Papers for Monday, Sep 15 2025

We present a sub-threshold search for gravitational-wave inspirals from binary neutron stars using data from the first part of the fourth observing run of the LIGO-Virgo-KAGRA Collaboration. To enhance sensitivity to this targeted population, we incorporate a redshift-corrected population model based on radio observations of Galactic double neutron star systems. The search identifies a significant trigger with a false-alarm rate of about one per 50 years and a network signal-to-noise ratio of 9.7, which was first reported by the LVK in low-latency processing as S231109ci and subsequently in the GWTC-4.0 catalog as GW231109_235456, a sub-threshold candidate. Accounting for a trials factor of five from the four LVK searches in GWTC-4.0 and this new search, the false-alarm rate of the reported candidate is approximately one per 10 years. If this event is of astrophysical origin, the inferred source properties indicate component masses of 1.40 to 2.24 solar masses for the primary and 0.97 to 1.49 solar masses for the secondary, yielding a total mass of 2.95 (+0.38, -0.07) solar masses. The event was localized to a region of 450 square degrees (90 percent probability) at a luminosity distance of 165 (+70, -69) megaparsecs.

Ultra-hot Jupiters exhibit day-to-night temperature contrasts upwards of 1000 K due to competing effects of strong winds, short radiative timescales, magnetic drag, and H2 dissociation/recombination. Spectroscopic phase curves provide critical insights into these processes by mapping temperature distributions and constraining the planet's energy budget across different pressure levels. Here, we present the first NIRISS/SOSS phase curve of an ultra-hot Jupiter, WASP-121 b. The instrument's bandpass [0.6 - 2.85 micron] captures an estimated 50-83% of the planet's bolometric flux, depending on orbital phase, allowing for unprecedented constraints on the planet's global energy budget; previous measurements with HST/WFC3 and JWST/NIRSpec/G395H captured roughly 20% of the planetary flux. Accounting for the unobserved regions of the spectrum, we estimate effective day and nightside temperatures of T_day = 2717 +/- 17 K and T_night = 1562 +/- 19 K corresponding to a Bond albedo of A_B = 0.277 +/- 0.016 and a heat recirculation efficiency of epsilon = 0.246 +/- 0.014. Matching the phase-dependent effective temperature with energy balance models yields a similar Bond albedo of 0.3 and a mixed layer pressure of 1 bar consistent with photospheric pressures, but unexpectedly slow winds of 0.2 km/s, indicative of inefficient heat redistribution. The shorter optical wavelengths of the NIRISS/SOSS Order 2 yield a geometric albedo of A_g = 0.093 +/- 0.029 (3 sigma upper limit of 0.175), reinforcing the unexplained trend of hot Jupiters exhibiting larger Bond albedos than geometric albedos. We also detect near-zero phase curve offsets for wavelengths above 1.5 micron, consistent with inefficient heat transport, while shorter wavelengths potentially sensitive to reflected light show eastward offsets.

We present the discovery of two low-mass, high-redshift, quiescent galaxies, GS-z5-Q1 and COS-z5-Q1, using JWST NIRSpec spectroscopy alongside NIRCam and MIRI photometry. Observed at a redshift of z=5.39 and z=5.11 respectively, and with stellar masses of $\rm 10^{9.6}M_\odot$ and $\rm 10^{9.5}M_\odot$, GS-z5-Q1 and COS-z5-Q1 are two of the most distant quiescent galaxies spectroscopically confirmed to-date, and are by far the least massive ($\sim10\times$ lower mass). Full spectrophotometric modelling reveals that COS-z5-Q1 appears to have quenched more than 300Myr prior to observation ($z\sim 7$) and has a formation redshift of around z$\sim$11, whilst GS-z5-Q1 formed and quenched in a single burst around 150Myr prior to observation ($z\sim6$). GS-z5-Q1 is found to lie near the centre of a known high-z overdensity in GOODS-S, as would be expected by galaxy formation models, while COS-z5-Q1 lies towards the outskirts of an overdense region. This highlights the role that environment could play in accelerating galaxy evolutionary processes and could possibly be linked to the galaxies' quiescent nature. By modelling their stellar populations, we show that these types of low-mass quiescent galaxies could potentially be descendants of the higher-z "mini-quenched" galaxies. The discovery of these two low-mass $z>5$ quiescent galaxies illuminates a previously undiscovered galaxy population and motivates dedicated follow-up surveys to investigate the overall population.

We seek to quantify the fidelity with which modern population syntheses reproduce observations in view of their use as predictive tools. We compared synthetic populations from the Generation 3 Bern Model of Planet Formation and Evolution (core accretion, solar-type host stars) and the HARPS/Coralie radial velocity sample. We biased the synthetic planet population according to the completeness of the observed data and performed quantitative statistical comparisons and systematically identified agreements and differences. Our nominal population reproduces many of the main features of the HARPS planets: two main groups of planets (close-in sub-Neptunes and distant giants), a bimodal mass function with a less populated `desert', an observed mean multiplicity of about 1.6, and several key correlations. The remaining discrepancies point to areas that are not fully captured in the model. For instance, we find that the synthetic population has 1) in absolute terms too many planets by ~70%, 2) a `desert' that is too deep by ~60%, 3) a relative excess of giant planets by ~40%, 4) planet eccentricities that are on average too low by a factor of about two (median of 0.07 versus 0.15), and 5) a metallicity effect that is too weak. Finally, the synthetic planets are overall too close to the star compared to the HARPS sample. The differences allowed us to find model parameters that better reproduce the observed planet masses, for which we computed additional synthetic populations. We find that physical processes appear to be missing and that planets may originate on wider orbits than our model predicts. Mechanisms leading to higher eccentricities and slower disc-limited gas accretion also seem necessary. We advocate that theoretical models should make a quantitative comparison between the many current and future large surveys to better understand the origins of planetary systems. (Abridged.)

[Shortened for arXiv] We conduct a systematic search for $\log(M_\ast/M_\odot) \geq 9.5$ quiescent galaxies at $z > 3$ in six extragalactic deep fields observed with NIRCam, with the goal of extracting their physical and statistical features in a uniform and self-consistent manner. We exploit the ASTRODEEP-JWST photometric catalogs to single out robust candidates, including sources quenched only a few tens of Myr before the observation. We apply a SED-fitting procedure which explores three functional forms of star formation history and the $\chi^2$ probabilities of the solutions, with additional checks to minimise the contamination from interlopers, tuning our selection criteria against available spectroscopic data from the DAWN archive and simulated catalogs. We select 633 candidates, which we rank by a reliability parameter based on the probabilities of the quiescent and alternative star-forming solutions, with 291 candidates tagged as "gold". According to the best-fit models, 79\% of the massive ($\log(M_\ast/M_\odot) \geq 10.5$) quiescent galaxies at $3 < z < 5$ stopped forming stars at least 150 Myr before the time of observation, while 89\% of low-mass sources have been quenched for less than 150 Myr. The abundance of low-mass old quiescent systems does not increase significantly with time from $z = 5$ to 3: low-mass objects seem to be experiencing a short episode of quenching followed by rejuvenation (``breathing''), consistent with a downsizing scenario of galaxy formation. We also find an abrupt drop in the density of massive quiescent candidates at $z > 5$. We derive estimates for the number density of early passive galaxies up to $z = 10$ and compare them against various models: tensions with data remain in the modeling of the observed bimodality of time passed since quenching as a function of mass.

The remnants of galaxy mergers may host multiple off-nuclear massive black holes (MBHs), some of which may wander indefinitely within the host galaxy halos. Tracing the population of offset MBHs is essential for understanding how the distribution of MBHs in the Universe evolves through galaxy mergers, the efficiency of binary MBH formation, and the rates at which MBHs are seeded in low-mass satellite galaxies. Offset MBHs can be observationally traced if they are accreting and detectable as spatially offset active galactic nuclei (AGN). In this work, we build the largest uniform sample of spatially offset AGN candidates (328) by matching sources from the Very Large Array Sky Survey (VLASS) to galaxies in the Sloan Digital Sky Survey (SDSS). Based on the radio source surface density, 29+/-3% are unrelated chance projections. The offset AGN occupation fraction is positively correlated with host galaxy stellar mass, consistent with predictions that most offset MBHs will reside in massive halos. However, this trend vanishes, and may reverse, at the lowest stellar masses, potentially reflecting the weaker host galaxy gravitational potentials. The offset AGN occupation fraction shows no significant evolution with orbital radius, and the agreement with predictions suggests a binary MBH formation rate of <0.5 per merger. Finally, for offset MBHs down to masses of 10^5 Solar masses, the occupation fraction is ~30-70 times lower than the expected value assuming all accreted satellites host a MBH. This result may suggest a relatively low MBH seeding efficiency.

We present the first infrared spectral predictions from a self-consistent simulation of the formation of a quasar in a starburst galaxy, spanning cosmological to innermost stable circular orbit (ISCO) scales. The infrared emission is dominated by a torus-like dust structure composed of the highly magnetized, turbulence-supported outer accretion disk and of accreting gas tidally torn from the interstellar medium (ISM). At these early stages, the AGN is buried and Compton-thick. The near- to mid-IR escaping luminosity varies by almost an order of magnitude across sightlines, largely due to extinction from the inflowing stream of cold dust. Self-absorption within the torus suppresses silicate emission features, and further reprocessing by the ambient ISM leads to prominent silicate absorption and colder IR emission. The sublimation structure is stratified by composition and size, producing sightline-dependent extinction curves that intrinsically vary in shape. However, after repeated scattering in the optically thick dusty medium, these curves emerge substantially grayed. We also demonstrate that bipolar outflows from the central black hole that carve biconical cavities and reveal the central engine in later stages can preserve IR anisotropy and silicate features. These results suggest that dusty starburst quasars can undergo a buried, IR-bright phase early in their evolution.

IceAct is an array of imaging air Cherenkov telescopes located at the ice surface above the IceCube Neutrino Observatory. Each telescope features a silicon photomultiplier based 61 pixel camera and a Fresnel-lens as imaging optic, resulting in a 12-degree field of view. The design is optimized to be operated in harsh environments, particularly at the South Pole. The setup will consist of seven telescopes in a so-called fly's eye configuration, increasing the field of view to 36^\circ, and an additional telescope 200m apart for stereoscopic observations. Rigorous testing procedures have been performed before deployment to ensure that operation under these conditions is possible, e.g. night sky observations and cold temperature tests. Furthermore, on-site calibrations are used to verify the accuracy and reliability of the installation. We derive the geometric alignment of each IceAct telescope by comparing the directional reconstruction of muons measured with IceCube to the corresponding primary particle direction reconstruction from IceAct. This contribution presents these testing procedures. Additionally, we present the on-site alignment calibration, including a Graph Neural Network reconstruction for the primary particle direction in IceAct, verification on Monte Carlo simulation, and the application to a commissioning dataset.

NASA's Habitable Worlds Observatory (HWO) aims to achieve starlight suppression to the $10^{-10}$ level for the detection and spectral characterization of Earth-like exoplanets. Broadband ozone absorption features are key biosignatures that appear in the 200-400nm near-ultraviolet (UV) regime. Extending coronagraphy from visible wavelengths to the UV, however, brings with it a number of challenges, including tighter requirements on wavefront sensing and control, optical surface quality, scattered light, and polarization aberrations, among other things. We aim to partially quantify and address these challenges with a combination of modeling, high-resolution metrology to the scales required for UV coronagraphy, and ultimately a demonstration of UV coronagraphy on the Space Coronagraph Optical Bench (SCoOB) vacuum testbed. In these proceedings, we provide a status update on our modeling and contrast budgeting efforts, characterization efforts to understand performance limitations set by key optical components, and our plans to move toward a demonstration of UV coronagraphy.

As the Vera Rubin Observatory begins its ten-year survey in 2025, it will probe key observables such as strong lensing (SL) by galaxies and clusters. In preparation for this new era, we assemble an extensive compilation of SL candidate systems from the literature, comprising over 30,000 unique objects that can be used as a watch list of known systems. By cross-matching this sample with photometric and spectroscopic catalogs, we construct two value-added tables containing key parameters for SL analysis, including lens and source redshifts and lens velocity dispersions $\sigma_v$. As a preparation for Rubin, we generate image cutouts for these systems in existing wide-field surveys with subarcsecond seeing, namely CFHTLens, CS82, RCSLens, KiDS, HSC, DES, and DESI Legacy. This sample, dubbed the "Last Stand Before Rubin" (LaStBeRu), has a myriad of applications, from using archival data to selections for follow-up projects and training of machine learning algorithms. As an application, we perform a test of General Relativity using these data, combining the effects of motion of massless particles (through SL modeling) and non-relativistic bodies through $\sigma_v$, which allow one to set constraints on the Post-Newtonian parameter $\gamma_\mathrm{PPN}$. Using the LaStBeRu database, we present an independent test of $\gamma_\mathrm{PPN}$ (distinct from previous analyses) and, for the first time, we present such a test exclusively with systems identifiable in ground-based images. By combining these data with the previously published samples, we obtain the most stringent constraint on $\gamma_\mathrm{PPN}$. Our results are consistent with GR at the $\sim$~1-$\sigma$ level and with the previous results from the literature.

Recent efforts to identify secondary variations in the Halo Occupation Distribution (HOD) have primarily focused on simulations examining the role of large-scale cosmic environments such as superclusters, filaments, and underdense regions or voids. If present, these variations could yield valuable insights into galaxy formation mechanisms, halo assembly processes, and the influence of external factors on cosmic structure. We aim to test whether secondary trends in the HOD driven by the large-scale structure of the Universe are detectable observationally. In particular, we examine whether the HOD depends on distance to key features of the cosmic web by explicitly quantifying these spatial relationships. We also analyze whether HODs vary across different cosmic environments, defined by critical point classifications, and assess the influence of intrinsic galaxy properties such as central galaxy color. We create volume-limited galaxy samples from SDSS-DR18 and use a group catalog to determine halo masses and identify central and satellite membership. Additionally, we employ a DisPerSE catalog to locate critical points such as maxima, minima, and filaments in the cosmic web. We evaluate how the HOD varies with proximity to these features and across five distinct cosmic environments. We further examine trends related to the color of central galaxies and test the robustness of our results with alternative DisPerSE catalogs generated using different smoothing scales and persistence thresholds. Our analysis shows that large-scale environments only weakly influence the HOD. However, second-order dependencies may be revealed through a multivariate approach that combines local and large-scale metrics with intrinsic galaxy properties. Future work with next-generation surveys and advanced modeling may achieve the precision required to detect and characterize these subtle environmental correlations.

The density distribution of supersonic isothermal turbulence plays a critical role in many astrophysical systems. It is commonly approximated by a lognormal distribution with a variance of $\sigma_{s,V}^2 \approx \ln(1 + b^2 M_{\rm V}^2),$ where $s \equiv \ln \rho/\rho_0,$ $M_{\rm V}$ is the rms volume-weighted Mach number, and $b$ is a parameter that depends on the driving mechanism, which can be solenoidal (divergence-free), compressive (curl-free), or a mix of the two. However, this neglects the correlation time of driving ($\tau_{\rm a}$), which plays a key role whenever compressive driving is significant. Here we conduct turbulence simulations spanning a wide range of Mach numbers, $1\lesssim M_{\rm V}\lesssim 10$, driving mechanisms, and $\tau_{\rm a}$ values. In the compressive case, we find that $\sigma_{s,V}^2$ scales approximately linearly with $M_{\rm V},$ and its dependence on $\tau_{\rm a}$ is $\sigma_{s,V}^2 \approx M_{\rm V} [1 + \frac{2}{3}(\lambda_{\rm a} + 1)\Theta(\lambda_{\rm a} + 1)]$, where $\lambda_{\rm a} \equiv \ln(\tau_{\rm a}/\tau_{\rm e})$, $\tau_{\rm e}$ is the eddy turnover time, and $\Theta$ is the Heaviside step function. Mixed-driven turbulence shows a weaker dependence on $\tau_{\rm a},$ and for solenoidally-driven turbulence, $\sigma_{s,V}^2 \approx \frac{1}{3}M_{\rm V}$, independent of $\tau_{\rm a}$ and consistent with the standard expression when $M_V \lesssim 10.$ The volume-weighted mean and skewness also show systematic trends with $M_{\rm V}$ and $\tau_{\rm a}$, deviating from lognormal expectations. For the mass-weighted density distribution, we observe significant broadening and skewness in compressively driven cases, especially at large $\tau_{\rm a}/\tau_{\rm e}$. These results provide a refined framework for modeling astrophysical turbulence.

The intrinsic variability of stars, due to acoustic oscillations, surface granulation, and magnetic activity, introduces radial velocity (RV) jitter in spectral lines, obscuring true planetary signals and hindering the detection of Earth-like planets. Granulation is particularly challenging, as it affects even the most inactive stars introducing substantial signals, with amplitudes up to 1 m/s. Disentangling granulation-induced RV jitter from signal caused by planetary reflex motion requires reliable models of stellar granulation. In this study, we present a new approach for calculating sensitivities of spectral lines to granulation. We simulate near-surface convection with 3D radiative MHD code MURaM and calculate high-resolution emergent spectra with the radiative transfer code MPS-ATLAS. We then introduce a novel methodology that uses spatial variability of spectral lines across the granulation pattern at a single moment in time to compute their temporal variability. This approach significantly reduces computational costs. We apply our approach to analyze the response of lines from neutral and singly ionized elemental species to solar this http URL find a clear distinction between the two groups of lines: those from neutral elements tend to show stronger variations in line strength, whereas those from singly ionized elements exhibit larger variations in central wavelength. These results enable the development of spectral line masks tailored to granulation sensitivity, offering a promising strategy to reduce granulation-induced RV noise and improve exoplanet detection.

We studied C/2025 D1 (Groeller), a long-period comet with an unprecedented perihelion distance of 14.1 au, using archival observations. The data reveals that it had been active at inbound heliocentric distances $r_{\rm H} \gtrsim 20$ au. Initially, the comet intrinsically brightened at $r_{\rm H} \gtrsim 16$ au, with brightening parameters comparable to those of other long-period comets. However, observations after late 2023 showed a gradual decay, despite the inbound trajectory of the comet. To our knowledge, such behaviours have not been observed for other long-period comets at similar heliocentric distances. We speculate that this might be linked to the onset of CO$_{2}$ sublimation and/or crystallisation processes. The surface brightness profile of the coma indicates a steady-state mass loss, implying supervolatile sublimation as the primary driver of the observed activity. Despite changes in the orbital plane angle, the circularly symmetric coma persisted throughout the observed period, indicative of the dominance of large grains in the coma. Assuming the activity trend is independent of bandpass, we found that comet was redder than many other solar system comets. Our model-dependent constraint estimates the nucleus radius to be $\gtrsim\!0.4$ km. We performed astrometric measurements, refined the orbital solution, and derived the original and future orbits of the comet. Our N-body integration, accounting for the Galactic tide, strongly favours that the comet is dynamically new, with its previous perihelion at $\gtrsim\!60$ au from the Sun $\gtrsim\!6$ Myr ago. It is highly likely that the comet will be lost from our solar system after the current apparition.

Clustering algorithms can help reconstruct the assembly history of the Milky Way by identifying groups of stars sharing similar properties in a kinematical or chemical abundance space. However, although being promising tools, their efficiency has not yet been fully tested in a realistic cosmological framework. We investigate the effectiveness of the HDBSCAN clustering algorithm in the recovery of the progenitors of Milky Way-type galaxies, using several systems from the Auriga suite of simulations. We develop a methodology aimed at improving the efficiency of the algorithm and avoiding fragmentation: First, we use a 12-dimensional feature space including a range of chemodynamical properties and stellar ages; furthermore, we optimise the algorithm using information from the internal structure of the clusters of accreted stars. We show that our approach yields good results in terms of both purity and completeness of clusters for galaxies with different types of accretion histories. We also evaluate the decrease in efficiency due to contamination by in situ stars. While for accreted-only haloes the algorithm matches well the recovered clusters with the individual progenitors and is able to recover accretion events up to a redshift of accretion $z_{\rm acc}\sim3$, for accreted + in situ haloes it can only identify the more recent accretion events ($z_{\rm acc} < 1$). However, the purity of the identified clusters remains remarkably high even in this case. Our results suggest that HDBSCAN can efficiently identify accreted debris in Milky Way-type galaxies in realistic conditions, however, it requires careful optimization to provide valid results.

Moons tidally interact with their host planets and stars. A close moon is quickly synchronised by the planet, or becomes captured in a higher spin-orbit resonance. However, the planet requires much more time to significantly alter its rotation rate under the influence of moon-generated tides. The situation becomes more complex for close-in planets, as star-generated tides come into play and compete with the moon-generated tides. Synchronisation of the planet by its moon changes the tidal dynamics of the entire star-planet-moon system and can lead to long-term stable configurations. In this paper, we demonstrate that a certain initial condition must be met for this to occur. Based on the angular-momentum conservation, the derived condition is universal and bears no dependence upon the planet's internal structure or tidal dissipation model. It is applicable to dwindling systems as well as tidally expanding orbits, and to the cases of initially retrograde motion. We present calculations for specific planet-moon systems (Earth and the Moon; Neptune and Triton; Venus and its hypothetical presently-extinct moon Neith; Mars, Phobos, and Deimos; Pluto and Charon), to constrain the dynamically plausible formation and evolution scenarios. Among other things, our analysis prompts the question of whether Pluto and Charon evolved into their current state from an initially more compact configuration (as is commonly assumed) or from a wider orbit -- a topic to be discussed at length elsewhere. Our results are equally applicable to exoplanets. For example, if asynchronous close-in exoplanets are detected, the possibility of tidal synchronisation by an exomoon should be considered.

The Be/X-ray pulsar 4U 0115+63 underwent a type II outburst in 2023. After the outburst, similar to the outbursts in 2015 and 2017, the source decayed into a quiescent state. Two out of three XMM-Newton observations conducted after the 2023 outburst confirmed the source to be in a low-luminosity state at a level of $L_{\rm X} \sim 10^{33}\,\rm erg\,s^{-1}$. X-ray pulsations were detected at $\approx$0.277 Hz in both observations with a pulsed fraction exceeding 50%. The power density spectra show no significant low-frequency red noise in both observations, suggesting that the radiation is not driven by accretion. The energy spectra in this state can be described by a single blackbody component, with an emitting area smaller than the typical size of the polar caps during the accretion phase. Based on the timing and spectral properties, we suggest that the propeller effect is active during the quiescent state, resulting in a total quenching of accretion. We discuss possible mechanisms for the generation of pulsations in this regime and consider the scenario of neutron star crust cooling.

Current population models of binary black hole distributions are difficult to interpret because standard population inferences hinge on modeling choices, which can mask or mimic real structure. The maximum population likelihood ``$\pistroke$ formalism'' provides a means to investigate and interpret features in the distribution of binary black holes using only data -- without specifying a population model. It tells us if features inferred from current population models are truly present in the data or if they arise from model misspecification. It also provides guidance for developing new models by highlighting previously unnoticed features. In this study, we utilize the $\pistroke$ formalism to examine the binary black hole population in the LIGO--Virgo--KAGRA (LVK) fourth Gravitational-Wave Transient Catalog (GWTC-4). Our analysis supports the existence of a gap around $45\,M_\odot$ in the secondary black hole mass distribution and identifies a widening in the distribution of the effective inspiral spin parameter $\chi_\text{eff}$ near this mass as recently reported by Tong et al. (2025). Similar to earlier studies, we find support for an anti-correlation between $\chi_\text{eff}$ and mass ratio. However, we argue that this may be a spurious correlation arising from misspecification of the joint distribution of black hole masses. Furthermore, we identify support for dimensionless black hole spin magnitudes at approximately $\chi \approx 0.2$ and $\chi\approx0.7$. The data support the existence of a correlation between the spin magnitudes $\chi_1$ and $\chi_2$, though subsequent study is required to determine if this feature is statistically significant. The accompanying data release includes $\pistroke$ samples, which can be used to compare theoretical predictions to LVK data and to assess assumptions in parameterised models.

Context. Medium-resolution IFS, such as MUSE at the VLT, are equipped to detect the emission lines of faint accreting companions when associated with dedicated stellar halo subtraction methods. We recently proposed a new approach based on polynomial modulations of a stellar spectrum estimate across the field of view, with orthogonal polynomials and lines masking. Aims. We seek to highlight and quantify analytically and on real data the benefits of this new approach over the one classically used, particularly with regard to distortions of the extracted spectra. Methods. We carried out analytical calculations based on simple toy models. Simulations of the most extreme situations identified were used to highlight these problems and corrections. Archival VLT/MUSE data of the young PDS70 and HTLup systems were used to vet the detection and characterization capabilities using on-sky observations. New images of the YSES1 planetary system were used to further illustrate the gains. Results. We show that the state-of-the-art method, based on low-pass filtering, can lead to the self-subtraction of the emission lines and modify the neighboring continua. We show that the proposed technique corrects these characterization problems, while maintaining the same detection capabilities. The two protoplanets PDS70 b and c were detected with 5sigma significance. The Halpha line estimate of the HTLup B stellar companion was improved by ~30% for the integrated flux and by ~8% for the 10%-width. As for YSES1 b, we found it uniquely displays a combination of Halpha, Hbeta, CaII H&K triplet, and HeI lines in emission. Conclusions. The proposed method better preserves the spectral information, notably the emission line fluxes and profiles, while achieving similar detection performance. Based on a linear and parametric approach, it can be extended and/or combined with additional faint signal search algorithms.

The W50 nebula around microquasar SS~433, powered by supercritical accretion, features two `extended jets' (tens of pc long and a few pc wide) from which polarized X-ray and very high energy radiation above 100 TeV is detected. Here we present a model of very high energy particle acceleration in these extended jets. In the `minimalist' model (discussed in Churazov, Khabibullin, and Bykov, 2024), a collimated outflow aligned with the rotation axis is propagating through a more isotropic wind produced by the accretion disk. The observed extended X-ray jets with bright knots in this model are associated with the formation of strong recollimation MHD shocks after the collision of the collimated outflow with the isotropic wind termination surface. The spectra of electrons and protons up to PeV energies are simulated with a nonlinear Monte Carlo model of diffusive shock acceleration with turbulent magnetic field amplification. The overall efficiency of the jets power transfer to accelerated protons in this model is above 10\% and about 0.5\% for electrons above 50 TeV. The magnetic field amplification by Bell's instability due to the electric current of cosmic rays escaping the accelerator produces highly anisotropic magnetic turbulence in the shock downstream. This results in the polarized synchrotron X-ray emission with the photon electric vector predominantly transverse to the jet direction and the degree of polarization above 20\%. The model is able to reproduce the observed spectra and intensity profiles of non-thermal X-ray and gamma-ray emission, which are both dominated by the leptonic radiation.

We present an investigation of the central structure of the S0 galaxy NGC 1553, to understand its origin and the underlying dynamical processes that shape it. The high-resolution integral field spectroscopic data from the Multi Unit Spectroscopic Explorer (MUSE) reveal a well-ordered rotation pattern, consisting of a rapidly rotating nuclear disc that is somewhat decoupled from the main disc, together with an inner lens; we collectively refer to these structures as the "disc-lens". The central peak in the velocity dispersion indicates the presence of a classical bulge. The nuclear disc is dynamically colder than the surrounding disc, while the lens is dynamically hotter. The higher-order Gauss-Hermite moments, $h_{3}$ and $h_{4}$, further characterise the stellar kinematics. An anti-correlation between the line-of-sight velocity and skewness ($h_{3}$) is consistent with regular rotation. In contrast, the ring-like enhancement in kurtosis ($h_{4}$) confirms the presence of the nuclear disc component. Unsharp masking of HST images (Erwin et al. 2015) reveals a nuclear bar and faint spiral structures within the central 10 arcsec, supporting the role of secular evolution. The mass-weighted stellar age map shows an old stellar population in the central regions, with high metallicity that suggests the in-situ formation of the disc-lens from disc material. We discuss possible formation scenarios for the disc-lens, including both minor mergers and secular processes, and examine the influence of the Dorado group environment on NGC 1553. Our findings suggest that the disc-lens in NGC 1553 formed during the early stages of the galaxy's evolution. However, its subsequent development has been shaped by internal and external processes. These results provide new insights into the origin and evolution of kinematically distinct substructures in S0 galaxies.

In this paper, we conduct a linear stability analysis of magnetized and/or rotating jets propagating in ambient matter that is also magnetized and/or rotating, having in mind the application to the jet penetrating the core/envelope of a massive star. We solve the linearized magneto-hydrodynamic (MHD) equations in the non-relativistic regime by Laplace transform in time and Fourier transform in space. In this formulation all unstable modes with the same translational and azimuthal wave numbers can be obtained simultaneously by searching for pole singularities in the complex plane. In order to determine unambiguously their driving mechanisms, we evaluate the second-order perturbation of the MHD Hamiltonian for individual eigenfunctions derived at these singular points. We identify in our non-rotating models the Kelvin-Helmholtz instability (KHI) as one of the shear-driven modes and the current-driven instability such as the kink instability (KKI). In rotational models we also find the magnetorotational instability (MRI) as another shear-driven mode. In some cases, we find that a mode changes its character continuously from KKI to KHI (and vice versa) or from MRI to KHI as the jet velocity is increased.

We investigate the aftermath of a giant quiescent solar filament eruption on December 24, 2023. One feature of the eruption is an extensive fan above the filament channel that is about three times as wide as similar structures that appear above active regions (ARs) during solar flares. The fan contains numerous supra-arcade downflows (SADs), and we investigate the largest SADs with continuous Hinode X-ray Telescope (XRT) observations. The measured maximum width of the SADs in this event is at least three times the maximum width of SADs observed in AR flares, whereas the velocities of the largest SADs are similar to the typical values of AR SADs. The kinetic characteristics of the largest SADs observed in this event align with previous model predictions, where SADs originate from the non-linear development of Rayleigh-Taylor type instabilities. In this scenario, the larger system size allows the existence of larger-scale instabilities, while the development of the velocities of these instabilities is expected to be independent of the system size. Compared to AR flares, the temperature and emission measure in this event are lower, and there is less overall radiation, resulting in no evident Geostationary Operational Environmental Satellite (GOES) signature. Similar to those in AR flares, SADs show lower temperatures compared to the surrounding fan plasma. Our observations show that SADs are present in a wide variety of eruptions. The reconnection mechanisms present in quiescent filament eruptions are similar to those driving more compact eruptions originating from ARs.

The expansion of the Universe is the basis of modern cosmology. This chapter outlines the theory behind the expansion of the universe, including the cosmological principle, distances, velocities, and accelerations. We provide basic derivations of the key equations and highlight some interesting features, such as superluminal expansion, how pressure increases gravitational attraction, the subtleties of conservation of energy in the expanding universe, and the existence of cosmological horizons.

The large-scale convection in the Sun known as supergranulation is manifested as a network structure on the solar surface. The network cells have an average lifetime of 24 hr, a size of about 30 Mm, and a lane width of about 6 Mm. We have obtained the lane widths and intensities at different latitudes from the Ca {\sc ii} K spectroheliograms from the 100 yr Kodaikanal archival data. We have then calculated the cross correlation function of lane widths and intensities with sunspot number at every latitude from 60$^{\circ}$ N to 60$^{\circ}$ S. The correlation coefficients of the quantities show an approximate North-South symmetry with broad peaks around $\pm$(11--22)$^{\circ}$ latitude with values of about 0.8. The results imply that these latitudes follow the sunspot cycle strongly. The maximum correlation for the lane widths occurs (18$\pm$2)$^{\circ}$ N and (20$\pm$2)$^{\circ}$ S with no phase difference. For intensities, this happens at (13$\pm$2)$^{\circ}$ N and (14$\pm$2)$^{\circ}$ S with a phase difference of 1.25 to 1.5 yr. It is interesting to note that the lane width correlations peak during the solar maximum whereas the intensitiy correlations peak 1.25--1.5 yr after the solar maximum. The results, generally show that no unique latitude exactly follows the solar cycle for all quantities. The results are important in flux transport on the solar surface and have implications for the quiet Sun UV irradiance variations.

Time-delay cosmology offers an alternative approach to measuring the Hubble constant ($H_0$), which is distinct from the cosmic distance ladder and cosmic microwave background radiation methods. In this study, we present an improved strong lens mass modeling analysis of the cluster-lensed supernova Refsdal, incorporating the latest spectroscopic redshift data from the MUSE on the Very Large Telescope and the James Webb Space Telescope CANUCS/Technicolor. The robustness of our lens models is confirmed using the Jackknife method. From our analysis that considers four lens mass models with different assumptions on profiles of dark matter halos and external perturbations, we derive a constraint on the Hubble constant of $H_0=66.0\pm{4.3}\Mpc$ after combining best-fitted values of the four lens models.

Dwarf novae are a subset of cataclysmic variables that accrete material intermittently in short-duration outbursts with sometimes long quiescent intervals in between. During the quiescent state, the white dwarf (WD) photosphere may be observable. Some of these systems show periodic variability consistent with a non-radial oscillation. Asteroseismology has become a unique tool for the measurement of internal structure of the WDs, such as their masses, radii, temperatures and rotation profiles. A few stable periodicities have been observed for accreting WDs, but the lack of complete and accurate theoretical models has hindered the real diagnosis of the observed pulsations. Though the associated pulsations in accreting WDs are thought to be $g$-modes, some work in the literature suggests that these pulsations could be Rossby modes ($r$-modes). Here, to elucidate this, we present a first simultaneous analysis of $g$- and $r$-mode pulsations in accreting white dwarfs including a full computation of visibility accounting for the distribution of variation over the WD surface. We show that, up to the second lowest degree ($\ell =2$), neither $g-$ nor $r$-modes have a clear advantage in visibility. Although a few retrograde $r$-mode orders exhibit a larger visibility, the low-order $g$ modes possess higher frequency in the star's frame, making them more likely to be driven within the convective driving scenario commonly applied to isolated WDs. Therefore, we favor a $g$-mode origin for the observed periods in accreting WDs, though $r$-modes will be important for stars with more observed modes.

We consider effects of the harmonic magnetic field boundary conditions at the top of the dynamo domain on the dynamo stability inside the solar convection zone. These boundary conditions allow us to quantify the helical properties of the coronal magnetic field that stems from the dynamo region. In sewing the tangential component of the mean electric field we are able to take into account the effect the diffusive properties of the stellar corona on the dynamo instability. The model shows that effect of the vacuum boundary conditions can be restored if we introduce a few orders of magnitude jump of the coronal magnetic field turbulent diffusion over its typical value at the top of the dynamo domain. The parameters of this jump define the critical instability threshold of the $\alpha$ effect in the $\alpha^{2}\Omega$ dynamo.

The coronal soft X-ray emission of cool stars, especially when taken in combination with their measured rotation periods, offers insights into their levels of magnetic activity and related transitions. We study the X-ray properties of low-mass members of the open cluster NGC 2516 to explicate their detailed dependencies on mass and rotation. We analysed the pointed SRG/eROSITA satellite observations of NGC 2516 obtained during the calibration and performance verification phase of the mission. We found 1561 X-ray sources within the field of view and related 1007 of them to their optical stellar counterparts, including 655 members of NGC 2516 (433 with rotation periods). We combined these detections with auxiliary optical data to facilitate their interpretation. Furthermore, we extracted X-ray spectra for all sources and fit two-component APEC models to them. To aid the analysis, we grouped stars with similar mass and rotational properties together, which allowed us to investigate the influence of rotation on various X-ray properties. The colour-activity diagram of NGC 2516 displays a general increase in the fractional X-ray luminosity with spectral type change from F through G and K to M-type. However, the behaviour of K-type stars, representing the ones that best sample the fast-to-slow rotational transition, is more complex, with both increased and decreased X-ray emission relative to G-type stars for fast and slow rotators, respectively. The rotation-activity diagram is analogous, with an identifiable desaturated group of X-ray emitters that corresponds to stars in the rotational gap between the fast and slow rotator sequences. We prefer to describe the normalised X-ray emission for all cluster stars as declining logarithmically with Rossby number over those using broken power laws. Coronal temperatures appear to be largely independent of mass or rotation. (abridged)

During a giant eruption of a very massive star in the binary system, the companion star can accrete a large amount of mass that can change its properties and potentially its subsequent evolution. The effect depends on the companion mass, metallicity, the amount of mass it accreted, orbital parameters and other parameters. We simulate individual companion stars assuming they undergo such accretion events. We study the envelope properties of 20 $\rm M_\odot$ and 30 $\rm M_\odot$ single massive stars at different matallicities ($Z= 0.02$, $Z=0.008$ and $Z=0.004$) during accretion at different rates, from $\rm 10^{-5}$ to $\rm 10^{-2}~M_\odot\,yr^{-1}$. For the lower accretion rates we simulate, the stars remains hot, while at higher accretion rates, it becomes cooler and inflates. This behavior is observed in both stars but occurs at different accretion rates. Higher metallicity stars exhibit greater variations in accretion luminosity for the same accretion rate and stellar mass compared to lower metallicity stars. While higher metallicity stars typically have larger stellar envelopes, suggesting smaller variations in luminosity at Galactic metallicity compared to the LMC and SMC, our results show the opposite.

An approximate analytical solution for the rotating twisted magnetosphere of magnetars is presented. The poloidal flux is approximated by the self-similar twisted dipole field. The toroidal field is obtained by the minimum torque model. Under this approximation, it is found that: (1) The Y-point radius decreases with the increase of twist of the magnetic field. (2) The polar cap is larger for larger twist. (3) The particle outflow luminosity is larger for larger twist. (4) The maximum acceleration potential, pulse width of magnetar radio emission etc all increase with the twist. (5) For an untwisting magnetosphere, the physical properties general evolves towards that of the normal pulsars. The above findings are consistent with previous analytical and numerical results. The larger polar cap may corresponds to the hot spot during magnetar outburst. In general, a rotating twisted magnetosphere has larger open field line regions. The radio emission of magnetars and fast radio burst may both originates in the larger and evolving open field line regions of magnetars.

PSR B1259-63 is a classical gamma-ray binary detected from radio to TeV energies near periastron. In the GeV band, it had previously been detected only up to a few GeV, with the extrapolation of the TeV spectrum overestimating the measured GeV flux. Using over 17 years of Fermi-LAT observations, we report the first detection of PSR B1259-63 in the 10 GeV to $\gtrsim 100$ GeV range, from -400 to +100 days relative to periastron. The Fermi-LAT spectrum is well described by a hard power law with index $\Gamma = 1.9 \pm 0.1$, and has a flux level consistent with that measured at TeV energies by H.E.S.S. The apparent transition from the hard Fermi-LAT spectrum to the softer TeV spectrum suggests that the detected GeV emission traces the rising tail of the inverse-Compton component extending into the TeV regime. We note that the detection of PSR B1259-63 as early as -400 days before periastron is difficult to reconcile with existing theoretical models.

Mars finished forming while the solar nebula was still present, and acquired its primordial atmosphere from this reservoir. The absence of a detectable cometary xenon signature in the present-day Martian atmosphere suggests that the capture of solar nebular gas was significant enough to dilute later cometary contributions. By quantifying the mass of cometary material efficiently retained on Mars, we place a lower bound on the mass of the primordial Martian atmosphere. To test the robustness of our conclusions, we use cometary bombardment data from two independent studies conducted within a solar system evolutionary model consistent with its current structure. Our calculations show that, even under the most conservative scenario, the minimal mass of the primordial martian atmospheres would yield a surface pressure of no less than 2.9 bar. Such a massive nebular envelope is consistent with recent models in which atmospheric capture is strongly enhanced by the presence of heavier species on Mars - due to outgassing or redox buffering with a magma ocean.

Recent discoveries of dust and molecular gas in quiescent galaxies (QGs) up to $z\sim3$ challenge the long-standing view that the interstellar medium depletes rapidly once star formation ceases, raising key questions of whether dust and gas co-evolve in QGs, and how their depletion links to stellar aging. We present deep Atacama Large Millimeter/submillimeter Array (ALMA) Band~6 continuum and CO(3--2) observations of 17 QGs at $z\sim0.4$ in the COSMOS field. Using the dust-to-molecular gas mass ratio ($\delta_{\rm DGR}$) as a key diagnostic, we trace post-quenching evolution of the cold interstellar medium. Our study triples the number of QGs with direct $\delta_{\rm DGR}$ estimates, constraining 12 systems with stellar population ages of $\sim$5--10 Gyr. For the first time, we show that $\delta_{\rm DGR}$ in QGs ranges from $\sim8\times$ below to $\sim2.5\times$ above the canonical value of $\delta_{\rm DGR}\sim1/100$. Despite uniformly low molecular gas fractions (median $f_{\rm H_2}=M_{\rm H_2}/M_{\star}\sim4.1\%$), QGs follow diverse evolutionary paths: about half exhibit rapid ($\sim700$ Myr) exponential dust decline with age, while the rest show mild decline over $\gtrsim$2 Gyr, maintaining elevated $\delta_{\rm DGR}\gtrsim1/100$. Our results support simulations predictions of dust and molecular gas evolving independently post-quenching, without a preferred quenching mode. This challenges the use of dust continuum as a $\rm H_2$ tracer, implying that quenching cannot be robustly linked to interstellar medium conditions when relying solely on dust or gas.

We investigate the solar origin and heliospheric evolution of an intense geomagnetic storm that occurred on March 23-24, 2023. Despite multiple candidate CMEs observed between March 19-21, a weak CME detected on March 19 at 18:00 UT was identified as the cause, originating from the eruption of a longitudinal-filament channel near center of the sun. The channel underwent a smooth transition to eruption phase without detectable low coronal signatures. Wide-angle heliospheric imaging revealed asymmetric expansion and acceleration by solar wind drag, achieving an average CME velocity of $\approx$640 km/s. The radial evolution of the interplanetary coronal mass ejection (ICME) was analyzed by three spacecraft in close radial alignment. Arrival times and propagation speeds were consistent across spacecraft, with a 21 hour delay between STEREO-A and WIND attributed to solar rotation and longitudinal separation. The ICME exhibits magnetic cloud (MC) signatures characterized by right-handed helicity, enhanced density at all three spacecraft. The MC underwent expansion (radial-size increases from 0.08AU at SolO to 0.18AU at STEREO-A), decrease in magnetic field strength with distance; $B_{av}\propto R_H^{-1.97}$ (SolO-STA) and $B_{av}\propto R_H^{-1.53}$ (SolO-WIND). The MC axis is inclined with the ecliptic at $-69^o$ at SolO, $-25^o$ at STA and $-34^o$ at WIND, indicating rotation during heliospheric transit. Importantly, the storm's main phase leads to a peak intensity ($SYM-H=-169$nT) occurring at 24/02:40UT followed by a second peak ($SYM-H=-170$nT) at 24/05:20UT due to density enhancement towards MC's tail. The study emphasizes the significant geoeffectiveness of weak, stealth CMEs with southward Bz and density enhancements.

X-ray burst oscillations are quasi-coherent periodic signals at frequencies close to the neutron star spin frequency. They are observed during thermonuclear Type I X-ray bursts from a number of low-mass X-ray binaries (LMXBs) hosting a fast-spinning, weakly magnetic neutron star. Besides measuring the spin frequencies, burst oscillations hold the potential to accurately measure neutron star mass and radius, thus providing constraints on the equation of state of matter at nuclear densities. Based on far-ultraviolet (FUV) observations of the X-ray binary EXO 0748-676 taken with the Hubble Space Telescope in 2003, we report a possible indication of ultraviolet burst oscillations at the neutron star spin frequency ($\sim$552 Hz), potentially the first such case for an LMXB. The candidate signal is observed during an $\sim$8 s interval in the rising phase of an FUV burst, which occurred $\sim$4 s after a Type I X-ray burst. Through simulations, we estimated that the probability of detecting the observed signal power from pure random noise is 3.7$\%$, decreasing to 0.3$\%$ if only the burst rise interval is considered, during which X-ray burst oscillations had already been observed in this source. The background-subtracted folded pulse profile of the candidate FUV oscillations in the (120-160 nm) band is nearly sinusoidal with a $\sim$16$\%$ pulsed fraction, corresponding to a pulsed luminosity of $\sim$8$\times$10$^{33}$ erg/s. Interpreting the properties of this candidate FUV burst oscillations in the light of current models for optical-ultraviolet emission from neutron star LMXBs faces severe problems. If signals of this kind are confirmed in future observations, they might point to an unknown coherent emission process as the origin of the FUV burst oscillations observed in EXO 0748-676.

While the James Webb Space Telescope (JWST) now allows identifying quiescent galaxies (QGs) out to early epochs, the photometric selection of quiescent galaxy candidates (QGCs) and the derivation of key physical quantities are highly sensitive to the assumed star-formation histories (SFHs). We aim to quantify how the inclusion of JWST/MIRI data and different SFH models impacts the selection and characterisation of QGCs. We test the robustness of the physical properties inferred from the spectral energy distribution (SED) fitting, such as M*, age, star formation rate (SFR), and AV, and study how they impact the quiescence criteria of the galaxies across cosmic time. We perform SED fitting for ~13000 galaxies at z<6 from the CEERS/MIRI fields with up to 20 optical-mid infrared (MIR) broadband coverage. We implement three SFH prescriptions: flexible delayed, NonParametric, and extended Regulator. For each model, we compare results obtained with and without MIRI photometry and dust emission models. We evaluate the impact of these configurations on the number of candidate QGCs, selected based on rest UVJ colours, sSFR and main-sequence offset, and on their key physical properties such as M*, AV, and stellar ages. The number of QGCs selected varies significantly with the choice of SFH from 171 to 224 out of 13000 galaxies, depending on the model. This number increases to 222-327 when MIRI data are used (up to ~45% more QGCs). This enhancement is driven by improved constraints on dust attenuation and M*. We find a strong correlation between AV and M*, with massive galaxies (M*~10^11 M\odot) being 1.5-4.2 times more attenuated in magnitude than low-mass systems (M*~10^9 M\odot), depending on SFH. Regardless of the SFH assumption, ~13% of QGCs exhibit significant attenuation (AV > 0.5) in support of recent JWST studies challenging the notion that quiescent galaxies are uniformly dust-free.

While cosmic reionization has been broadly constrained by global observables, the interplay between internal sources (Milky Way, M31, and their satellites) and external ionization fronts remains poorly understood in a realistic Local Group (LG) context. To address this issue, we perform radiative transfer post-processing on the original HESTIA LG constrained simulation. We calibrate our source models using a uniform 1024^3 particle, dark-matter only, HESTIA simulation coupled with a subgrid collapse-fraction model to match the global reionization observables. These source models are then applied to the HESTIA zoom-in simulations, which consist of a 4096^3 particle effective resolution in the zoom region centered on the Milky Way (MW) and M31 haloes, which resolves haloes down to 10^8 solar masses. We find that in all scenarios, reionization within the LG proceeds in an inside-out manner with the progenitors of the MW and M31 having 50 percent of their material ionized by z ~ 9-8.6, significantly earlier than the global midpoint at z ~ 7-7.7, noting that external fronts from large-scale structure play a negligible role, even under the most permissive feedback model. We further show that present-day satellite galaxies exhibit only a weak correlation between their reionization redshift and their present-day radial distance from their host halo, with somewhat tighter trends around M31 than the MW. Finally, we find that satellites which assembled before reionization are systematically more massive today, suggesting that the oldest stellar populations preferentially reside in the most massive subhaloes.

TOI-1203 is a bright (V=8.6) G3 V star known to host a transiting warm sub-Neptune on a 25.5 d orbit. Here we report on an intensive high-precision radial velocity and photometric follow-up campaign carried out with the HARPS spectrograph and the CHEOPS space telescope. We found that TOI-1203 has an enhancement of $\alpha$ elements relative to iron of [$\alpha$/Fe]=$0.21\pm0.04$. With an age of $\sim$12.5 Gyr, TOI-1203 belongs to the old, $\alpha$-element enhanced stellar population of the galactic thick disk. We spectroscopically confirmed the planetary nature of the 25.5 d sub-Neptune TOI-1203 d, measured its mass ($M_{d}=7.39\pm0.62~M_{\oplus}$) and refined its radius ($R_{d}=2.918_{-0.045}^{+0.046}~R_{\oplus}$). We discovered the presence of an additional transiting super-Earth on a 4.2 d orbit (TOI-1203 b) with a mass of $M_{b}=3.51_{-0.32}^{+0.33}~M_{\oplus}$ and a radius of $R_{b}=1.520_{-0.046}^{+0.045}~R_{\oplus}$. We also revealed the presence of two additional low-mass planets at 13.1 d and 204.6 d (TOI-1203 c and e), with minimum masses of $5.46_{-0.50}^{+0.51}~M_{\oplus}$ and $42.10_{-1.78}^{+1.83}~M_{\oplus}$. We found that the outer planet TOI-1203 e lies on an eccentric orbit with $e_{e}=0.152\pm0.029$. We performed a stability analysis of the system confirming that there are configurations consistent with the observed parameters that are dynamically stable over billion-year timescales. While analyzing the HARPS time series, we discovered that the FWHM of the HARPS cross-correlation function shows a significant long-period signal ($\sim$615 d) that has no counterpart in the radial velocity data or in the remaining HARPS ancillary time series. We significantly detected the same signal in the FWHM of the Th-Ar calibration lines used to compute the nightly wavelength solution, and attributed this systematic effect to a long-term variation of the HARPS instrumental profile.

In this study, we report conclusive evidence for an ancient star cluster that has been accreted by the Large Magellanic Cloud (LMC). By leveraging observations from the Hubble Space Telescope (HST), we investigate the chrono-dynamical structure of a sample of seven old star clusters within the LMC in a self-consistent way. The multi-epoch nature of the dataset allowed the determination of high-precision proper motions for the clusters. Employing an isochrone-fitting methodology, we additionally infer from the deep high-resolution HST data homogeneous and robust estimates for their distances, ages and metallicities. Supplementing these data with literature line-of-sight velocities, we investigate the full 3-dimensional dynamics of the clusters within the frame of the LMC. With respect to the other clusters in our sample, NGC 1841 depicts a peculiar case. Its position in the age-metallicity plane, that makes it about 1 Gyr younger than the other metal-poor LMC clusters, but also its dynamical properties with a radial orbit almost perpendicular to the LMC disc plane, clearly advocates for a different origin. We thus conclude that NGC 1841 has likely been accreted by the LMC from a smaller galaxy. The other clusters in our sample show disc-like kinematics, with the case of NGC 2210 being peculiar, based on its inclined orbit. Their coherent age-metallicity relation closely resembles that of Gaia-Sausage-Enceladus globular clusters, thus suggesting a similar early evolution for the two dwarf galaxies. We do not find clear-cut chrono-kinematic evidence that NGC 2005 has been accreted by the LMC as suggested by a previous study based on its chemical abundance pattern. Regardless of its nature, its very old age illustrates that peculiar chemical evolutions already emerge at very early times.

The signatures of waves are seen during many high-quality ground-based refractive stellar occultations by solar system atmospheres. We present a new forward-modeling technique for ground-based stellar occultations based on wavelet decomposition. If profiles of refractivity are written as the product of an exponential and a wavelet decomposition, then we can analytically write the profiles of the bending angles and the bending angle derivatives that are needed to calculate occultation light curves. Requiring that the atmosphere is statically stable places limits on the amplitudes of atmospheric waves and their effect on the observed light curve.

Electromagnetic and gravitational-wave signals from neutron stars are shaped by rapid rotation and strong magnetic fields. Determining these properties is essential to interpret such signals, but current measurements are limited: rotation estimates rely on electromagnetic detections and assume uniform rotation, while inferring interior magnetic fields remains ambiguous due to a lack of direct observations. Measuring the excited fundamental modes of neutron stars in gravitational-wave signals offers a promising solution, as these modes encode information about stellar composition, structure, and dynamics. Previous studies have examined the individual effects of rotation and magnetic fields on these modes, identifying magnetic suppression and establishing linear relations for the frequencies of the fundamental $l=0$ quasi-radial mode $f_F$ and $l=2$ quadrupolar mode $f_{^2f}$. However, few have investigated the combined influence of rotation and magnetic fields. Here, for the first time, we consider both rotation and a toroidal magnetic field to construct linear relations for quantifying $f_F$ and $f_{^2f}$, showing that their combined effects can be constrained by detecting these modes. Using 2D axisymmetric simulations, we demonstrate that quasi-linear relations between $f_F$, $f_{^2f}$, stellar compactness $M/R$, and kinetic-to-binding energy ratio $T/|W|$ persist even with a toroidal magnetic field. The slope of these relations depends on the toroidal magnetization constant $K_\mathrm{m}$. Additionally, measuring the frequency ratio $f_{^2f}/f_F$ enables inference of $T/|W|$ and the maximum magnetic field strength $\mathcal{B}_\mathrm{max}$. Lastly, we show that differential rotation causes only minor deviations from predictions for uniform rotation. Thus, this work demonstrates that rotational and magnetic properties of neutron stars can be inferred from their fundamental modes.

Distance measurements using the planetary nebula luminosity function (PNLF) rely on the bright-end power-law cut-off magnitude ($M^*$), which is defined by a number of the [OIII]$\lambda5007$-brightest planetary nebulae (PNe). In early-type galaxies (ETGs), the formation of these PNe is enigmatic; the population is typically too old to form the expected $M^*$ PNe from single star evolution. We aim to give a solution to this problem. We selected five ETGs with known MUSE-PNLF distances. The MUSE instrument allows us to calculate the PNLF and consistently investigate the underlying stellar populations. Using stellar population synthesis, we derive the population age, star formation history, metallicity, and alpha abundance. We compare these parameters to the PNLF variables: $M^*$ and luminosity-specific PN number at the top 0.5 mag of the PNLF ($\alpha_{0.5}$). We also compare our results with PNe In Cosmological Simulations (PICS) model applied to Magneticum Pathfinder analogue galaxies. The average mass-weighted ages and metallicities of our observations are typically old ($9 <\mathrm{Age}< 13.5$ Gyr) and rather metal-rich ($-0.4 <\mathrm{[M/H]}< +0.2$). We find $M^*$ to be independent of age and metallicity in these ages and metallicity intervals. We discover a positive correlation between $\alpha_{0.5}$ values and the mass fraction of stellar population ages of 2--10 Gyr, implying that most of the PNe originate from stars with intermediate ages. Similar trends are also found in the PICS analogue galaxies. We show that the presence of at least $\sim 2\%$ of stellar mass younger than 10 Gyr is, in principle, sufficient to form the $M^*$ PNe in ETGs. We also present observing requirements for an ideal PNLF distance determination in ETGs.

The energy equilibrium between the corona and the underlying disk in a two-phase accretion flow sets a lower limit on the achievable photon index. A slab corona may not explain the hard state observations of X-ray binaries (XRBs). We incorporate energy feedback to the accretion disk resulting from illumination by an extended corona, and vice versa. The interaction between these two components allows for the possibility of finding an energetically self-consistent equilibrium solution for a given disk-corona system. We have upgraded the existing Monte Carlo radiative transfer code, MONK, to incorporate the interaction between the disk and the extended corona within the general relativistic framework. We introduce an albedo parameter to specify the fraction of the incident flux that is reflected by the disk, while the remainder is absorbed and added to the intrinsic dissipation. Reflection is modeled assuming a semi-infinite electron atmosphere. We find global equilibrium solutions by iterating interaction between disk and extended slab corona. A higher black hole spin, higher coronal temperature, and higher albedo all lead to harder spectra. For typical coronal temperatures and disk albedo, the lowest achievable photon index with a static slab corona fully covering the disk is approximately 1.7-1.8. With the upgraded version of MONK, we are now able to achieve global energy equilibrium for a given disk-corona system. This approach holds significant potential for constraining the coronal geometry using not only the observed flux but also polarization. A static slab does not appear to be a favorable coronal geometry for the hard state of XRBs, even when global energy balance is taken into account. In future work, we will explore truncated disk geometries and outflowing coronae as potential alternatives. (shortened)

The ambipolar electrostatic field has long been recognized as a key driver of ion escape from planetary atmospheres. Elucidating the mechanisms responsible for the generation of this field is critical for understanding atmospheric escape and the evolution of habitability on terrestrial planets. Yet, existing comparisons between ambipolar diffusion theory and in-situ potential measurements have largely neglected the effect of electron heat flow. Confronting the theory incorporating heat-flow effect with in-situ electrical potential data from the \textit{Endurance} sounding rocket mission, we identify observational signatures of electron heat-flow effects. Furthermore, the implications of electron heat-flow effect across terrestrial planets are revealed, focusing on its capacity to resolve the enigma of Venusian electric potential drop anomaly. The anisotropic ion temperatures and the associated enhancement of electron heat-flow effect can explain the anomalous electric potential drop observed in the ionosphere of Venus.

High-mass X-ray binaries (HMXBs) are systems in which a neutron star or black hole accretes material from a massive companion. HMXBs are expected to have experienced a supernova in their evolution. The impulsive kick associated with this event should affect the space velocity of the system in a way that depends on the nature and state of the progenitor binary. Here, we test whether the different evolutionary histories of HMXBs have left a detectable imprint on their peculiar velocities ($V_{\rm pec}$). Using data from Gaia Data Release 3 (Gaia DR3), we first calculate the $V_{\rm pec}$ values for 63 well-known HMXBs hosting a black hole or neutron star and estimate the associated uncertainties via Monte Carlo re-sampling. We then analyse their distribution and check for differences between classes. Overall, $V_{\rm pec}$ estimates extend up to 100 km s$^{-1}$, but with Be/X-ray binaries (BeXRBs) favouring $V_{\rm pec}$ $\lesssim 40$ km s$^{-1}$ and supergiant X-ray binaries (SgXRBs) favouring $V_{\rm pec}$ $\gtrsim 40$ km s$^{-1}$. Based on a Kolmogorov-Smirnov (K-S) test, the null hypothesis that the peculiar velocities of both classes are drawn from the same parent distribution can be robustly rejected, irrespective of the background stellar velocity dispersion. Tests with binary population synthesis demonstrate that SgXRBs typically have shorter orbital periods and higher fractional mass loss than BeXRBs at supernova. We argue that the magnitude of $V_{\rm pec}$ could be used as a complementary feature to distinguish between Be and supergiant systems. These findings extend previous inferences based on two-dimensional kinematics from Hipparcos, and may be explained by the differing nature of the respective progenitors systems between the source classes at the instant of supernova.

In anticipation of upcoming cosmological surveys, we use the large volume Flamingo hydrodynamical simulations to look for signatures of dynamical activity, focusing on the hot gas profiles of groups and clusters out to redshift $z=1$. To determine the dynamical state of each object, we consider the halo mass accretion rate, $\Gamma$, as well as three observational proxies: stellar mass gap, $\Mstar$; X-ray concentration, $c_\mathrm{x}$, and X-ray centroid shift, $\left<w\right>$. In general, the median values of these indicators vary in accordance with an increase in dynamical activity with both mass and redshift. We find $\left<w\right>$ to be the most reliable proxy, while $c_\mathrm{x}$ and $\Mstar$ are more sensitive to resolution and feedback model details. Looking at the profiles, the correlation between dark matter density and $\Gamma$ has a characteristic radial dependence, being negatively (positively) correlated at small (large) radii. This trend is insensitive to both halo mass and redshift. Similar behaviour is also seen for the hot gas densities in low redshift clusters, particularly when using $\left<w\right>$, but the correlations become weaker in groups, at higher redshift and when stronger feedback is employed. We also find the intrinsic scatter in the gas density profiles to decrease with redshift, particularly in groups, contrary to what is seen for the dark matter. Interestingly, the radius of minimum gas density scatter increases with feedback strength, suggesting that this property could be a useful feedback diagnostic in future observational studies.

X-rays emitted by high mass X-ray binaries (HMXBs) and supernovae-driven winds in the first galaxies during Cosmic Dawn are expected to warm the intergalactic medium prior to its reionization. While most of the heating will be uniform on measurable scales, exceptionally bright sources will produce a warm ring around them with a distinctive 21-cm signature. The detection of such systems would confirm X-rays are a source of IGM heating during Cosmic Dawn and provide a test of models predicting higher X-ray luminosities per star formation rate compared with present-day galaxies. We illustrate the effect for a star-forming galaxy in a $10^{11}\, M_\odot$ halo at $z=12$, treating the photoionizing radiation and X-rays using a novel fully time-dependent 3D ray-tracing radiative transfer code. We consider a range in possible spectra for the HMXBs and star formation efficiencies, as well as the possible effect of an extended halo around the galaxy. We find detection of the signal would require integration times of a few thousand hours using SKA1-Low except for a bright galaxy like a starburst, but only a thousand hours for the expected noise levels of SKA2-Low. Depending on the surrounding gas density profile, the 21-cm signature of X-ray heating may still require an exceptionally high star formation rate, either intrinsic to the source or provided by other systems clustered near it, to avoid dominance of the signal by absorption from the surrounding gas.

The main accretion phase of protostars is characterized by the ejection of material in the form of jets/outflows. External UV irradiation can potentially have a significant impact on the excitation conditions within these outflows. High-resolution observations in the mid-infrared allow us to investigate the details of those energetic processes through the emission of shock-excited H$_2$ . Our aim is to spatially resolve H$_2$ and ionic/atomic emission within the outflows of low-mass protostars, and investigate its origin in connection to shocks influenced by external ultraviolet irradiation. We analyze spectral maps of 5 Class I protostars in the Ophiuchus molecular cloud from the James Webb Space Telescope (JWST) Medium Resolution Spectrometer (MIRI/MRS). Four out of five protostars show strong H$_2$, [\ion{Ne}{II}], and [\ion{Fe}{II}] emission associated with outflows/jets. Pure rotational H$_2$ transitions from S(1) to S(8) are found and show two distinct temperature components on Boltzmann diagrams with rotational temperatures of $\sim$500-600 K and $\sim$1000-3000 K respectively. Both $C$-type shocks propagating at high pre-shock densities (n$_\text{H} \ge$10$^4$ cm$^{-3}$) and $J$-type shocks at low pre-shock densities (n$_\text{H} \le$10$^3$ cm$^{-3}$) reproduce the observed line ratios. However, only $C$-type shocks produce sufficiently high column densities of H$_2$, whereas predictions from a single $J$-type shock reproduce the observed rotational temperatures of the gas better. A combination of various types of shocks could play a role in protostellar outflows as long as UV irradiation is included in the models. The origin of this radiation is likely internal, since no significant differences in the excitation conditions of outflows are seen at various locations in the cloud.

Monitoring the abundance of greenhouse gases (GHGs) such as carbon dioxide (CO$_2$) and methane (CH$_4$) is necessary to quantify their impact on global warming and climate change. Although a number of satellites and ground-based networks measure the total column volume mixing ratio (VMR) of these gases, they rely on sunlight, and column measurements at night are comparatively scarce. We present a new algorithm, Astroclimes, that hopes to complement and extend nighttime CO$_2$ and CH4 column measurements. Astroclimes can measure the abundance of GHGs on Earth by generating a model telluric transmission spectra and fitting it to the spectra of telluric standard stars in the near-infrared taken by ground-based telescopes. A Markov Chain Monte Carlo (MCMC) analysis on an extensive dataset from the CARMENES spectrograph showed that Astroclimes was able to recover the long term trend known to be present in the molecular abundances of both CO$_2$ and CH$_4$, but not their seasonal cycles. Using the Copernicus Atmosphere Monitoring Service (CAMS) global greenhouse gas reanalysis model (EGG4) as a benchmark, we identified an overall vertical shift in our data and quantified the long term scatter in our retrievals. The scatter on a 1 hour timescale, however, is much lower, and is on par with the uncertainties on individual measurements. Although currently the precision of the method is not in line with state of the art techniques using dedicated instrumentation, it shows promise for further development.

Galaxy evolution theories require co-evolution between accreting supermassive black holes (SMBH) and galaxies to explain many properties of the local galaxy population, yet observational evidence for the mechanisms driving this co-evolution is lacking. The recent star-formation histories of the host galaxies of accreting SMBHs (Active Galactic Nuclei, AGNs) can help constrain the processes that feed SMBHs and halt star formation in galaxies, but are difficult to obtain for the most luminous AGNs (quasars). We introduce Mean-Field Independent Component Analysis (MFICA) to decompose quasar spectra and obtain recent star formation histories of their host galaxies. Applying MFICA to quasar spectra from the Sloan Digital Sky Survey (SDSS) DR7 Quasar Catalogue in the redshift range $0.16 \leq z \leq 0.76$, we find that 53 per cent of quasar host galaxies are star-forming, 17 per cent lie in the green-valley, while only 5 per cent are quiescent. This contrasts with 14, 11, and 74 per cent of a mass-matched control sample that are star-forming, green-valley, and quiescent, respectively. We find that $\sim25$ per cent of quasars are hosted by post-starburst galaxies, an excess of $28\pm1$ compared to our control sample. While the heterogeneity of recent star formation histories implies multiple SMBH feeding mechanisms, the excess of post-starburst host galaxies demonstrates the link between accreting SMBHs and a recent starburst followed by rapid quenching. Given that massive post-starburst galaxies are predominantly caused by gas-rich major mergers, our results indicate that $30-50$ per cent of quasars originate from merger-induced starbursts.

The planned IceCube-Gen2 radio neutrino detector at the South Pole will enhance the detection of cosmic ultra-high-energy neutrinos. It is crucial to utilize the available time until construction to optimize the detector design. A fully differentiable pipeline, from signal generation to detector response, would allow for the application of gradient descent techniques to explore the parameter space of the detector. In our work, we focus on the aspect of signal generation, and propose a modularized deep learning architecture to generate radio signals from in-ice neutrino interactions conditioned on the shower energy and viewing angle. The model is capable of generating differentiable signals with amplitudes spanning multiple orders of magnitude, as well as consistently producing signals corresponding to the same underlying event for different viewing angles. The modularized approach ensures physical consistency of the samples and leads to advantageous computational properties when using the model as part of a bigger optimization pipeline.

Jets from accreting black hole (BH) X-ray binaries (XRBs) are powerful outflows that release a large fraction of the accretion energy to the surrounding environment, providing a feedback mechanism that may alter the interstellar medium (ISM) properties. Studying accretion and feedback together enables estimates of matter and energy input/output around accreting BHs. We focus on the extended jet structures of the BH-XRB GRS1758-258. First seen in VLA data, these parsec-scale jets arise from jet-ISM interaction and show a Z-shaped morphology. Using the MeerKAT telescope we observed GRS1758-258 in L-band for a total exposure of 7 hr. Applying a calorimetry-based method developed for AGN and later used for XRBs, we estimated the properties of the jets and of the surrounding ISM. We detect a jet and counter-jet terminating in bow-shocks. Within the northern jet lobe we identify synchrotron and bremsstrahlung emission, while the southern lobe is dominated by thermal emission. We measure ISM densities between 10-40 cm-3 across both jets, slightly lower in the northern region. The estimated ages of the two lobes range from 6-51 kyr. The time-averaged jet power lies between 4.4x10^33 and 3.3x10^36 erg/s, with differences between north and south likely due to different local ISM conditions. Comparing new MeerKAT with archival VLA data, we measured a proper motion of 130 mas/yr in a portion of the northern jet. Jet-ISM interaction structures on both sides of GRS1758-258 reveal different ISM properties. The comparison between these structures and those from other XRBs suggests that the lobes in GRS1758-258 are younger and may result from different jet activity phases. The time-averaged energy transferred to the environment is slightly lower than in other XRBs, consistent with the younger age of the lobes in GRS1758-258 relative to those of other systems.

There is a long-standing discussion in the astrophysical/astrochemical community as to the structure and morphology of dust grains in various astrophysical environments (e.g., interstellar clouds, protostellar envelopes, protoplanetary and debris disks, and the atmospheres of exoplanets). Typical grain models assume a compact dust core which becomes covered in a thick ice mantle in cold dense environments. In contrast, less compact cores are likely to exhibit porosity, leading to a pronounced increase in surface area with concomitant much thinner ice films and higher accessibility to the bare grain surface. Several laboratory experimental and theoretical studies have shown that this type of dust structure can have a marked effect on several physico-chemical processes, including adsorption, desorption, mobility, and reactivity of chemical species. Porous grains are thus thought to likely play a particularly important and wide-ranging astrochemical role. Herein, we clarify what is meant by porosity in relation to grains and grain agglomerates, assess the likely astrochemical effects of porosity and ask whether a fractal/porous structural/morphological description of dust grains is appropriate from an astronomical perspective. We provide evidence for high porosity from laboratory experiments and computational simulations of grains and their growth in various astrophysical environments. Finally, we assess the observational constraints and perspectives on cosmic dust porosity. Overall, our paper discusses the effects of including porosity in dust models and the need to use such models for future astrophysical, astrochemical and astrobiological studies involving surface or solid-state processes.

Because they are likely to accrete substantial amounts of interstellar gas, merging supermassive binary black holes are expected to be strong multimessenger sources, radiating gravitational waves, photons from thermal gas, and photons from relativistic electrons energized by relativistic jets. Here we report on a numerical simulation that covers the late inspiral, merger, and initial postmerger phase of such a system where both black holes have the same mass and spin, and both spin axes are parallel to the orbital angular momentum. The simulation incorporates both 3D general relativistic magnetohydrodynamics and numerical relativity. The thermal photon power during the late inspiral, merger, and immediate postmerger phases is drawn from strong shocks rather than dissipation of turbulence inside a smoothly structured accretion disk as typically found around accreting single black holes. We find that the thermal photon and jet Poynting flux outputs are closely related in time, and we posit a mechanism that enforces this relation. The power radiated in both photons and jets diminishes gradually as merger is approached, but jumps sharply at merger to a noisy plateau. Such a distinct lightcurve should aid efforts to identify supermassive black hole mergers, with or without accompanying gravitational wave detections.

The physical processes behind astrophysical collisionless shocks, such as thermal relaxation and ionization after shock passage, remain poorly understood. To investigate these processes, we analyze the northeastern region of the Cygnus Loop with XMM-Newton. The electron temperature is found to increase towards the interior of the remnant ranging from 0.15-0.19 keV energy range within a spatial scale of 6 arcmin (or 1.27 pc at a distance of 725 pc) from the shock front. This can be explained well by a modified Sedov solution with radiative cooling. We also show that the ionization timescales determined from our spectroscopy are significantly larger than those estimated based on the electron density of the surrounding materials and the shock velocity. This excess can be qualitatively explained by a mixing of inner multiple plasma components with different ionization states due to turbulence.

An extremely energetic muon has been recently detected by the Cubic Kilometre Neutrino Telescope (KM3NeT), indicating the observation of a neutrino with the estimated energy of $\left( 2.2^{+5.7}_{-1.0} \right)\times 10^{17}$~eV. Radio blazar PMN~J0606$-$0724, not detected in gamma rays, is located within the reported error region of the neutrino arrival direction, and was flaring at the time of the event. Here we demonstrate that the neutrino could be produced in a photohadronic interaction in its radio core. The necessary proton power is of order of the source's photon luminosity, and protons can be accelerated to the required energies in the core, while high-energy gamma rays cannot leave the source because of intense production of electron-positron pairs. Expected contribution of the population of similar flaring sources matches non-observation of energetic events by other neutrino telescopes.

The periodic solution of the Friedmann equation in conformal time, implies that only cosmological perturbations exhibiting corresponding symmetries are physically permissible, leading to a discrete spectrum of allowed wave vectors. Furthermore, in a spatially closed universe, these wave vectors are independently constrained to be integers. Matching these two distinct quantization conditions provides a novel theoretical constraint on the possible values of spatial curvature. In this work, we numerically solve the cosmological perturbation equations, incorporating radiation anisotropy and higher-order Boltzmann terms, to calculate these discrete wave vectors with improved precision. Subsequently, we generate Cosmic Microwave Background (CMB) power spectra for different characteristic spacings of these quantized wave vectors. Finally, we apply the constraint to Planck 2018 observational data to determine the cosmological parameters. This analysis yields a discrete set of allowed values for the spatial curvature, $\Omega_K$, including $[-0.076,-0.039, -0.024, -0.016, -0.012, \dots]$.

As the compact binary catalog continues to grow rapidly, developing and refining tests to probe the nature of compact objects is essential for a comprehensive understanding of both the observed data and the underlying astrophysics of the binary population. We investigate the effectiveness of spin-induced multipole moments (SIQM) and tidal deformability measurements in distinguishing lower mass-gap black hole (BH) binaries from non-BH binaries with different mass and spin configurations. We perform model-agnostic tests on binary BH (BBH) simulations using full Bayesian inference, evaluating the independent and joint measurability of SIQM and tidal parameters across the parameter space. We extend the analysis to simulations of self-interacting spinning boson stars, using synthetic signals that exhibit (a) both SIQM and tidal effects and (b) each effect individually. For case (a), recovery is performed using (i) a BBH model, (ii) a model incorporating both SIQM and tidal effects, and (iii) models including either SIQM or tidal effects. For case (b), we employ (i) a BBH model and (ii) models incorporating either SIQM or tidal effects, consistent with the injection. Simulations employ TaylorF2 waveform model and consider binaries in the low mass gap with varying spin magnitudes. We find that employing an incorrect model to analyze the signal can lead to biases in parameter inference. Notably, when analyzing a simulated binary boson star-like signal with component masses $\rm{(4, 4) \, M_{\odot}}$ using a BBH model, the system is incorrectly identified as having masses $\rm{(8, 2) \, M_{\odot}}$. In contrast, using the correct recovery model that includes both SIQM and tidal deformability effects successfully recovers the true masses, highlighting the significance of waveform model accuracy in performing reliable distinguishability tests for compact objects in the low-mass gap.

In this paper, we investigate the critical collapse leading to primordial black hole (PBH) formation in a universe dominated by a self-interacting scalar field with a quartic potential, comparing it to the well-known radiation-dominated case. Using fully relativistic nonlinear numerical simulations in spherical symmetry, based on the Misner--Sharp formalism, we analyze the dynamics near the collapse threshold and track the scaling of the black hole mass. Our results confirm that both the scalar field and radiation cases exhibit type II critical behavior with similar -- though not identical -- critical exponents, differing by about $2\sigma$. This suggests that, while a quartic scalar field effectively mimics a radiation fluid even in the nonlinear collapse regime, small differences in the critical exponent persist. Our findings provide direct numerical evidence for the near universality of the critical exponent in PBH formation, with only mild dependence on whether the collapse is driven by a scalar field or a perfect fluid.

We performed counts of stars with poor astrometric solutions of Gaia DR3 in the regions of open star clusters: NGC 188, NGC 1039, NGC 2287, NGC 2301, NGC 2360, NGC 2420, NGC 2527, NGC 2548, NGC 2682 (M 67), NGC 3114, NGC 3766, NGC 5460, NGC 6649. The selection of the possible cluster members is based on the Gaia photometry using the Hess diagram. We look for stars that fall within the region of the Hess diagram plotted from probable cluster members based on Hunt & Reffert data. We take stars with two-parameter solutions, with the parameter RUWE>1.4, as well as with large relative parallax errors that fall within the Hess diagram region for probable cluster members. The radii of clusters based on stars with poor astrometric solutions and the number of such possible cluster members were estimated. The number of stars with poor astrometric solutions relative to the number of stars from the Hunt & Reffert sample N_bad/N varies very widely with a median average of approximately 30%. This means that when one selects probable cluster members based on precise astrometric data from Gaia DR3, an average of about 23% of cluster members may be lost. Among the lost stars there may be a significant number of unresolved binary and multiple systems. We investigated the dependence of the relative number of stars with poor astrometric solutions on the galactic latitude and on the average number density of stars. The brightness functions with and without stars with poor solutions differ significantly in the region of faint stars 14<G<18 mag for clusters with a relative number of possible cluster members with poor astrometric solutions of N_bad/N>=0.15.

Polarimetric data provide key insights into infrared emission mechanisms in the inner disks of YSOs and the details of dust formation around AGB stars. While polarization measurements are well-established in radio interferometry, they remain challenging at visible and near-infrared due to the significant time-variable birefringence introduced by the complex optical beamtrain. In this study, we characterize instrumental polarization effects within the optical path of the CHARA Array, focusing on the H-band MIRC-X and K-band MYSTIC beam combiners. Using Jones matrix formalism, we developed a comprehensive model describing diattenuation and retardance across the array. By applying this model to an unpolarized calibrator, we derived the instrumental parameters for both MIRC-X and MYSTIC. Our results show differential diattenuation consistent with >= 97% reflectivity per aluminum-coated surface at 45 deg incidence. The differential retardance exhibits small wavelength-dependent variations, in some cases larger than we expected. Notably, telescope W2 exhibits a significantly larger phase shift in the Coude path, attributable to a fixed aluminum mirror (M4) used in place of deformable mirrors present on the other telescopes during the observing run. We also identify misalignments in the LiNbO_3 birefringent compensator plates on S1 (MIRC-X) and W2 (MYSTIC). After correcting for night-to-night offsets, we achieve calibration accuracies of $\pm$ 3.4% in visibility ratio and $\pm$ 1.4 deg in differential phase for MIRC-X, and $\pm$ 5.9% and $\pm$ 2.4 deg, respectively, for MYSTIC. Given that the differential intrinsic polarization of spatially resolved sources, such as AGB stars and YSOs, typically greater than these instrumental uncertainties, our results demonstrate that CHARA is now capable of achieving high-accuracy measurements of intrinsic polarization in astrophysical targets.

We study the dynamics of a two-field scalar model consisting of an axion-saxion pair with both kinetic and potential couplings, as motivated by string theory compactifications. We extend the dynamical systems (DS) toolkit by introducing a new set of variables that not only close the system and enable a systematic stability analysis, but also disentangle the role of the kinetic coupling. Within this framework we derive a compact, general expression for the non-geodesicity (turning-rate) parameter evaluated at fixed points, valid for arbitrary couplings. This provides a transparent way of diagnosing non-geodesic dynamics, with direct applications to both dark energy and multifield inflation. We first consider exponential coupling functions to establish analytic control and facilitate comparison with previous literature. In this case, we uncover a pair of genuinely non-geodesic fixed points, which act as attractors within a submanifold of the full system. In contrast, when the axion shift symmetry remains unbroken, our analysis shows that the apparent non-geodesic fixed point reported previously does not persist once the full dynamics are taken into account. Finally, we illustrate how our approach naturally extends to more realistic string-inspired models, such as power-law axion potentials combined with exponential saxion couplings, and present an explicit supergravity realisation.

We study the matter power spectrum constraint on primordial black holes (PBH) by the dark matter (DM) emitted through Hawking radiation. We particularly focus on the scenario where PBH, with mass ranges between 1g and $10^9$g, evaporates before big-bang nucleosynthesis (BBN). Addition to that, we consider the case where PBH abundance is scarce and there is no early PBH domination taking place. On the DM side, we assume a fraction of the population is produced from PBH evaporation, while the remaining part is the regular cold dark matters (CDMs) which is produced by some genesis processes that decouples later on. Therefore, in the rest of the cosmological history, DM interacts solely through gravity. Under this condition, there is no thermal equilibrium ever established between DM and SM plasma. An important feature in our analysis is that, for the light PBH we consider, its temperature is much larger than the mass of DM which is consequently produced ultra-relativistically and require a protracted time to become matter-like. In this context, even though PBH evaporates in the very early Universe, PBH-produced DM could still be energetic and smooth out the small scale structure at much later time. By the precision measurement on the matter power spectrum from cosmic surveys, we are able to set joint constraint on light PBHs and the non-cold DMs it produced.

The $^{93}$Nb($t$,$^{3}$He) reaction at 115 MeV/u was studied to demonstrate that nuclear level densities and $\gamma$-ray strength functions can be extracted from charge-exchange reactions at intermediate energies using the Oslo technique. The matrix of excitation energy in $^{93}$Zr, reconstructed from the ($t$,$^{3}$He) reaction, versus the energy of $\gamma$ rays emitted by the excited $^{93}$Zr nuclei, was obtained in an experiment with the S800 Spectrograph operated in coincidence with the GRETINA $\gamma$-ray detector. The extracted level density and $\gamma$-ray strength function obtained by applying the Oslo method to this matrix were used to estimate the $^{92}$Zr($n$,$\gamma$)$^{93}$Zr cross section by combining the new results with other experimental data and theoretical calculations for $E$1 and $M$1 strength functions at higher energies. Good agreement with direct measurements of the $^{92}$Zr($n$,$\gamma$)$^{93}$Zr cross section was found. The contribution from the upbend in the extracted $\gamma$-ray strength function was important to achieve the consistency as the neutron-capture cross section without this contribution is significantly below the direct measurements otherwise. Since charge-exchange reactions at intermediate energies have long been used for extracting Gamow-Teller strengths, the successful demonstration of the charge-exchange Oslo method enables experiments in which ($n$,$\gamma$) cross sections and Gamow-Teller strengths can be measured simultaneously, which is of benefit for astrophysical studies.

In the 1970s, the renowned physicist Victor Weisskopf famously developed a research program to qualitatively explain properties of matter in terms of the fundamental constants of physics. But there was one type of matter prominently missing from Weisskopf's analysis: life. Here, we develop Weisskopf-style arguments demonstrating how the fundamental constants of physics can be used to understand the properties of living systems. By combining biophysical arguments and dimensional analysis, we show that vital properties of chemical self-replicators, such as growth yield, minimum doubling time, and minimum power consumption in dormancy, can be quantitatively estimated using fundamental physical constants. The calculations highlight how the laws of physics constrain chemistry-based life on Earth, and if it exists, elsewhere in our universe.

The low-level RF (LLRF) systems for linear accelerating structures are typically based on heterodyne architectures. The linear accelerators normally have many RF stations and multiple RF inputs and outputs for each station, so the complexity and size of the LLRF system grows rapidly when scaling up. To meet the design goals of being compact and affordable for future accelerators, or upgrading existing ones, we have developed and characterized the next generation LLRF (NG-LLRF) platform based on the RF system-on-chip (RFSoC) for S-band and C-band accelerating structures. The integrated RF data converters in RFSoC sample and generate the RF signals directly without any analogue mixing circuits, which significantly simplified the architecture compared with the conventional LLRF systems. We have performed high-power tests for the NG-LLRF with the S-band accelerating structure in the Next Linear Collider Test Accelerator (NLCTA) test facility at SLAC National Accelerator Laboratory and a C-band structure prototyped for Cool Cooper Collider (CCC). The NG-LLRF platform demonstrated pulse-to-pulse fluctuation levels considerably better than the requirements of the targeted applications and high precision and flexibility in generating and measuring the RF pulses. In this paper, the characterization results of the platform with different system architectures will be summarized and a selection of high-power test results of the NG-LLRF will be presented and analyzed.

Accurate and reliable solar flare predictions are essential to mitigate potential impacts on critical infrastructure. However, the current performance of solar flare forecasting is insufficient. In this study, we address the task of predicting the class of the largest solar flare expected to occur within the next 72 hours. Existing methods often fail to adequately address the severe class imbalance across flare classes. To address this issue, we propose a solar flare prediction model based on multiple deep state space models. In addition, we introduce the frequency & local-boundary-aware reliability loss (FLARE loss) to improve predictive performance and reliability under class imbalance. Experiments were conducted on a multi-wavelength solar image dataset covering a full 11-year solar activity cycle. As a result, our method outperformed baseline approaches in terms of both the Gandin-Murphy-Gerrity score and the true skill statistic, which are standard metrics in terms of the performance and reliability.

The future space-based gravitational wave observatory LISA is expected to detect massive black hole binaries (MBHBs) with high signal-to-noise ratios (SNRs), ranging up to thousands. Such high-precision observations require accurate modeling of the detector response. However, current derivations of the response function neglect the motion of the spacecraft during light travel time, omitting velocity-dependent terms of order $\beta = v/c \sim 10^{-4}$. In this work, we derive the velocity-dependent corrections to the gravitational wave response. We analyze the contribution of the velocity-terms for MBHBs in the mass range $[10^6,10^8]\:\mathrm{M}_{\odot}$ using a modified version of the state-of-the-art response simulator lisagwresponse. We find that corrections introduce residual SNRs up to $\sim 2$ for the loudest events and fractional differences up to $0.04\%$, compared to lisagwresponse. While small, these effects are comparable to current waveform modeling uncertainties and imprint distinctive sky-localization signatures, making them potentially relevant for parameter estimation of high-mass MBHBs and simulation of mock datasets.

Anisotropic phases potentially play a role in the internal composition of neutron stars, the main laboratory for the phase structure of QCD at high baryon densities. We review the study of such a phase, the chiral density wave, within a phenomenological nucleon-meson model, including nucleonic vacuum fluctuations within a renormalization scheme recently developed. Neutron stars in this model and within our approximations either do not contain a chiral density wave core or they are too light to agree with observations.

The effective nucleon mass (M^*) plays a central role in Quantum Hadrodynamics-I (QHD-I), linking scalar meson interactions at the microscopic level to the macroscopic properties of dense nuclear matter. In this work, we re-derive the scalar density integral in detail and validate it numerically using Gaussian quadrature. The numerical and analytic results are found to be in excellent agreement, confirming the robustness of both approaches. We then investigate the sensitivity of M^* to different parameter sets, highlighting its strong influence on nuclear saturation, compressibility, and the resulting equation of state (EoS). The analysis shows that variations in meson-nucleon couplings propagate directly into differences in pressure and energy density, affecting the stiffness of the EoS. While QHD-I produces characteristically stiff EoS, the effective mass evaluation provides a transparent framework for connecting microscopic meson dynamics to macroscopic neutron star properties. These findings underline the relevance of M^* as a microscopic-macroscopic bridge and demonstrate the utility of numerical methods for extending relativistic mean-field models in nuclear astrophysics.

It is shown how the optimal detector of Gaussian signals can be represented in terms of Bertrand's class of time-frequency distributions. In this representation, the detector is a correlation between the corresponding time-frequency distributions. Since Bertrand's class is related to the power-law chirp signals, the new representation can be useful for their detection. The new approach is shown to be more effective then other time-frequency methods for the case of phase-insensitive detection. The finding provides a complementary representation to Cohen's class representation in the time-frequency domain already known in the literature.

Ten years ago humankind achieved the first direct observation of gravitational waves. I give some personal recollections of that first detection. I also present an incomplete summary of what we have learned since then, and some speculations on what we may learn in the future.

The fermionic nature of neutrinos and the origin of their tiny masses remain unresolved issues in particle physics, intrinsically connected to lepton number symmetry-conserved for Dirac, violated for Majorana, and effectively pseudo-Dirac when global symmetries invoked for conservation are broken by quantum gravity. We investigate whether distinctive gravitational-wave (GW) signatures can illuminate the nature of neutrino masses and their underlying symmetries, particularly in scenarios where Yukawa couplings are not unnaturally small. To this end, we consider the minimal $B-L$ gauge extension of the Standard Model, where quantum numbers of beyond-SM states determine the neutrino nature and the scale of spontaneous $B-L$ breaking governs mass generation. In this framework, we show that neutrinos yield characteristic GW spectra: Majorana neutrinos with high-scale breaking ($\sim 10^{14}$ GeV) produce local cosmic strings and a flat spectrum across broad frequencies, Dirac neutrinos with low-scale breaking ($\sim 10^{7}$ GeV) generate peaked spectra from first-order phase transitions, and pseudo-Dirac scenarios give kink-like features from domain wall annihilation.