB channels, or data splits, in a multi-field setting, comparing to the pixel-based likelihood ground truth estimates for the optical depth $\tau$ and the tensor-to-scalar ratio $r$. We benchmark our method against the main power spectrum based alternatives available in the literature, showing that it outperforms all of them in terms of accuracy, while remaining fast and computationally efficient.

A novel methodology to obtain global transonic solutions around compact objects is reported here. A unified methodology to obtain accretion as well as wind solutions around these objects has been presented. Flows around compact objects are dissipative, and the conservation equations are therefore stiff. In such conditions, obtaining of sonic point(s) and hence, the transonic solution is not trivial. The conserved equations of motion fail to integrate in the presence of realistic viscosity, thereby making it difficult to obtain a global solution. This inhibits one from getting an actual picture of an astrophysical flow. The current work addresses this long-standing issue of obtaining solutions for both accretion and wind. The methodology developed utilises the inner boundary conditions and takes recourse to implicit-explicit (ImEx) integration schemes, to obtain general global transonic accretion and wind solutions. This is the first time such an attempt has been made. Current work considers the different cooling processes like bremsstrahlung, synchrotron and their inverse-Comptonizations, which are found to affect the thermodynamics of the flow. This methodology could successfully generate all topologies of global solutions, multiple sonic point regime, as well as shocks. A broad parameter space study has been done in this work. In an upcoming part II of the paper, a detailed discussion on the spectra and luminosity of the accretion and wind solutions has been presented.

STARBURST99 is a population synthesis code tailored to predict the integrated properties or observational characteristics of star-forming galaxies. Here we present an update to STARBURST99 where we port the code to python, include new evolutionary tracks both rotating and non-rotating at a range of low metallicity environments. We complement these tracks with a corresponding grid of new synthetic SEDs. Additionally we include both evolutionary and spectral models of stars up to 300-500Msol. Synthesis models made with the python version of the code and new input stellar models are labelled pySTARBURST99. We make new predictions for many properties, such as ionising flux, SED, bolometric luminosity, wind power, hydrogen line equivalent widths and the UV beta-slope. These properties are all assessed over wider coverage in metallicity, mass and resolution than in previous versions of STARBURST99. A notable finding from these updates is an increase in H I ionising flux of 0.3 dex in the first 2Myr when increasing the upper mass limit from 120 to 300Msol. Changing metallicity has little impact on H I in the first 2Myr (range of 0.015 dex from Z = 0.02 to 0.0) but lower metallicities have higher H I by 1 dex (comparing Z = 0.02 to 0.0004) at later times, with Z = 0.0 having even higher H I at later times. Rotating models have significantly higher H I than their equivalent non-rotating models at any time after 2Myr. Similar trends are found for He I and He II, bolometric luminosity and wind momentum, with more complex relations found for hydrogen line equivalent widths and UV beta-slopes.

We describe the SPHEREx Sky Simulator, a software tool designed to model science data for NASA's SPHEREx mission that will carry out a series of all-sky spectrophotometric surveys at $\sim$6'' spatial resolution in 102 spectral channels spanning 0.75 to 5 $\mu$m. The Simulator software implements models for astrophysical emission, instrument characteristics, and survey strategy to generate realistic infrared sky scenes as they will be observed by SPHEREx. The simulated data includes a variety of realistic noise and systematic effects that are estimated using up-to-date astrophysical measurements and information from pre-launch instrument characterization campaigns. Through the pre-flight mission phases the Simulator has been critical in predicting the impact of various effects on SPHEREx science performance, and has played an important role guiding the development of the SPHEREx data analysis pipeline. In this paper, we describe the \skysim\ architecture, pre-flight instrument and sky models, and summarize high-level predictions from the Simulator, including a pre-launch prediction for the 5$\sigma$ point source sensitivity of SPHEREx, which we estimate to be $m_{\rm AB}$ 18.5--19 from 0.75 to 3.8~$\mu$m and $m_{\rm AB}$ 16.6--18 from 3.8 to 5 $\mu$m, with the sensitivity limited by the zodiacal light background at all wavelengths. In the future, on-orbit data will be used to improve the Simulator, which will form the basis of a variety of forward-modeling tools that will be used to model myriad instrumental and astrophysical processes to characterize their systematic effects on our final data products and analyses.

The recent KM3NeT observation of the ${\cal O}(100~{\rm PeV})$ event KM3-230213A is puzzling because IceCube with much larger effective area times exposure has not found any such events. We propose a novel solution to this conundrum in terms of dark matter (DM) scattering in the Earth's crust. We show that intermediate dark-sector particles that decay into muons are copiously produced when high-energy ($\sim100~\text{PeV}$) DM propagates through a sufficient amount of Earth overburden. The same interactions responsible for DM scattering in Earth also source the boosted DM flux from a high-luminosity blazar. We address the non-observation of similar events at IceCube via two examples of weakly coupled long-lived dark sector scenarios that satisfy all the lab-based constraints. We calculate the corresponding dark sector cross sections, lifetimes and blazar luminosities required to yield one event at KM3NeT, and also predict the number of IceCube events for these parameters that can be tested very soon. Our proposed DM explanation of the event can also be distinguished from a neutrino-induced event in future high-energy neutrino flavor analyses, large-scale DM direct detection experiments, as well as at future colliders.

We investigate the fully relativistic spherical collapse model of a uniform distribution of mass $M$ with initial comoving radius $\chi_*$ and spatial curvature $k \equiv 1/\chi_k^2 \le 1/\chi_*^2$ representing an over-density or bounded perturbation within a larger background. Our model incorporates a perfect fluid with an evolving equation of state, $P = P(\rho)$, which asymptotically transitions from pressureless dust ($P = 0$) to a ground state characterized by a uniform, time-independent energy density $\rho_{\rm G}$. This transition is motivated by the quantum exclusion principle, which prevents singular collapse, as observed in supernova core-collapse explosions. We analytically demonstrate that this transition induces a gravitational bounce at a radius $R_{\rm B} = (8 \pi G \rho_{\rm G}/3)^{-1/2}$. The bounce leads to an exponential expansion phase, where $P(\rho)$ behaves effectively as an inflation potential. This model provides novel insights into black hole interiors and, when extended to a cosmological setting, predicts a small but non-zero closed spatial curvature: $ -0.07 \pm 0.02 \le \Omega_k < 0$. This lower bound follows from the requirement of $\chi_k \ge \chi_* \simeq 15.9$ Gpc to address the cosmic microwave background low quadrupole anomaly. The bounce remains confined within the initial gravitational radius $r_{\rm S} = 2GM$, which effectively acts as a cosmological constant $\Lambda$ inside $r_{\rm S}=\sqrt{3/\Lambda}$ while still appearing as a Schwarzschild black hole from an external perspective. This framework unifies the origin of inflation and dark energy, with its key observational signature being the presence of small but nonzero spatial curvature, a testable prediction for upcoming cosmological surveys.

The "ringdown" radiation emitted by oscillating black holes has great scientific potential. By carefully predicting the frequencies and amplitudes of black hole quasinormal modes and comparing them with gravitational-wave data from compact binary mergers we can advance our understanding of the two-body problem in general relativity, verify the predictions of the theory in the regime of strong and dynamical gravitational fields, and search for physics beyond the Standard Model or new gravitational degrees of freedom. We summarize the state of the art in our understanding of black hole quasinormal modes in general relativity and modified gravity, their excitation, and the modeling of ringdown waveforms. We also review the status of LIGO-Virgo-KAGRA ringdown observations, data analysis techniques, and the bright prospects of the field in the era of LISA and next-generation ground-based gravitational-wave detectors.

Searches for gravitational waves from compact binary coalescences employ a process called matched filtering, in which gravitational wave strain data is cross-correlated against a bank of waveform templates. Data from every observing run of the LIGO, Virgo, and KAGRA collaboration is typically analyzed in this way twice, first in a low-latency mode in which gravitational wave candidates are identified in near-real time, and later in a high-latency mode. Such high-latency analyses have traditionally been considered more sensitive, since background data from the full observing run is available for assigning significance to all candidates, as well as more robust, since they do not need to worry about keeping up with live data. In this work, we present a novel technique to use the matched filtering data products from a low-latency analysis and re-process them by assigning significances in a high-latency way, effectively removing the need to perform matched filtering a second time. To demonstrate the efficacy of our method, we analyze 38 days of LIGO and Virgo data from the third observing run (O3) using the GstLAL pipeline, and show that our method is as sensitive and reliable as a traditional high-latency analysis. Since matched filtering represents the vast majority of computing time for a traditional analysis, our method greatly reduces the time and computational burden required to produce the same results as a traditional high-latency analysis. Consequently, it has already been adopted by GstLAL for the fourth observing run (O4) of the LIGO, Virgo, and KAGRA collaboration.

The search for dark matter is one of the crucial open problems in both particle physics and cosmology. If dark matter scatters with Standard Model particles, it could accumulate inside the Earth and begin to annihilate, producing heat within the Earth's core. While past work has been done on the effect that this heat would have once it reached the surface, we model the flow of heat through the Earth's core by numerically solving the heat equation to model dark matter's effect on the interior of the planet. We compute how long it takes for the core to come into thermal equilibrium and show that for a wide range of dark matter parameters, a substantial fraction of the inner core would be melted by dark matter annihilation. Our analysis produces new limits on dark matter annihilating in the Earth, points out important new effects that must be considered when studying planetary heating by dark matter, and suggests new dark matter observables that could be searched for in exoplanet populations.

This paper explores radial and non-radial oscillations of protoneutron stars (PNSs) as they evolve from hot, neutrino-rich configurations through deleptonization to cold, catalyzed states. The equation of state (EoS) is modeled using a density-dependent relativistic mean-field framework, with stellar evolution characterized by changes in entropy and lepton fraction. Both nucleonic and hyperonic compositions are considered. Non-radial $f$- and $p_1$-mode oscillations are computed using both the Cowling approximation and full general relativity. Trapped neutrinos initially increase the error of the Cowling approximation for $f$-modes, which decreases during deleptonization and rises again in the cold phase. In contrast, $p_1$-mode errors peak during intermediate stages due to evolving pressure and density gradients. The emergence of hyperons modestly raises oscillation frequencies in both modes. Existing universal relations for $f$-mode frequency and damping time lack model independence for PNSs, motivating a more robust relation. In particular, our proposed universal relation involving the moment of inertia and $\tilde{\eta}$ shows strong agreement across all evolutionary phases, offering a temperature-sensitive, model-independent scaling for asteroseismology. Radial oscillations of a $1.4,M_\odot$ PNS are also studied for different EoSs. Our results show that displacement ($\xi$) and pressure perturbation ($\eta$) profiles are highly sensitive to thermal state, composition, and compactness. Hyperonic stars show higher frequencies, altered node structures, and stronger pressure perturbations due to EoS softening. Differences in frequency separation $\Delta \nu_n$ and fundamental frequency $\nu_0$ between nucleonic and hyperonic models provide clear observational diagnostics for probing PNS interiors and constraining the dense matter EoS.

We report on the first observation of electroluminescence and charge amplification with a Virtual Cathode Chamber (VCC) microstrips plate immersed in liquid xenon. Both were observed in an intense non-uniform electric field in the vicinity of 2-$\mu$m narrow anode strips deposited, with a 2~mm pitch, on a semiconductive glass substrate (S8900), with a cathode film on its backside. An initial light yield of $\sim$460 VUV photons per drifting electron was measured, which degraded within tens of minutes stabilizing at (27.0~$\pm$~3.1)~photons per electron. The electroluminescence was accompanied by electron multiplication with an estimated charge gain $<$10. Further investigations are necessary to understand and mitigate the light yield degradation phenomenon. We expect other substrate materials, including VUV-transparent ones, to provide large stable photon yields, compatible with our model predictions. The VCC configuration has demonstrated great potential in single-phase noble-liquid detectors, particularly for dark-matter searches, neutrino physics and other fields.

We study the covariant diffusion and drift of massless particles on the light cone within the context of quantum gravity phenomenology. Unlike modified dispersion relations that violate Lorentz invariance and grow with frequency, this model introduces a stochastic correction to the massless geodesic equation while preserving Lorentz invariance, and is dominant at lower frequencies due to the larger spacetime support of long-wavelength modes. The effect is phenomenologically described by just two diffusion and drift parameters, $\kappa_1$ and $\kappa_2$, whose values are already constrained by measurements of the CMB blackbody spectrum. We show that a direct measurement and characterization of a gravitational wave (GW) background frequency spectrum can improve bounds on these diffusion and drift parameters by over 12 orders of magnitude compared to those from the CMB. In particular, we find that detecting a GW background sourced by realistic models of first-order phase transitions or primordial black holes (PBH) with LISA can constrain the parameters down to a value of $\kappa_1,\,\kappa_2\lesssim 10^{-56}\,\text{kg}\,\text{m}^2\text{s}^{-3}$.

A black hole is expected to end its lifetime in a cataclysmic runaway burst of Hawking radiation, emitting all Standard Model particles with ultra-high energies. Thus, the explosion of a nearby primordial black hole (PBH) has been proposed as a possible explanation for the $\sim 220$ PeV neutrino-like event recently reported by the KM3NeT collaboration. Assuming a PBH origin, we find that the source would need to lie at a distance of approximately $4 \times 10^{-5}$ pc, i.e., within the Solar System, to produce the observed event. At such proximity, the resulting flux of gamma-rays and cosmic rays would be detectable at Earth. By incorporating the time-dependent field of view of gamma-ray observatories, we show that LHAASO should have recorded on the order of ${\cal O}(10^8)$ events between fourteen and seven hours prior to the KM3NeT detection. IceCube should also have detected about 100 events at the time of the burst. The absence of any such multi-messenger signal, particularly in gamma-ray data, strongly disfavors the interpretation of the KM3-230213A event as arising from evaporation in a minimal four-dimensional Schwarzschild scenario.

We present a systematic study of likelihood functions used for Stochastic Gravitational Wave Background (SGWB) searches. By dividing the data into many short segments, one customarily takes advantage of the Central Limit Theorem to justify a Gaussian crosscorrelation likelihood. We show, with a hierarchy of ever more realistic examples, beginning with a single frequency bin and one detector, and then moving to two and three detectors with white and colored signal and noise, that approximating the exact Whittle likelihood by various Gaussian alternatives can induce systematic biases in the estimation of the SGWB parameters. We derive several approximations for the full likelihood and identify regimes where Gaussianity breaks down. We also discuss the possibility of conditioning the full likelihood on fiducial noise estimates to produce unbiased SGWB parameter estimation. We show that for some segment durations and bandwidths, particularly in space-based and pulsar-timing arrays, the bias can exceed the statistical uncertainty. Our results provide practical guidance for segment choice, likelihood selection, and data-compression strategies to ensure robust SGWB inference in current and next-generation gravitational wave detectors.