Papers for Wednesday, Aug 13 2025

Astrophysical high-energy (TeV-PeV) neutrinos were first discovered in 2013, but their origin remains largely unknown. Here we present SN 2023uqf, a supernova found in coincidence with high-energy neutrino IC231004A, as part of a systematic optical follow-up program with the Zwicky Transient Facility. SN 2023uqf had a luminous and rapidly-evolving lightcurve, and spectroscopic observations indicated that the source was a Type Ibn supernova. Spectroscopic signatures confirm ongoing interaction between the supernova ejecta and a dense circumstellar medium, as expected for high-energy neutrino production in a core-collapse supernova. Given the rare nature of Type Ibn supernovae, SN 2023uqf is unlikely to have been discovered by chance over the course of our program (p=0.3%). Our discovery of SN 2023uqf provides the first observational evidence to support long-held theories that interacting supernovae can serve as cosmic hadron accelerators.

Our observations with the James Webb Space Telescope have made the remarkable discovery of strong gravitational lensing arcs from XLSSC 122 ($z=1.98$) - setting the record for the most distant galaxy cluster that exhibits strong lensing. The discovery of giant arcs enables a strong-lensing analysis and a measurement of the concentration of the dark matter halo. We perform a strong-lensing analysis of the cluster and measure the radial projected mass density profile. Our measurements reveal an exceptionally high concentration in the core of XLSSC 122. A Navarro--Frenk--White profile fit to the inner 100 kpc estimates the concentration to be $6.3\pm0.5$. The high concentration of XLSSC 122 contributes to the emerging picture that massive structure formation in the early universe may proceed more rapidly than standard models suggest. We estimate the mass within 100 kpc to be $M$($R<$100 kpc) = $6.5\pm0.7\times10^{13}$ M$_\odot$. Our mosaic images are made public at this https URL .

The metal-poor stars of a galaxy offer insights into that galaxy's early formation processes and accretion history. Here, we investigate whether the metal-poor stars of our Milky Way galaxy exhibit any characteristic trends in Galactocentric distance versus chemical abundances -- i.e. in the space of $r_{\rm GC}$ vs. [Fe/H] and $r_{\rm GC}$ vs. [X/Fe] -- and if yes, then what is their implication for Galaxy formation. We combine the datasets of APOGEE DR17 and $\textit{Gaia}$ DR3, where the former provides stellar abundances and the latter provides stellar parallaxes. We analyze bright ($G<13$) and metal-poor ([Fe/H]$<-1.2$) stars located far from the disk ($|z|\geq1$ kpc), and explore a total of $19$ abundances. We find that $9$ different abundances exhibit a drastic transition in their distribution near the Solar radius $r_{\rm GC}=8$ kpc. This trend is very unlikely to be related to radial migration, as our metal-poor sample does not contain any disk star. We also analyze the Gaia-Sausage/Enceladus stars, which is a dominant metal-poor population of the Galaxy, and find that it alone cannot account for this trend. This suggests that the Milky Way's metal-poor populations inside and outside the Solar radius likely originated from distinct chemical enrichment scenarios and formation processes.

Observations indicate that high-redshift galaxies undergo episodic star formation bursts, driving strong outflows that expel gas and suppress accretion. We investigate the consequences for metal and dust content of galaxies at $z\geq\!5$ using our semi-analytical model, ASHVINI. We track gas-phase and stellar metallicities $(Z_\text{g}, Z_\star)$ and dust mass $(M_{\rm d})$ in dark matter haloes spanning $M_{\rm h} = 10^6 - 10^{11}\,M_\odot$, comparing continuous and bursty star formation scenarios, which reflect underlying assumptions of instantaneous and delayed feedback, and we allow for metallicity-dependent feedback efficiency. Delayed feedback induces oscillations in $Z_{\rm g}$ and $Z_\star$, with $Z_{\rm g}$ declining sharply at low stellar and halo masses. This decline shifts to higher stellar and halo masses as the redshift decreases. Reionization introduces significant scatter, producing an upturn followed by rapid $Z_{\rm g}$ decline. Metallicity-dependent feedback moderates this decline at $z=7-10$, flattening the $Z_{\rm g}$-mass relation to $\simeq 0.03 - 0.04\,Z_\odot$. Dust production tracks $Z_{\rm g}$ but is sensitive to burst history, causing delayed enrichment. Our results show that burst-driven feedback decouples $Z_{\rm g}$ and $Z_\star$, imprints intrinsic scatter in mass-metallicity relations, and delays dust growth. These effects are strongest in low-mass halos $(M_{\rm h}\sim 10^7\,M_\odot)$, where shallow potentials amplify the impact of feedback. Our results are consistent with recent hydrodynamical and semi-analytical simulations and provides context for interpreting JWST metallicity and dust measurements, highlighting the importance of episodic star formation in early galaxy chemical evolution.

We examine the statistics of main-sequence / main-sequence, main-sequence / white-dwarf and white-dwarf / white-dwarf wide binaries at 10^2.5-10^4 AU separations in Gaia data. For binaries containing a white dwarf, we find a complex dependence of the wide binary fraction on the white dwarf mass, including a steep decline as a function of mass at >0.6Msun. Furthermore, we find that wide binaries containing white dwarfs have significantly lower eccentricities than main-sequence binaries at the same separations. To model these observations, we compute the effects of post-main-sequence mass loss on the orbital parameters of wide binaries in all regimes of timescales, from secular to impulsive, and incorporate this dynamics in a population synthesis model. We find that adiabatic expansion of the orbits in binaries with slow enough evolutionary processes is the most likely explanation for the puzzling eccentricity distribution of white dwarf wide binaries. The steeply declining white dwarf binary fraction as a function of mass requires that the timescale for mass loss must be significantly shorter for high-mass stars (10^3-10^4 years) than for the low-mass ones. We confirm previous studies that suggested that recoil in the range 0.25-4 km/s is required to explain the observed distribution of separations of white dwarf wide binaries. Finally, for low-mass white dwarfs (<0.5Msun), we see interesting signatures of their formation due to close binary evolution in their wide binary statistics. Our observations and modeling provide a novel dynamical constraint on the mass-loss stages of stellar evolution that are difficult to probe with direct observations.

In Pulsar Timing Array (PTA) data analysis, noise is typically assumed to be Gaussian, and the marginalized likelihood has a well-established analytical form derived within the framework of Gaussian processes. However, this Gaussianity assumption may break down for certain classes of astrophysical and cosmological signals, particularly for a gravitational wave background (GWB) generated by a population of supermassive black hole binaries (SMBHBs). In this work, we present a new method for testing the presence of non-Gaussian features in PTA data. We go beyond the Gaussian assumption by modeling the noise or signal statistics using a Gaussian mixture model (GMM). An advantage of this approach is that the marginalization of the likelihood remains fully analytical, expressed as a linear combination of Gaussian PTA likelihoods. This makes the method straightforward to implement within existing data analysis tools. Moreover, this method extends beyond the free spectrum analysis by producing posterior probability distributions of higher-order moments inferred from the data, which can be incorporated into spectral refitting techniques. We validate the model using simulations and demonstrate the sensitivity of PTAs to non-Gaussianity by computing the Bayes factor in favor of the GMM as a function of the injected excess moments. We apply the method to a more astrophysically motivated scenario where a single SMBHB is resolved on top of a Gaussian GWB and show that significant non-Gaussianities are introduced by the individual source. Finally, we test our model on a realistic GWB generated from a simulated population of SMBHBs.

We combine absolute astrometry from Hipparcos and Gaia with archival radial velocities from the Keck/HIRES and ESO/HARPS spectrographs, as well as relative astrometry (when available), to derive masses and orbits for 156 companions around main-sequence stars, including 111 stellar companions, 12 brown dwarfs, and 33 planets. Although this sample is not compiled for occurrence-rate statistics due to systematic biases in non-uniform target selection and varied observing strategies, we nonetheless clearly detect the Brown Dwarf desert in the distribution of companion masses (as well as in mass ratio), out to separations of more than 10 AU. This work also enables a validation of Gaia DR3 non-single-star solutions by predicting Gaia's measured Right Ascension and Declination acceleration terms. For stars with Gaia astrometric acceleration solutions, we find qualitative agreement with Gaia DR3 results. Our predicted accelerations agree with the Gaia DR3 values overall, showing a median offset of 1.85 sigma, with a tail extending to about 10 sigma. These residuals suggest modestly underestimated uncertainties, broadly consistent with previous results for parallaxes and proper motions. Three of our systems have full Gaia orbital fits; however, their true orbital periods are long and all three Gaia solutions are spurious. Gaia DR4 will provide individual astrometric measurements and enable more detailed and extensive investigations of accelerating and orbital fits.

Tidal disruption events are rare and diverse transients that occur when a star is torn apart by a supermassive black hole and accreted, which can result in a supersoft X-ray thermal transient. Here, we present nine tidal disruption event (TDE) candidates identified in eROSITA-DE Data Release 1 through a novel search for such supersoft sources. We select candidates by comparing the catalogued count rates in several combinations of bands and evaluate the nature of selected sources to produce our sample, among which five are entirely new X-ray TDE candidates. All our candidates' X-ray spectra are consistent with soft thermal emission and we show them to have faded through additional Swift observations and catalogued data. We investigate publicly available data from ground- and space-based telescopes and find two of our sources have optical counterparts and four sources show flaring in their NEOWISE IR light curves. The high proportion of our sources with IR flares compared to optically selected TDE samples could suggest a link between supersoft X-ray spectra and IR counterparts. We fit the IR light curves with a model of a spherical dust shell heated by the TDE and find these results to be broadly consistent with those of other TDEs with IR counterparts. Finally, we examine the host galaxies and show them to be similar to the general TDE host population.

Strong gravitational lensing acts as a cosmic telescope, enabling the study of the high-redshift universe. Astronomical interferometers, such as the Atacama Large Millimeter/submillimeter Array (ALMA), have provided high-resolution images of strongly lensed sources at millimeter and submillimeter wavelengths. To model the mass and light distributions of lensing and source galaxies from strongly lensed images, strong lens modeling for interferometric observations is conventionally performed in the visibility space, which is computationally expensive. In this paper, we implement an image-plane lens modeling methodology for interferometric dirty images by accounting for noise correlations. We show that the image-plane likelihood function produces accurate model values when tested on simulated ALMA observations with an ensemble of noise realizations. We also apply our technique to ALMA observations of two sources selected from the South Pole Telescope survey, comparing our results with previous visibility-based models. Our model results are consistent with previous models for both parametric and pixelated source-plane reconstructions. We implement this methodology for interferometric lens modeling in the open-source software package lenstronomy.

We study the efficiency of high-e migration as a pathway for Hot Jupiter formation in the dense globular cluster 47 Tuc. Gravitational N-body simulations are performed to investigate the orbital evolution of star-planet systems due to dynamical stellar perturbations. Planetary systems that have been scattered into orbits of sufficiently high eccentricity can undergo tidal circularisation, with Hot Jupiter formation being one possible stopping condition. We also account for the possibility of (i) ionisation due to high-energy encounters, (ii) tidal disruption of the planet by tidal forces inside the Roche limit and (iii) Warm Jupiter formation. The orbital evolution of a population of cold Jupiter progenitors, with initial semi-major axes between 1-30 au, is simulated over 12 Gyr using a simplified dynamical model of 47 Tuc. Our computational treatment of dynamical encounters yields an overall HJ occurrence rate of F_HJ = 5.9 x 10^-4 per cluster star (a 51 per cent enhancement relative to the analytic baseline). The probability of Hot Jupiter formation is highest in the core and falls off steeply beyond a few parsecs from the centre of the cluster, where the stellar density is too low to drive efficient eccentricity diffusion. The code can be found here: this https URL.

Aims. We will test the statistical significance of meteorite-dropping fireballs and NEA clustering using the DN similarity function based on four geocentric quantities (U, theta, phi, and lambda). Methods. We calculated the cumulative similarity found between 46 meteorite falls, 535 potential meteorite-dropping fireballs, 20,516 NEAs maintained by NEODyS-2, along with 34,836 NEAs maintained by NASA/JPL HORIZONS. Statistical significance was estimated by either: (1) Kernel Density Estimation-based method to estimate the sporadic background distribution to draw random samples, or (2) applying a uniform random solar longitude (lambda). Each comparison to the synthetic sporadic population is repeated to estimate the 3-sigma region for which the cumulative similarity distribution is consistent with random association levels. Results. The observed DN cumulative similarity distribution between 46 instrumentally observed meteorite falls, 535 potential meteorite-dropping fireballs, and over 30k NEAs radiants (estimated using 6 different radiant methods) reveals no statistically significant excess of similarity between the populations consistent with streams. Conclusions. Based on nearly 600 fireball observations, there is no statistically significant clustering between meteorite falls and NEAs using geocentric impact parameters. If some meteorites arrive in streams, they make up less than ~0.1% of all falls. Recent asteroid or meteoroid physical processes could still explain features found in meteorites, but this activity is not producing distinguishable orbital streams or pairs.

The nearby TRAPPIST-1 system, with its seven small rocky planets orbiting a late-type M8 star, offers an unprecedented opportunity to search for secondary atmospheres on temperate terrestrial worlds. In particular, the 0.8 Earth-radii planet TRAPPIST-1 d lies at the edge of the habitable zone (equilibrium temperature ~262 K). Here we present the first 0.6-5.2 micron NIRSpec/PRISM transmission spectrum of TRAPPIST-1 d from two transits with JWST. We find that stellar contamination from unocculted bright heterogeneities introduces 500-1,000 ppm visit-dependent slopes, consistent with constraints from the out-of-transit stellar spectrum. Once corrected, the transmission spectrum is flat within $\pm$100-150 ppm, showing no evidence for a haze-like slope or molecular absorption despite NIRSpec/PRISM's sensitivity to CH4, H2O, CO, SO2, and CO2. Our observations exclude clear, hydrogen-dominated atmospheres with high confidence (greater than 3$\sigma$). We leverage our constraints on even trace amounts of CH4, H2O, and CO2 to further reject high mean molecular weight compositions analogous to Titan, a cloud-free Venus, early Mars, and both Archean Earth and a cloud-free modern Earth scenario (greater than 95% confidence). If TRAPPIST-1 d retains an atmosphere, it is likely extremely thin or contains high-altitude aerosols, with water cloud formation at the terminator predicted by 3D global climate models. Alternatively, if TRAPPIST-1 d is airless, our evolutionary models indicate that TRAPPIST-1 b, c, and d must have formed with less than approximately 4 Earth oceans of water, though this would not preclude atmospheres on the cooler habitable-zone planets TRAPPIST-1 e, f, and g.

The discovery of thousands of exoplanets and the emergence of telescopes capable of exoplanet atmospheric characterization have intensified the search for habitable worlds. Due to selection biases, many exoplanets under study are planets deemed inhospitable because their surfaces are too warm to support liquid water. We propose that such planets could still support life through ionic liquids: Liquid salts with negligible vapor pressure that can persist on warm planets with thin atmospheres, where liquid water cannot. Ionic liquids have not previously been considered as naturally occurring substances, and thus have not been discussed in planetary science. We demonstrate in laboratory experiments that ionic liquids can form from planetary materials: Sulfuric acid combined with nitrogen-containing organic molecules. Sulfuric acid can be volcanic in origin, and organic compounds are commonly found on planetary bodies. The required planetary surface is water-depleted and must support sulfuric acid transiently in liquid phase to dissolve organics, followed by evaporation of excess liquid, conditions spanning approximately 300 K at 10^-7 atm to 350-470 K at 0.01 atm. Because ionic liquids have extremely low vapor pressures, they are not prone to evaporation, allowing small droplets or pools to persist without ocean-like reservoirs. Ionic liquids' minuscule vapor pressure at room temperature suggests possible stability on planets with negligible atmospheres, shielded by magnetic fields or rock crevices against harsh cosmic radiation. Ionic liquids can stably dissolve enzymes and other biomolecules, enabling biocatalysis and offering a plausible solvent for life, broadening the definition of habitable worlds.

We consider the evolution of linear matter perturbations in the context of the standard cosmological model ($\Lambda$CDM) and a phenomenological modified gravity model. We use the physics-informed neural network (PINN) bundle method, which allows to integrate differential systems as an alternative to the traditional numerical method. We apply the PINN bundle method to the equation that describes the matter perturbation evolution, to compare its outcomes with recent data on structure growth, $f\sigma_8$. Unlike our previous works, we can calculate a bound on the error of this observable without using the numerical solution of the equation. For this, we use a method developed previously by ourselves to calculate an exact bound on the PINN-based solution using only the outcomes of the network and its residual. On the other hand, the use of an updated data set allows us to obtain more stringent constraints on the plane $\Omega_m-\sigma_8$ than previous works.

Moment-based estimation filters have successfully aided spacecraft navigation for decades. However, future missions plan to venture into deep-space regimes with significant round-trip light-time telecommunication delays, operate in unstable, quasi-periodic orbits, and perform highly precise, low-altitude flybys of outer planet moons. These complex trajectories may necessitate ensemble-based filters for accurate estimation over realistic measurement cadences. To mitigate the inherent risk associated with testing novel navigation software, ensemble filters must be accurate, efficient, and robust. Grid-based, Bayesian Estimation Exploiting Sparsity, a high-dimensional Godunov-type finite volume method that propagates the full probability distribution function, demonstrates strong overall performance across all these criteria when compared with the contemporary landscape of filters. These qualities are exhibited via a Bayesian investigation in which the state uncertainty of a Saturn-Enceladus Distant Prograde Orbit is propagated, incorporating infrequent, nonlinear measurement updates. Along with root mean square error, we use the Bhattacharyya coefficient, a non-normal metric for measuring the dissimilarity between distributions, and the Effective Sampling Size, a measure of particle degeneracy, to quantitatively ascertain that in this application, Grid-based, Bayesian Estimation Exploiting Sparsity outperforms the other ensemble filters assessed, though it comes at a nontrivial computational cost.

Observations of intergalactic absorbers in the Local Group suggest the existence of a velocity dipole in the general barycentre--antibarycentre direction which can be interpreted as evidence of a general flow of material towards the group's centre of mass. In this work, we study the kinematics of gas in the Local Group using one of the high-resolution realisations of the {\sc Hestia} simulations with a particular focus on the evidence left by different ionic species. Our simulation includes the correct cosmography for a region similar to the Local Group and a relative radial velocity between the candidate Milky Way and Andromeda galaxies consistent with the observed one. We examine the distribution and kinematics of six ionic species (H\,{\sc i}, C\,{\sc iv}, Si\,{\sc iii}, O\,{\sc vi}, O\,{\sc vii} and O\,{\sc viii}) and their imprints on synthetic sky maps constructed from the reference frames commonly used by observers. Our results indicate the presence of such a dipole for gas outside the Milky Way halo, favouring a paradigm in which the Milky Way is moving against the gas in the direction of the barycentre, while moving away from it in the opposite direction. This pattern is clearer for the higher oxygen ions, which preferentially trace hot gas. On the other hand, we observe a slight asymmetry in the pressure profiles in both directions, indicating higher pressures in the inner regions of the Local Group.

Deep and wide-field near-infrared (NIR) surveys have recently discovered and confirmed ultramassive galaxies (UMGs; $\log (M_{\star}/M_{\odot})>11$) spectroscopically at high redshift. However, most are characterized using only ultraviolet (UV)-to-NIR photometry, offering limited insight into obscured star formation and active galactic nucleus (AGN) activity. In this work, we add ten far-infrared (FIR)-to-radio passbands to the existing UV-to-NIR catalogs for two spectroscopically confirmed UMGs from the MAGAZ3NE survey, COS-DR3-195616 ($z_{\rm spec} = 3.255$) and COS-DR1-209435 ($z_{\rm spec} = 2.481$). Utilizing the full UV-to-radio photometry, we revise our earlier UV-NIR-based interpretation of the nature of these galaxies. While both were previously identified as quiescent, our analysis reveals that 195616 is an unobscured galaxy undergoing quenching, and 209435 is a heavily obscured, actively star-forming UMG. We find that 195616 has already depleted most of its molecular gas and is expected to experience minimal future stellar mass growth. In contrast, 209435 contains a substantial molecular gas reservoir and has a prolonged depletion timescale. It is anticipated to increase 0.34 dex in stellar mass, reaching a stellar mass of $\log (M_{\star}/M_{\odot})$ = 11.72 over the next 0.72 Gyr. We present multi-pronged evidence for AGN activity in both UMGs. Our findings support a scenario where AGN feedback in 195616 may have contributed to gas depletion during quenching, while 209435 continues to form stars despite hosting an obscured AGN, suggesting feedback has not yet suppressed star formation. Our work shows the importance of FIR-to-radio observations for accurately inferring the nature and properties of galaxies at $z\gtrsim3$.

We present observations of \epseri~with the JWST/NIRCam coronagraph aimed at imaging planets orbiting within this system. In particular, these observations targeted (1) the Jupiter-like planet, first detected orbiting at 3.5 AU with radial velocity observations, and (2) the planet postulated to be responsible for carving the edges of \epseri's outer ring, expected to orbit at 40-50 AU. However, no point sources were detected at a statistically significant level. We report new, improved upper limits at 4 $\mu$m: $\sim$1e-7~contrast at 1\arcsec, and $\sim$2e-8~beyond 5\arcsec. The latter contrast limit precludes Saturn-mass planets at separations $>$16~AU given current models. We also report upper limits for \epseri's disk emission at 4 $\mu$m. While the radial surface brightness profile shows no evidence of emission, we detect a 1-$\sigma$ surface brightness signal on the east side of the system, consistent with forward scattering emission expected for \epseri's disk inclination. Finally, we evaluate the performance of the 3-roll observation strategy, which was first employed in these observations: the gains in contrast are modest, with 20-30\% improvements with respect to the conventional 2-roll strategy.

We present a set of new smoothing kernels for smoothed particle hydrodynamics (SPH) that improve the convergence of the method without any additional computational cost. These kernels are generated through a linear combination of other SPH kernels, combined with an optimization strategy to minimize the error in the Gresho-Chan vortex test case. To facilitate the different choices in gradient operators for SPH in the literature, we perform this optimization for both geometric density average force SPH (GDSPH) and linear-corrected gradient SPH (ISPH). In addition to the Gresho-Chan vortex, we also perform simulations of the hydrostatic glass, Kelvin-Helmholtz instability, and the Sod shocktube case. At low neighbour numbers (< 128), there is a significant improvement across the different tests, with the greatest impact shown for GDSPH. Apart from the popular Wendland kernels, we also explore other positive-definite kernels in this paper, which include the "missing" Wendland kernels, Wu kernels, and Buhmann kernels. In addition, we also present a method for producing arbitrary non-biased initial conditions in SPH. This method uses the SPH momentum equation together with an artificial pressure, combined with a global and local relaxation stage to minimize local and global errors.

The IceCube Neutrino Observatory studies cosmic-ray initiated extensive air showers (EASs) using the IceTop surface array, which is sensitive to the electromagnetic component and low-energy ($\sim$ GeV) muonic component of EASs. The contribution from the two components is reconstructed on an event-by-event basis by simultaneously fitting separate lateral distribution functions (LDFs) for both the electromagnetic and muonic components of each shower. In this work, we demonstrate the ability of the two-component LDF reconstruction to recreate the muon distribution in IceTop accurately. The parameters characterizing the reconstructed muonic LDF can vary significantly based on the choice of hadronic interaction model. Thus, the dependence of the reconstructed muon LDF and other parameters on the hadronic interaction models is investigated.

Spectator fields which provide additional tensor degrees of freedom, on top of the standard metric tensor perturbations, can produce significant amounts of gravitational waves (GWs). Employing the effective field theory approach for spin-2 fields, we find a universal prediction that linear mixing between the metric and extra tensor modes inevitably induces oscillatory features in the GW spectrum, reminiscent of the so-called neutrino oscillation. Moreover, parity-violating operators in the spin-2 sector can imprint chiral signatures on the resulting GW background. We consider a concrete scenario in which the spin-2 field generates observable chiral GWs with characteristic oscillatory patterns. These results provide a model-independent characterization of the key signatures and observational implications of such scenarios which can be detected with future GW detectors.

Accurately assessing image source completeness is critical for interpreting measurements on telescope data. Using the Wide Field Camera 3 (WFC3) and Advanced Camera for Surveys (ACS) data from the Hubble Space Telescope ($HST$) archival project "SKYSURF", we model galaxy completeness as a function of the exposure time and background of an image. This is accomplished by adding simulated objects with varying magnitudes and sizes into these images, and determining the detection rate for each set of parameters. The fifty percent completeness results are then compared to the Exposure Time Calculator (ETC), in order to assess the differences between the STSCI ETC and our analysis of the archival data. Ultimately, we find that, for extended galaxies, the ETC predicts a 1-2 magnitudes fainter completeness limit than our data. We believe the difference is due to the ETC's flat surface brightness profiles being less accurate at predicting for extended sources compared to our more realistic profiles.

The classical polyhedral model is one of the most accurate methods currently used to represent the gravitational field of irregularly shaped bodies. However, it assumes a homogeneous density distribution, which may not accurately reflect the internal composition of real objects. This study aims to analyze the effects of the internal structure of asteroid (21) Lutetia on gravitational potential modeling by considering a three-layered composition with distinct densities. The gravitational approach adopted in this study is the Potential Series Expansion Method (PSEM), represents models the body as a polyhedron and decomposes it into tetrahedral elements to estimate of the total potential around the asteroid. This estimation involves summing the contributions of each tetrahedron using a direct triple integral over its volume. Although this method does not achieve the same level of accuracy as the classical polyhedral approach, it offers a reasonable degree of precision, expresses the potential in analytical form, significantly reduces computational time, and, due to the simplified algebraic manipulation of the potential, facilitates the analysis of the asteroid's internal structural composition.

Supercritical accretion onto compact objects is expected to drive optically thick winds, resulting in observed X-ray emission as a function of viewing angle. However, their optical emission, either from the outer accretion disk or companion surface tends to be nearly isotropic. Based on a sample of luminous and very soft X-ray sources that are argued to be supercritical accretion systems viewed close to edge-on, we identified the optical counterparts for some of them and compared the optical properties with those of ultraluminous X-ray sources (ULXs), which are supposed to be supercritical accretion systems viewed close to face-on. The optical luminosity is found in a wide range, with the absolute visual magnitude ranging from dimmer than -1.2 in some sources to about -7 in one case. Most sources show a power-law like spectrum while four of them display a blackbody shape. One of them shows an optical spectrum resembling a B type main sequence, suggesting that it may be a Be white dwarf system. Strong variability in flux at timescales as short as 10 days are revealed, indicating that some of these sources are powered by accretion onto compact objects. These suggest that the luminous and very soft X-ray sources in nearby galaxies have a diverse population, and some of them are indeed consistent with emission from supercritical accretion, with consistent optical magnitudes and colors. Future optical spectroscopic observations are needed to further constrain their natures.

GW231123 represents the most massive binary-black-hole merger detected to date, lying firmly within, or even above, the pair-instability mass gap. The component spins are both exceptionally high ($a_1 = 0.90^{+0.10}_{-0.19}$, $a_2 = 0.80^{+0.20}_{-0.51}$), which is difficult to explain with repeated mergers. Here we show that the black hole spin vectors are closely aligned with each other while significantly tilted relative to the binary's orbital angular momentum, pointing to a common accretion-driven origin. We examine astrophysical formation channels capable of producing near-equal, high-mass, and mutually aligned spins consistent with GW231123 -- particularly binaries embedded in AGN disks and Pop~III remnants, which grew via coherent misaligned gas accretion. We further argue that other high-mass, high-spin events, e.g., GW190521 may share a similar evolutionary pathway. These findings underscore the critical role of sustained, coherent accretion in shaping the most extreme black hole binaries.

We present a comprehensive spectro-temporal analysis of GRS $1915+105$ observed with AstroSat during June, $2017$. A detailed study of the temporal properties reveals the appearance of an `unknown' variability class ($\tau$) during $\rho \rightarrow \kappa$ class transition of the source. This new `unknown' class ($\tau$) is characterized by the irregular repetition of low count `dips' along with the adjacent `flare' like features in between two successive steady count rate durations, resulting in uniform `$C$' shaped distribution in the color-color diagram. A detailed comparative study of the variability properties between the $\tau$ class and other known variability classes of GRS $1915+105$ indicates it as a distinct variability class of the source. Further, we find evidence of the presence of possible HFQPO features at $\sim 71$ Hz with quality factor $\sim 13$, rms amplitude $\sim 4.69\%$, and significance $3\sigma$, respectively. In addition, a harmonic-like feature at $\sim 152$ Hz is also seen with quality factor $\sim 21$, rms amplitude $\sim 5.75\%$ and significance $\sim 4.7\sigma$. The energy-dependent power spectral study reveals that the fundamental HFQPO and its harmonic are present in $3-15$ keV and $3-6$ keV energy ranges, respectively. Moreover, the wide-band ($0.7-50$ keV) spectral modelling comprising of thermal Comptonization component indicates the presence of a cool ($kT_{\rm e}\sim 1.7$ keV) and optically thick (optical depth $\sim 14$) Comptonizing `corona', which seems to be responsible in regulating the HFQPO features in GRS $1915$+$105$. Finally, we find the bolometric luminosity ($L_{\rm bol}$) to be about $42\% L_{\rm Edd}$ within $1-100$ keV, indicating the sub-Eddington accretion regime of the source.

We study a catalogue of over 130 emission-line galaxies with matched near infra-red (NIR) and optical spectra, where we examine the relationship between the respective nuclear activity classifications, diagnosed by the flux ratios of emission lines. We match the standard NIR classification with four different optical classifications. While there is a broad agreement between the two regimes, there are mismatches and overlaps caused either by aperture effects and/or NIR radiation penetrating obscuring dust and "seeing deeper" into the nuclear region, thus exposing AGN activity. We examine the relationship between the equivalent widths (EW) of H$\alpha$ and Pa$\beta$, as well as the ratios [N II]/H$\alpha$ vs. [Fe II]/Pa$\beta$, and find reasonable correlations. We thus propose a new diagnostic (EW of Pa$\beta$ with Fe - WPF) in the NIR (analogous to the WHaN classification), using the [Fe II]/Pa$\beta$ flux ratio and the EW of the Pa$\beta$ line. We show, within the limitations of the catalogue size, that the regions of the standard NIR diagram can be reasonably replicated in this new scheme. This diagnostic has the advantage that only one wavelength range needs to be observed, thus being economical with telescope time.

We examined archived observations of 2,821 stars taken by the high-resolution ESO HARPS spectrograph to search for potential narrow-band laser emissions from extraterrestrial sources. From one observation of each star, our search algorithm identified a total of 285 spectral peaks with line widths slightly larger than the instrument's point-spread function. After eliminating false positives (including cosmic rays, instrumental artifacts, and terrestrial airglow lines, we identified 8 sources worthy of follow-up observations. We then analyzed all 1,835 additional observations of these follow-up targets, looking for recurring signals. We found 1 additional unexplained candidate in this followup search, but no candidate spikes which repeated at the same wavelength as one of the initial candidates at a later time. Further analysis identified one candidate as a likely faint airglow line. The remaining seven candidates continued to defy all false positive categories, including interference by LiDAR satellites and adaptive optics lasers from neighboring observatories. However, observations of other stars on the same night showed identical spectral spikes (in the telescope's reference frame) for four of these seven candidates -- indicating an as-yet unknown terrestrial source. This leaves 3 final candidates which currently defy the prosaic explanations examined thus far, show no indication of a terrestrial origin and therefore warrant further investigation. Two of these three candidates originate from M-Type stars and one of them originates from an oscillating red giant, so follow-up work will need to disentangle natural astrophysical stellar processes from potential SETI sources.

We explore a cosmological framework in which a Gauss-Bonnet (GB) coupled scalar field, acting as dark energy, interacts with a fermionic dark matter field through a coupling obtained from the point of view of particle physics. This setup is inspired by string/M-theory, and two representative scalar field potentials are investigated: exponential and power-law. A distinctive feature of the GB-coupled models is their potential to alter the propagation speed of gravitational waves (GWs), a property with significant implications in light of recent multi-messenger astrophysical observations. To account for this, we analyze models under two scenarios: one where the GW speed differs from that of light and the other where they are equal, but all consistent with current observational constraints. The dynamical evolution of the system is investigated by reformulating the field equations into an autonomous dynamical system, enabling a detailed analysis of the Universe's long-term behavior, including the radiation-, matter- and dark energy-dominated epochs. We constrain the model parameters using a broad set of recent observational data, including mock high-redshift measurements from the Roman Space Telescope. Our findings indicate that both potentials yield cosmologies that are in excellent agreement with current data, closely tracking the expansion history predicted by the standard \(\Lambda\)CDM model, while still allowing room for subtle deviations that could be tested by future observations.

We present a kinematic study of young stars in Messier 16 (M16) using the Gaia Data Release 3 and high-resolution spectra. A total of 345 stars are selected as genuine members using the published lists of X-ray, infrared sources, and early-type stars as well as the Gaia data. There is severe differential reddening across this region and the reddening law of the intracluster medium appears abnormal. The distance to M16, derived from the parallaxes of the members, is about 1.7 kpc. The ages of members, estimated by comparing their color-magnitude diagram with theoretical isochrones, range from 1 Myr to 4 Myr. This star-forming region is composed of an open cluster (NGC 6611) and a distributed population. This cluster shows a clear pattern of expansion and rotation. Some of the distributed population are spatially associated with the gas pillars located at the ridge of H II bubble. In particular, several stars moving away from the cluster are physically associated with the northeastern pillar. In addition, their younger ages support the idea that the formation of these stars was triggered by the feedback from massive stars in NGC 6611. On the other hand, the other stars do not show systematic radial or stream motions; therefore, they likely formed through spontaneous star formation events. We discuss the formation of young stars in the context of cluster expansion, spontaneous star formation, and feedback-driven star formation, and suggest that all of these mechanisms possibly contributed to their formation.

The lithium-dip observed in mid-F dwarfs remains a long-standing challenge for stellar evolution models. We present high-precision stellar parameters and A(Li) for 22 new comoving pairs, primarily located on the hotter side of the Li-Dip. Combined with pairs from the C3PO catalog, our sample includes 124 stars with Teff between 6000 and 7300 K, encompassing and extending slightly beyond the Li-Dip. Among them, 49 comoving pairs (98 stars) have both components within the temperature range of interest. Using this expanded set of comoving pairs observed with high-resolution spectroscopy, we show that rotational spin-down is the dominant process responsible for Li depletion in the Li-Dip. First, within comoving pairs, the star with v sin i > 12 km/s shows higher A(Li) than its more slowly rotating companion within the Li-Dip, indicating that rotation-dependent mixing drives lithium depletion. Second, we observe a correlation between A(Li) and v sin i: fast rotators retain higher A(Li) with less scatter, while slow rotators show lower A(Li) and greater dispersion. Third, among slow rotators, A(Li) varies widely, suggesting that differences in initial rotation rates and spin-down histories influence how much Li is depleted. Some stars may have formed as fast rotators and spun down rapidly, leading to more Li depletion, while others may have started as slow rotators and retained more of their initial Li. These results demonstrate that rotational induced mixing plays an important role in shaping the Li-Dip beyond the effects of stellar age and mass.

We investigate two barred galaxies with nuclear structures, NGC 6951 and NGC 7716, to examine whether they host slow bars. Using Gemini/GMOS long-slit spectroscopy, we calculate the bar pattern speed with the Tremaine-Weinberg method and detect kinematically decoupled nuclear disks in both galaxies. We also measure the bar length and strength using Pan-STARRs images and identify a nuclear ring in NGC 6951 and a nuclear bar in NGC 7716 from HST/PC images. Our results indicate that NGC 6951 hosts a slow, long, and strong bar, which likely evolved through interactions with the dark matter halo and contributed to the formation of both the nuclear disk and ring. We also find hints of a rapidly rotating oval structure within the primary bar, although it is not clearly seen in the imaging data. In contrast, the primary bar in NGC 7716 is too weak to be classified as a barred galaxy, while its nuclear disk and nuclear bar are unusually large, possibly due to tidal interactions or the weakness of the primary bar. These findings suggest that slow bars may be more observed in galaxies with nuclear structures and highlight the often underappreciated role of galaxy interactions in bar evolution.

We have performed timing of a number of known slow pulsars with poorly known coordinates and parameters of their intrinsic rotation. We used data from the archive of round-the-clock monitoring observations on the third (stationary) beam pattern of the Large Phased Array radio telescope (LPA LPI) at a frequency of 111 MHz, which has an unsatisfactory connection of the local quartz time standards to the reference scale (UTC). To compensate for the resulting errors, we applied an algorithm previously developed by us, which uses Pulsar Timescale as an intermediate reference scale to compute corrections to the pulses Times of Arrival (TOAs) measured by the local clocks and to switch to UTC. Analyzing a ten-year observational data set we substantially refined the rotational and astrometric parameters of 12 pulsars. The spin frequencies $\nu$ and their first derivatives $\dot\nu$ were determined with accuracies of $10^{-10}$ Hz and $10^{-19}$ s$^{-2}$, respectively, which is 5-6 orders of magnitude better than the values quoted in the catalogue. The coordinates are determined with accuracies ranging from units to tens of arcseconds.

We present ground-based, multi-band light curves of the AGN Mrk~509, NGC\,4151, and NGC\,4593 obtained contemporaneously with \sw\, monitoring. We measure cross-correlation lags relative to \sw\, UVW2 (1928~Å) and test the standard prediction for disk reprocessing, which assumes a geometrically thin, optically thick accretion disk where continuum interband delays follow the relation \( \tau(\lambda) \propto \lambda^{4/3} \). For Mrk~509 the 273-d \sw\, campaign gives well-defined lags that increase with wavelength as $\tau(\lambda)\propto\lambda^{2.17\pm0.2}$, steeper than the thin-disk prediction, and the optical lags are a factor of $\sim5$ longer than expected for a simple disk-reprocessing model. This ``disk-size discrepancy'' as well as excess lags in the $u$ and $r$ bands (which include the Balmer continuum and H$\alpha$, respectively) suggest a mix of short lags from the disk and longer lags from nebular continuum originating in the broad-line region. The shorter \sw\, campaigns, 69~d on NGC\,4151 and 22~d on NGC\,4593, yield less well-defined, shorter lags $<2$~d. The NGC\,4593 lags are consistent with $\tau(\lambda) \propto \lambda^{4/3}$ but with uncertainties too large for a strong test. For NGC\,4151 the \sw\, lags match $\tau(\lambda) \propto \lambda^{4/3}$, with a small $U$-band excess, but the ground-based lags in the $r$, $i$, and $z$ bands are significantly shorter than the $B$ and $g$ lags, and also shorter than expected from the thin-disk prediction. The interpretation of this unusual lag spectrum is unclear. Overall these results indicate significant diversity in the $\tau-\lambda$ relation across the optical/UV/NIR, which differs from the more homogeneous behavior seen in the \sw\, bands.

We investigated colour gradients of photometrically selected post-starburst galaxies (PSBs) at $0.7 < z < 0.9$ in the COSMOS field as a function of central concentration of asymmetric features, $C_{A}$, in order to understand their origins. We measured the colour gradients for 33 PSBs, 332 quiescent galaxies (QGs), and 1136 star-forming gaaxies (SFGs) by using COSMOS $HST$/ACS $I_{F814W}$-band and COSMOS-DASH $HST$/WFC3 $H_{F160W}$-band data. We found that the colour gradient, $\Delta (I-H) = (I-H)_{in} - (I-H)_{out}$, decreases with increasing $C_{A}$ for all the three populations. Only PSBs with $\log{C_{A}} > 0.6$ show positive gradients, which suggests that their central asymmetric features are caused by disturbed distribution of relatively young stars near the centre. The colour gradients are also closely related with half-light radius rather than stellar mass for all the populations. The positive colour gradients and very small sizes of those PSBs with high $C_A$ suggest that a nuclear starburst caused by gas-rich major merger occurred in the recent past. On the other hand, similarly massive PSBs with $\log C_A < 0.6$ show the negative colour gradients, heavier dust extinction, and larger sizes, and their origins may be different from those PSBs with high $C_A$.

CORSIKA 8 represents a significant update in the simulation of particle showers, building on the well-established foundation of CORSIKA 7. It has been entirely rewritten as a modular and modern C++ framework, addressing the limitations of its predecessor to provide a flexible platform designed to satisfy current and novel use cases. This allows for application beyond pure air-shower scenarios such as cross-media particle cascades and an advanced calculation of the radio emission. A first official "physics-complete" version has already been released that supports the treatment of hadronic interactions with Sibyll 2.3d, QGSJet-II.04, and EPOS-LHC and the treatment of the electromagnetic cascade with PROPOSAL 7.6.2. In this presentation, we will discuss the design principles, current functionality, and validation efforts of CORSIKA 8, emphasizing its potential applications for future experiments.

Recent detections of optical pulsations from both a transitional and an accreting millisecond pulsar have revealed unexpectedly bright signals, suggesting that the presence of an accretion disk enhances the efficiency of optical emission, possibly via synchrotron radiation from accelerated particles. In this work, we present optical observations of the redback millisecond pulsar PSR J2339-0533, obtained with the SiFAP2 photometer mounted on the Telescopio Nazionale Galileo. Data accumulated during the campaign with the longest exposure time (12 hr) suggest that its $\sim$18 mag optical counterpart exhibits pulsations at the neutron star's spin frequency. This candidate signal was identified by folding the optical time series using the pulsar ephemeris derived from nearly simultaneous observations with the 64-m Murriyang (Parkes) radio telescope. The detection significance of the candidate optical signal identified in those data lies between 2.9 and 3.5 $\sigma$, depending on the statistical test employed. The pulsed signal has a duty cycle of $\approx 1/32$, and the de-reddened pulsed magnitude in the V band is $(26.0 \pm 0.6)$ mag. At a distance of 1.7 kpc, this corresponds to a conversion efficiency of $\sim 3 \times 10^{-6}$ of the pulsar's spin-down power into pulsed optical luminosity, comparable to values observed in young, isolated pulsars like the Crab, but 50-100 times lower than in disk-accreting millisecond pulsars. If confirmed, these findings suggest that optical pulsations arise independently of an accretion disk and support the notion that such disks boost the optical emission efficiency.

Large-scale solar eruptions are generally accepted to have coronal magnetic flux ropes as their core structures. Recent studies found that the solar eruptions could be initiated by a sequence of flux feeding processes, during with chromospheric fibrils rise and merge with the pre-existing coronal flux rope. Further theoretical analyses have demonstrated that the normal flux feeding, i.e. the axial magnetic flux within the fibril is in the same direction as that in the flux rope, results in the accumulation of the total axial flux within the flux rope, so as to initiate the eruption. If the directions of the axial flux in the fibril and the flux rope are opposite, it is termed inverse flux feeding, whose influence on coronal flux ropes, however, is still unclear. In this paper, we use a 2.5-dimensional magnetohydrodynamic model to simulate the evolution of coronal flux ropes associated with inverse flux feeding. It is found that inverse flux feeding is also efficient in causing solar eruptions: although the total signed axial magnetic flux of the rope decreases after inverse flux feeding, the total unsigned axial flux can accumulate; the eruption occurs if the unsigned axial flux of the rope reaches a critical value, which is almost the same as the threshold for normal flux feeding. The total axial currents within the rope are also similar during the onset of the eruptions caused by both normal and inverse flux feeding. Our simulation results suggest that it is the unsigned axial magnetic flux rather than the signed axial flux that regulates the onset of coronal flux rope eruptions.

Little Red Dots (LRDs) are compact sources at $z>5$ discovered through JWST spectroscopy. Their spectra exhibit broad Balmer emission lines ($\gtrsim1000\rm~km~s^{-1}$), alongside absorption features and a pronounced Balmer break -- evidence for a dense, neutral hydrogen medium with the $n=2$ state. When interpreted as arising from AGN broad-line regions, inferred black hole masses from local scaling relations exceed expectations given their stellar masses, challenging models of early black hole--galaxy co-evolution. However, radiative transfer effects in dense media may also impact the formation of hydrogen emission lines. We model three scattering processes shaping hydrogen line profiles: resonance scattering by hydrogen in the $n=2$ state, Raman scattering of UV radiation by ground-state hydrogen, and Thomson scattering by free electrons. Using 3D Monte Carlo radiative transfer simulations with multi-branching resonance transitions, we examine their imprint on line shapes and ratios. Resonance scattering produces strong deviations from Case B flux ratios, clear differences between H$\alpha$ and H$\beta$, and encodes gas kinematics in line profiles but cannot broaden H$\beta$ due to conversion to Pa$\alpha$. While Raman scattering can yield broad wings, scattering of UV continuum is disfavored given the absence of strong FWHM variations across transitions. Raman scattering of higher Lyman-series emission can produce H$\alpha$/H$\beta$ wing width ratios of $\gtrsim1.28$, agreeing with observations. Thomson scattering can reproduce the observed $\gtrsim1000~\rm km\, s^{-1}$ wings under plausible conditions, e.g., $T_{\rm e} \sim 10^4\rm \, K$ and $N_{\rm e}\sim10^{24}\rm~cm^{-2}$ -- and lead to black hole mass overestimates by factors $\gtrsim10$. Our results provide a framework for interpreting hydrogen lines in LRDs and similar systems.

Recently, the KM3NeT collaboration detected an astrophysical neutrino event, KM3-230213A, with an energy of approximately $220~\rm PeV$, providing unprecedented insights into the ultra-high-energy Universe. In this study, we introduce a novel likelihood framework designed to leverage this event to constrain the properties of super-heavy dark matter (SHDM) decay. Our approach systematically integrates multi-messenger constraints from galactic and extragalactic neutrino flux measurements by IceCube, the absence of comparable neutrino events at IceCube and Auger observatories, and the latest gamma-ray experiment upper limits. Our findings impose the most stringent constraints to date, placing a lower bound on the SHDM lifetime at $\gtrsim 5\cdot 10^{29}-10^{30} \rm s$. Importantly, we identify, for the first time, the significant potential of galactic neutrino flux measurements in advancing dark matter research. Future investigations targeting astrophysical neutrinos originating from the Galactic Center at energies above $10~\rm PeV$ will be crucial, not only for understanding the origin of the cosmic-ray knee but also for exploring the possible contributions of super-heavy dark matter to our Universe.

The simulation of extensive air showers is pivotal for advancing our understanding of high-energy cosmic ray interactions in Earth's atmosphere. The CORSIKA 8 framework is being developed as a modern, flexible, and efficient tool for simulating these interactions with a variety of high-energy hadronic models. We present the ongoing implementation and validation of Pythia 8/Angantyr within CORSIKA 8. Pythia 8, successfully used in collider physics, provides a detailed and well-tested treatment of hadronic interactions, while the Angantyr model extends its capabilities to describe heavy-ion collisions in a consistent manner. With the inclusion of Pythia 8, the CORSIKA 8 suite now enables further tuning possibilities, improving the exploration of hadronic interactions in air showers. In this contribution, we compare the capability of Pythia 8/Angantyr to reproduce fundamental observables of high-energy particle collisions $-$ inelastic cross-sections and multiplicities $-$ to that of several established high-energy interaction models in air shower simulations. We further compare the predictions for key air shower properties, including longitudinal shower development and muon content, for iron-induced shower.

The Solar Ultraviolet Imaging Telescope (SUIT) is an instrument onboard Aditya--L1, the first solar space observatory of the Indian Space Research Organization (ISRO), India, launched on September 2, 2023. SUIT is designed to image the Sun in the 200--400 nm wavelength band in eight narrowband and three broadband filters. SUIT's science goals start with observing the solar atmosphere and large-scale continuum variations, the physics of solar flares in the NUV region, and many more. The paper elucidates the functioning of the instrument, software packages developed for easier calibration, analysis, and feedback, calibration routines, and the regular maintenance activity of SUIT during the first year of its operation. The paper also presents the various operations undergone by, numerous program sequences orchestrated to achieve the science requirements, and highlights some remarkable observations made during the first year of observations with SUIT.

3I/ATLAS, also known as C/2025 N$_1$ (ATLAS), is the third interstellar object (ISO) discovered in July 2025. ISOs are particularly interesting because characterizing their physical properties helps us understand and test our knowledge of Solar System formation. Several quick response observations of 3I/ATLAS were performed during the first few days after the discovery, and various results, such as reflectance spectra, have been reported. We performed simultaneous visible spectrophotometry of 3I/ATLAS from data taken using the TriColor CMOS Camera and Spectrograph (TriCCS) on the Seimei 3.8 m telescope. The Seimei/TriCCS observations of 3I/ALTAS were obtained in the $g$, $r$, $i$, and $z$ bands in the Pan-STARRS system on UTC July 15, 2025. Our lightcurves show no significant variations during the 2.3 h observation, which is in good agreement with previous studies. Visible color indices of 3I/ATLAS, $g-r=0.603\pm0.031$, $r-i=0.210\pm0.031$, $i-z=0.117\pm0.046$, and $r-z=0.327\pm0.035$ suggest it has a red surface similar to, or slightly redder than, that of D-type asteroids. Continuous observations of 3I/ATLAS before and after its perihelion passage in October 2025 are desired to investigate its physical properties.

We present a novel method of combining kinematic models obtained at multiple spatial resolution levels in a physically self-consistent manner. The MHONGOOSE survey has mapped atomic hydrogen emission in $30$ nearby dwarf and spiral galaxies. Each galaxy is imaged at multiple resolution levels with unprecedented dynamic range in spatial resolution (from $\sim 10''$ to $ 90''$) and HI sensitivity, with the latter varying by almost a factor of $30$ across all resolution scales. We use radial weighting functions to combine kinematic models from all resolution levels. The weights are derived from the residuals of model fits to a set of simulated galaxy observations with known rotation curves and geometries. We obtain combined (weighted and smoothed) inclination and position angle profiles for each galaxy. These suppress the sharp, often unphysical radial fluctuations arising in single-resolution profiles. We then fit the rotation speed and velocity dispersion profiles at each resolution level with the geometric profiles fixed to the combined profiles, finally combining these using the same weighting and smoothing approach. The combined rotation curves utilise all of the available information and have smaller typical errors compared to those obtained using a single resolution level, particularly near the centres and outer edges of models. This initial demonstration is promising; there is scope to further refine the process to use such information-rich observations to their full potential.

In the following paper I have compared some typical mass-radius relations for main sequence stars by studying their level of agreement with DEBCat [this https URL], which is a recent catalogue by J. Southworth. Models chosen for testing were originally developed using older, smaller datasets than DEBCat. Each model follows a two-piece function structure, where each branch is a monomial power-law. This approach is motivated by theoretical considerations suggesting that low-mass and high-mass main sequence stars exhibit distinct behaviors in energy production and energy transport. Best level of agreement is found for Zamorano's model [this https URL]. Also a new empirical relation is proposed by fitting a two-piece monomial power-law to DEBCat main sequence stars.

We present a strictly line-by-line differential analysis of a moderately $r$-process-enhanced star ($r$-I: HD~107752) with respect to a strongly $r$-process-enhanced star ($r$-II: CS~31082-0001) to investigate the possible common origin of their heavy-element nucleosynthesis with high-precision abundances. This study employs ESO data archive high-resolution and high signal-to-noise spectra taken with the UVES (VLT) spectrograph. Considering only the lines in common in both spectra, we estimate differential abundances of 16 light/Fe-peak elements and 15 neutron-capture elements. Abundances of O, Al, Pr, Gd, Dy, Ho, Er, and detection of Tm in HD~107752 are presented for the first time. We found three distinct features in the differential-abundance pattern. Nearly equal abundances of light elements up to Zn are present for both the stars, indicating a common origin for these elements; in addition to no noticable odd-even differential pattern. In the case of neutron-capture elements, the $r$-I star exhibits mildly depleted light $r$-process elements and more depleted heavier $r$-process elements relative to $r$-II star. We also show that among $r$-I and $r$-II stars, the ratio of lighter-to-heavier $r$-process elements (e.g. [(Sr,Y,Zr)/Eu]) exhibits a decreasing trend with respect to the overall $r$-process enhancement, forming a continuous sequence from $r$-I and $r$-II stars. Finally, we discuss the necessity of multiple sites for the formation of $r$-I stars.

We use cosmological hydrodynamic simulations (IllustrisTNG and SIMBA) to explore the redshift, luminosity, and black hole mass dependence of the quasar halo occupation distribution (HOD). In both simulations, we find that the quasar activity is quenched at a characteristic halo mass ($\sim 10^{13} M_{\odot}$) scale affecting the nature of its occupation distribution function. We note that the quenching is more pronounced at low redshifts for quasars selected through a luminosity threshold. We show that a very significant bias ({\bf a factor of $\sim 10-50$ in the central occupation and $\sim 10-70\%$ in the satellite occupation fraction}) is introduced in the reconstruction of quasar host halo mass distributions from the observed two-point-correlation function, if the HOD modeling does not account for the quenching effect in the central occupation function. While there is strong suppression of the occupation fraction of central quasars, the satellite occupation still follows a power-law like behavior. Our results show that the global satellite fraction of quasars increases monotonically from high to low redshifts, with $20-40 \%$ of the quasars being satellite at intermediate redshifts, consistent with previous clustering based estimates. In addition, our study reveals that while the occupation function of quasars depends on redshift, luminosity, and feedback modes, there is hardly any evolution in the supermassive black hole (SMBH; mass-selected sample) occupation. The SMBH HOD over the entire parameter space is well-modeled by a power-law and a step function similar to what has been found for galaxies and low-luminosity active galactic nuclei.

SST-1M is a prototype single mirror Small Sized Cherenkov Telescope designed for very high energy (VHE) gamma-ray astronomy. With a 4 meter primary mirror and a 5.6 meter focal length, it provides a wide 9 degree optical field of view, optimized for detecting VHE gamma-rays from 1 TeV to several hundred TeV. Its focal plane is equipped with DigiCam, a fully digital trigger and readout camera made of 1296 silicon photomultiplier (SiPM) pixels. The use of SiPM sensors enables observation under high night sky background (NSB) conditions, significantly enhancing the instrument's duty cycle and allowing observations under moonlight. Currently, two SST-1M telescopes are deployed at the Ond\v rejov Observatory in the Czech Republic, operating in stereo, at 510 m altitude, to observe astrophysical sources. This contribution presents the SiPM calibration procedure and performance validation of the instrument, based on updated results from Crab Nebula observations.

We present the results of testing an iXonUltra 888 EMCCDcamera to determine the operating parameters for short-exposure photometry of stars. As a result of the testing, those camera modes were selected in which the temporal instability of the electron multiplication charge does not significantly affect the light curves. In addition, the photometry of the eclipsing variable star ZTFJ 0038+2030, obtained with the Zeiss-1000 telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences, is presented. We have shown the advantages and disadvantages of 1-s exposures for studying variable stars.

A major challenge in understanding the initiation and evolution of coronal mass ejections (CMEs) is measuring the magnetic field of the magnetic flux ropes (MFRs) that drive CMEs. Recent developments in radio imaging spectroscopy have paved the way for diagnosing the CMEs' magnetic field using gyrosynchrotron radiation. We present magnetic field measurements of a CME associated with an X5-class flare by combining radio imaging spectroscopy data in microwaves (1--18 GHz) and meter-wave (20--88 MHz), obtained by the Owens Valley Radio Observatory's Expanded Owens Valley Solar Array (EOVSA) and Long Wavelength Array (OVRO-LWA), respectively. EOVSA observations reveal that the microwave source, observed in the low corona during the initiation phase of the eruption, outlines the bottom of the rising MFR-hosting CME bubble seen in extreme ultraviolet and expands as the bubble evolves. As the MFR erupts into the middle corona and appears as a white light CME, its meter-wave counterpart, observed by OVRO-LWA, displays a similar morphology. For the first time, using gyrosynchrotron spectral diagnostics, we obtain magnetic field measurements of the erupting MFR in both the low and middle corona, corresponding to coronal heights of 1.02 and 2.83 $R_{\odot}$. The magnetic field strength is found to be around 300 G at 1.02 $R_{\odot}$ during the CME initiation, and about 0.6 G near the leading edge of the CME when it propagates to 2.83 $R_{\odot}$. These results provide critical new insights into the magnetic structure of the CME and its evolution during the early stages of its eruption.

The detection by the Carpet-3 Group of a 300 TeV photon, observed 4536 seconds after the prompt emission of the historic gamma-ray burst GRB 221009A, provides unprecedented opportunities to test Lorentz invariance violation (LV) at energy scales approaching the Planck regime. By analyzing the temporal and spatial properties of this ultra-high-energy photon in conjunction with lower-energy photons from other bursts and the same burst, we demonstrate consistency with subluminal LV scenarios characterized by an energy scale \( E_{\rm LV} \sim 3 \times 10^{17} \, \rm{GeV} \). This work bridges multi-year LV studies using GeV-TeV photons and establishes GRB 221009A as a pivotal laboratory for quantum spacetime phenomenology.

Gaia has recently revealed a population of over 20 compact objects in wide astrometric binaries, while LIGO-Virgo-KAGRA (LVK) have observed around 100 compact object binaries as gravitational-wave (GW) mergers. Despite belonging to different systems, the compact objects discovered by both Gaia and the LVK follow a multimodal mass distribution, with a global maximum at neutron star (NS) masses ($\sim 1$-$2\,M_\odot$) and a secondary local maximum at black hole (BH) masses $\sim10\,M_\odot$. However, the relative dearth of objects, or ``mass gap," between these modes is more pronounced among the wide binaries observed by Gaia compared to the GW population, with $9^{+10}_{-6}\%$ of GW component masses falling between $2.5$--$5\,M_\odot$ compared to $\lesssim5\%$ of Gaia compact objects. We explore whether this discrepancy can be explained by the natal kicks received by low-mass BHs. GW progenitor binaries may be more likely to survive natal kicks, because the newborn BH has a more massive companion and/or is in a tighter binary than Gaia progenitor binaries. We compare the survival probabilities of Gaia and GW progenitor binaries as a function of natal kick strength and pre-supernova binary parameters, and map out the parameter space and kick strength required to disrupt the progenitor binaries leading to low-mass BHs in Gaia systems more frequently than those in GW systems.

Context. Gamma-ray bursts (GRBs) have traditionally been classified by duration into long (LGRBs) and short (SGRBs), with the former believed to originate from massive star collapses and the latter from compact binary mergers. However, events such as the SGRB 200826A (coming from a collapsar) and the LGRBs 211211A and 230307A (associated with a merger) suggest that duration-based classification could be sometimes misleading. Recently, the minimum variability timescale (MVT) has emerged as a key metric for classifying GRBs. Aims. We calculate the MVT, defined as the full width at half maximum (FWHM) of the narrowest pulse in the light curve, using an independent dataset from Fermi/GBM and we compare our results with other MVT definitions. We update the MVT-T90 plane and analyse peculiar events like long-duration merger candidates 211211A, 230307A, and other short GRBs with extended emission (SEE-GRBs). We also examine extragalactic magnetar giant flares (MGFs) and explore possible new correlations with peak energy. Methods. We used the MEPSA algorithm to identify the shortest pulse in each GRB light curve and measure its FWHM. We calculated the MVT for around 3700 GRBs, 177 of which with spectroscopically known redshift. Results. SEE-GRBs and SGRBs share similar MVTs (from few tens to a few hundreds of ms), indicating a common progenitor, while extragalactic MGFs exhibit even shorter values (from few ms to few tens of ms). Our MVT estimation method consistently yields higher values than another existing technique, the latter aligning with the pulse rise time. For LGRBs, we confirmed the correlations of MVT with peak luminosity and Lorentz factor. Conclusions. We confirmed that, although MVT alone cannot determine the GRB progenitor, it is a valuable tool when combined with other indicators, helping to flag long-duration mergers and distinguish MGFs from typical SGRBs.

This paper constructs a theoretical framework for calculating the distribution of masses for secondary bodies forming via gravitational instability in the outer regions of circumstellar disks. We show that several alternate ways to specify the mass scale of forming objects converge to the same result under the constraint that the parental disks are marginally stable with stability parameter $Q=1$. Next we show that the well-known constraint that the formation of secondary bodies requires rapid cooling is equivalent to that of opacity limited fragmentation. These results are then used to derive a mass function for secondary objects forming through disk instablity. The resulting distribution is relatively narrow, with log-normal-like shape, a characteristic mass scale of order $M_{\scriptstyle \rm P}\sim10M_{\scriptstyle \rm Jup}$ and an approximate range of $4-80M_{\scriptstyle \rm Jup}$. Current estimates for the occurrence rate suggest that these objects are outnumbered by both stars and planets formed via core accretion.

Primarily motivated by the Hubble tension, we analyze the varying electron mass model and axionlike early dark energy model (EDE) using baryon acoustic oscillation data from DESI DR2 data and including the recent results from ACT DR6. Our analysis indicates that $m_{e} / m_{e0} = 1.0081 \pm 0.0046 $ and the energy fraction of EDE is constrained as $f_\mathrm{EDE} < 0.016$. Since those cosmological models fit with different spectral index $n_s$, we show the posterior of those models on the ($n_s-r$) plane and point out that, for example, Starobinsky inflation works for varying electron mass model while the standard supersymmetric hybrid inflation is preferred in the EDE model.

We present a comparative spectral analysis to explore the ability of a cooler Sun model to accurately capture the spectral line shape changes caused by Sunspots. In the search for small Earth-like planets, the effects of stellar surface activity can overwhelm the $\sim$10 cm/s planetary RV signal. This necessitates the development of new stellar modeling methods and a greater understanding of the impact of surface activity on stellar spectra. Some attempts to model out noise from Sunspot activity, in particular, have used a sum of a stellar model with a model of a cooler, but otherwise identical star. From our analysis, we find that a cooler effective temperature alone cannot capture the numerous spectral line shape variations seen in a Sunspot observation. The cooler temperature of a Sunspot not only deepens the cores of atomic lines, it also increases and strengthens molecular lines that are not fully represented in our line list. Furthermore, our LTE models and a comparison cool star also fail at capturing line strengthening, broadening, blending, and splitting induced by the magnetic field in the Sunspot.

The IceCube Neutrino Observatory at the South Pole detects neutrinos of astrophysical origin via their interactions with ice. The main array is optimized for the detection of neutrinos with energies above 1 TeV. A much smaller infill array, known as IceCube DeepCore, extends the sensitivity down to a few GeV. Neutrinos observed in both parts of the detector are used for astrophysical-source searches with multiple messengers. We present two analyses that follow up archival gravitational wave (GW) events from runs O1 through O3 of LIGO/Virgo/KAGRA. The first analysis uses two neutrino datasets: one with high-energy tracks and another consisting of low-energy tracks and cascades. These two neutrino datasets were previously used independently to follow-up GW events. In the analysis presented here, a combined likelihood search is performed using both datasets to search for neutrinos coincident with the GW events across a wide energy range, from a few GeV to several PeV. The second analysis, for the first time, uses a neutrino-induced cascade sample with events of energy above ~1 TeV for searches of coincident neutrino-GW emission. We present results from both analyses and discuss prospects for conducting these analyses in real time.

We present a measurement of the non-Gaussian four-point correlation function (4PCF) from the DESI DR1 Luminous Red Galaxy (LRG) sample. For the gravitationally induced parity-even 4PCF, we detect a signal with a significance of 14.7$\sigma$ using our fiducial setup. We assess the robustness of this detection through a series of validation tests, including auto- and cross-correlation analyses, sky partitioning across multiple patch combinations, and variations in radial scale cuts. Due to the low completeness of the sample, we find that differences in fiber assignment implementation schemes can significantly impact estimation of the covariance and introduce biases in the data vector. After correcting for these effects, all tests yield consistent results. This is one of the first measurements of the connected 4PCF on the DESI LRG sample: the good agreement between the simulation and the data implies that the amplitude of the density fluctuation inferred from the connected 4PCF is consistent with the Planck $\Lambda$CDM cosmology. The methodology and diagnostic framework established in this work provide a foundation for interpreting parity-odd 4PCF.

In low luminosity active galactic nuclei like M87$^*$ and Sgr A$^*$, the accretion flow in the vicinity of the black hole is in the collisionless regime, meaning that the collisional mean free path of charged particles is much larger than the dynamic length scales. To properly model the particle energization and emission from the collisionless accretion flow, a promising approach is to employ the global general relativistic particle-in-cell simulations -- a newly developed, fully kinetic, first-principles method. However, it has been challenging to set up an initial condition that involves collisionless gas with finite angular momentum. We present, for the first time, a class of analytic kinetic equilibria of collisionless tori around a Kerr black hole. We have successfully implemented the collisionless tori in our GPU-based GRPIC code framework Aperture, and found them to be stable for hundreds to thousands of dynamical times in 2D axisymmetric simulations when there is no initial seed magnetic field. These kinetic equilibria serve as ideal starting points for future studies of the physics of collisionless accretion and jet launching.

Modern radio interferometers are designed with increasingly sprawling geographical footprints, offering enhanced sensitivity and resolution. However, managing such extensive facilities presents operational challenges that can potentially impede or delay scientific progress. One solution to such obstacles is the `swarm telescope' concept which enables collaborative use of individual telescope systems, overseen by separate institutions, to create a more powerful and manageable facility. We present the design, construction, and commissioning of the Long Wavelength Array -- North Arm (LWA-NA) station, a prototype 64-element LWA Swarm telescope. LWA-NA is a cost-efficient, rapidly deployable platform for radio astronomy, and serves as a pathfinder for the larger LWA Swarm project.

Line intensity mapping (LIM) is an emerging technique for probing the large scale structure (LSS) in the post-reionisation era. This captures the integrated flux of a particular spectral line emission from multiple sources within a patch of the sky without resolving them. Mapping different galaxy line emissions, such as the HI $21$-cm and CO rotational lines via LIM, can reveal complementary information about the bias with which the line emitters trace the underlying matter distribution and how different astrophysical phenomena affect the clustering pattern of these signals. The stage where the structures in the cosmic web merge to form a single connected structure is known as the percolation transition. Using mock HI $21$-cm and CO($1-0$) LIM signals in the post-reionisation universe, we explore the connectivity of structures through percolation analysis and compare it with that of the underlying galaxy distribution. We probe the relative contributions of voids, filaments, and sheets to the galaxy density and line intensity maps using a morphological measure known as the local dimension. The CO($1-0$) map exhibits an increased filamentary behaviour and larger contribution from sheets than the $21$-cm map. We attempt to explain such an emission of the CO($1-0$) line from biased environments. The upcoming SKA-Mid will produce tomographic intensity maps of the $21$-cm signal at $z \lesssim 3$ in Band-1. CO maps can be produced at these redshifts in phase 2 of SKA-Mid, where the frequency coverage is expected to increase up to $\sim 50$ GHz. We present forecasts for the recovery of the local dimensions of these intensity maps contaminated by instrumental noise, considering SKA-Mid observations.

The origin of the high-alpha component of the Galactic bulge remains debated, unlike the bar-driven origin of the low-alpha bulge. We examine the metallicity-dependent dynamical properties of high-[Mg/Fe] stars in the bar region, using samples of low- and high-[Mg/Fe] stars from APOGEE DR17, complemented by the PIGS catalogue of [Fe/H] $ < -1 $ stars. The mean Galactocentric rotational velocity $ \overline V_\phi(R) $ is nearly cylindrical for both low- and high-[Mg/Fe] stars across the bulge and outer bar. $\overline V_\phi(R)$ of high-[Mg/Fe] stars with [Fe/H] $ \ge -0.6 $ is similar within errors to low-[Mg/Fe] stars in the bulge, and $ 10-20\% $ lower in the outer bar. The mean radial velocity field of these stars exhibits a quadrupole pattern similar to low-[Mg/Fe] stars. Orbit integrations in realistic barred Galactic potentials show that these model-independent properties correspond to a peanut bulge in the orbital density distributions for high-[Mg/Fe] stars with [Fe/H] $ \ge -0.6 $, transitioning toward a more spheroidal structure at lower metallicities. Additionally, $ \overline V_\phi$ ([Fe/H]) increases steeply as metallicity rises from about [Fe/H] $ \sim -1.3 $, resembling the spin-up observed at larger Galactic radii. This is accompanied by a transition in the dominant orbit families, from co- and counter-rotating cloud A and $ \rm x_4 $ orbits at low metallicities to co-rotating bar-supporting $ \rm x_1 $ family tree, box, and cloud A orbits at solar metallicity. Our results strengthen the case that the bulk of the high-[Mg/Fe] component in the bar region evolved from an alpha-enhanced disc, while metal-poor stars with [Fe/H] $ < -1 $ trace a more turbulent origin.

This paper presents a follow-up to previous work on correcting PSF-induced Doppler artifacts in observations by the SPICE spectrograph on Solar Orbiter. In a previous paper, we demonstrated correction of these artifacts in the $y-\lambda$ plane with PSF Regularization, treating the forward problem with a method based on large sparse matrix inversion. It has since been found that similar apparent artifacts are also present in the $x-\lambda$ direction, i.e., across adjacent slit positions. This is difficult (although not impossible) to correct with the previous matrix inversion method due to the time variation between slit positions. We have therefore devised a new method which addresses both $x-\lambda$ and $y-\lambda$ artifacts simultaneously by applying wavelength dependent shifts at each $x-y$ plane of the spectral cube. This paper demonstrates the SPICE data issue, describes the new method, and shows a comparison with the previous one. We explore the time variation of the correction parameters for the SPICE data and show a clear orbit dependence. The results of the method are significantly higher quality derived Doppler signals, which we estimate at less than $\sim$ 5 km/s uncertainty for brighter lines in the absence of other systematics. Furthermore, we show the new SPICE polar observation results as a demonstration. The correction codes are written in Python, publicly available on GitHub, and can be directly applied to SPICE level 2 datasets.

Here we report the first measurement of the parity-violating (PV) 4-Point Correlation Function (4PCF) of the Dark Energy Spectroscopic Instrument's Year 1 Luminous Red Galaxy (DESI Y1 LRG) sample, motivated by the potential detection of the PV 4PCF in the Sloan Digital Sky Survey Baryon Oscillation Spectroscopic Survey (SDSS BOSS) galaxies. In our auto-correlation ("auto") analysis, we find a statistically significant excess of the PV signal compared to mocks without any PV, at 4-10$\sigma$ depending on details of the analysis. This could arise either from genuine PV or from an underestimation of the variance in the mocks; it is unlikely to arise, at the signal level, from a systematic. We then cross-correlate ("cross") the putative PV signal between different, independent patches of sky, and there find no detection of parity violation. The two measurements are in significant tension: while the cross has somewhat larger error bars than the auto, this is not sufficient to explain the discrepancy. We thus present the current work as an intriguing addition to the PV work on BOSS and as motivation for exploring further the relationship between the auto and cross PV 4PCF analyses.

We study first order phase transitions that occur when the temperature of the system increases and we identify the conditions that lead to super-heating, a phase where the system can heat up arbitrarily. First order phase transitions with super-heating behave as inverse transitions. We quantify these claims by studying a prototypical example of a dark sector with a large number of interacting light bosons at finite temperature. Depending upon thermalisation, a super-heated phase transition in cosmology is often associated with another transition when the system is eventually cooling down, enriching the spectrum of gravitational waves from bubble collisions.

Neutrino Direct Simulation Monte Carlo approach ($\nu$DSMC) is a method of solving the neutrino Boltzmann equation in the Early Universe, proposed to study the evolution of neutrinos under various cosmological setups. We formulate a complete $\nu$DSMC solver, incorporating the effects of the electron mass, neutrino oscillations, and quantum corrections to the thermodynamics of the electromagnetic plasma. We then apply it for performing precise calculations of neutrino decoupling in the standard cosmological scenario. We obtain the value $N_{\text{eff}} = 3.0439\pm 0.0006$, in agreement with the state-of-the-art calculations.

We have introduced a new Fourier-expansion technique for computing gravitational-wave emission from non-spinning binaries in the post-Newtonian framework. Using this approach, we derived the full set of 3PN dynamical quantities and gravitational-wave Fourier modes and have released the corresponding numerical code as open source. Furthermore, applying the method to the tail contribution of the energy flux, we found that it can be resummed into an exceptionally compact expression. These advances pave the way for more convenient and accurate frequency-domain waveform modeling in the future.

We test the dark photon as a portal connecting to the dark sector in the case of Dirac fermion and complex scalar dark matter with masses up to 1 TeV. Both the dark photon and the $Z$ boson contribute to the dark matter annihilation and dark matter--nucleon scattering processes. We derive the lower limits on the dark parameters from thermal relic density. The corresponding spin-independent dark matter--proton cross sections are compared with the upper bounds set by direct detection. We explore the allowed regions of the dark parameter space that are consistent with these constraints.

We consider the quantum creation of a universe with flat spatial sections and the topology of a 3-torus, taking into account the effect of Casimir energy. We show that the corresponding instantons are singular. Since these instantons describe universes originating in a state of infinite energy, we argue that they cannot be interpreted as quantum creation from `nothing'. If quantum corrections to the energy-momentum tensor are neglected, the spacetime of the toroidal universe reduces to de Sitter space with appropriate periodic identifications. Contrary to previous claims in the literature, this spacetime is geodesically incomplete. We argue that this spacetime describes a classical universe originating at a singularity, and not a quantum origin. We conclude that the quantum creation of a toroidal universe from nothing cannot be described in the context of semiclassical quantum gravity -- it is either impossible, or it depends essentially on Planck-scale physics. We therefore see no reasonable way to compare the probability of creation of a toroidal universe, if it is possible at all, with that of a spherical universe.

GW230529_181500 represented the first gravitational-wave detection with one of the component objects' mass inferred to lie in the previously hypothesized mass gap between the heaviest neutron stars and the lightest observed black holes. Given the expected maximum mass values for neutron stars, this object was identified as a black hole, and, with the secondary component being a neutron star, the detection was classified as a neutron star-black hole merger. However, due to the low signal-to-noise ratio and the known waveform degeneracy between the spin and mass ratio in the employed gravitational-wave models, GW230529_181500 could also be interpreted as a merger of two heavy ($\gtrsim 2 \mathrm{M}_\odot$) neutron stars with high spins. We investigate the distinguishability of these scenarios by performing parameter estimation on simulated signals obtained from numerical-relativity waveforms for both neutron star-black hole and binary neutron star systems, with parameters consistent with GW230529_181500, and comparing them to the analysis of the real event data. We find that GW230529_181500 is more likely to have originated from a neutron star-black hole merger, though the possibility of a binary neutron star origin can not be ruled out. Moreover, we use the simulation data to estimate the signatures of potential electromagnetic counterparts emitted by the systems. We find them to be too dim to be located by current wide-field surveys if only the dynamical ejecta is considered, and detectable by the Vera C. Rubin Observatory during the first two days after merger if one accounts for additional disk wind ejecta.

The $F(R)$ gravity models of inflation are revisited in light of the recent observations of cosmic microwave background radiation by Atacama Cosmology Telescope (ACT) and DESI Collaboration. A detailed study of the evolution equations in the Jordan frame is given and a new description of the slow-roll approximation in the $F(R)$-gravity-based models of inflation is proposed. It is found that all those models of inflation are significantly constrained by demanding a higher (than the Planck Telescope value) cosmological tilt $n_s$ of scalar perturbations and a positive running index $\alpha_s$ favored by ACT. It is not difficult to meet the ACT constraints on the scalar tilt $n_s$ by modifying the existing models of inflation, but simultaneously demanding a positive running $\alpha_s$ would rule out many of them. Using the proposed slow-roll approximation in the Jordan frame, we provide a new modification of the Starobinsky inflation model in the framework of $F(R)$ gravity, which satisfies all ACT constraints.

The Stewart-Tolman effect posits that accelerating conductors exhibit both charge separation and rest-frame electric fields (``inertia of charge''), while the Ehrenfest-Tolman effect states that acceleration induces temperature gradients (``inertia of heat''). We study the interplay of these effects in thermodynamic equilibrium. Specifically, we derive from first principles a partial differential equation governing the electrothermal stratification of a fully ionized plasma in equilibrium under irrotational relativistic accelerations in curved spacetime. We then solve it in two settings: a plasma enclosed in a uniformly accelerated box, and a plasma shell suspended above a black hole horizon. The resulting electric fields are found not to depend on the electric conductivity of the medium.