Papers for Tuesday, Nov 11 2025

AstroPix is a high-voltage CMOS (HV-CMOS) monolithic active pixel sensor originally developed to enable precision gamma-ray imaging and spectroscopy in the medium-energy regime (approximately 100 keV-100 MeV) based on the groundwork laid by ATLASpix and MuPix. It features a 500 um pixel pitch, in-pixel amplification and digitization, and low power consumption (around 3-4 mW/cm^2), making it scalable for large-area, multilayer telescope detector planes. The detectors have a designed dynamic range of 25 keV to 700 keV. With these features, AstroPix meets the requirements of future space-based high-energy telescopes and the imaging layers of the Barrel Imaging Calorimeter (BIC) in the Electron-Proton/Ion Collider (ePIC) detector at the future Electron-Ion Collider (EIC). For the space-based payload, AstroPix is being integrated into sounding rocket and balloon payloads to demonstrate the technical readiness of the devices. For BIC, AstroPix-based imaging layers interleaved within the lead/scintillating-fiber (Pb/SciFi) sampling calorimeter provide granular shower imaging, enabling key performance features such as electron/pion or gamma/neutral-pion separation. As part of the ongoing detector R&D efforts, we have been testing various AstroPix v3 configurations: the single chip, a quad-chip assembly, a three-layer stack of quad chips, and a nine-chip module that represents the smallest prototype unit of the BIC imaging layer. This presentation will highlight recent performance test results from these AstroPix detector configurations.

Observing the circumgalactic medium (CGM) in emission lines from ionized gas enables direct mapping of its spatial and kinematic structure, offering new insight into the gas flows that regulate galaxy evolution. Using the high-resolution Figuring Out Gas & Galaxies In Enzo (FOGGIE) simulations, we generate mock emission-line maps for six Milky Way-mass halos. Different ions (e.g., HI, OVI) trace distinct CGM phases and structures, highlighting the importance of observations in multiple species. We quantify the observable CGM mass fraction as a function of instrument spatial resolution and surface brightness sensitivity, finding that sensitivity is the dominant factor limiting detectability across all ions. At fixed sensitivity, higher spatial resolution reveals more structures; at fixed spatial resolution, higher sensitivity recovers a higher percentage of the total mass. We explore CGM kinematics by constructing emissivity-weighted projected velocity maps and comparing line-of-sight velocities between ions. OVI shows the largest kinematic deviation from HI, while MgII and SiII most closely follow HI velocities. Distinguishing these phases out to 50kpc from the galaxy center requires spectral resolution better than 30km/s for most ion pairs. Additionally, separating inflowing from outflowing gas based on projected kinematics also requires high spectral resolution: at 30km/s, more than 80% of gas above the emission detection threshold can be distinguished kinematically, but this fraction drops to <40% with a resolution of 200km/s. Our results provide predictions for future UV and optical instruments, showing that recovering the multiphase structure and kinematics of circumgalactic emission will require both high sensitivity and fine kinematic resolution.

The progenitors of present-day galaxy clusters offer crucial insight into how galaxies and large-scale structure co-evolve in the early Universe. We present JWST/NIRCam grism spectroscopy of the photometrically identified $z=7.66$ protocluster core in the SMACS J0723.3-7327 lensing field, SMACS-PC-z7p7. Six [O III]-emitters and five additional photometric candidates are found within a 0.3 arcmin$^2$ ($1.5\ {\rm cMpc}^2$) region, corresponding to an overdensity of $\delta \sim 200$. Despite the extreme overdensity, the resident galaxies exhibit star-formation histories, UV-slopes and neutral hydrogen column densities that are consistent with those of field galaxies at similar redshifts. This is in stark contrast with the consistently high neutral hydrogen column densities, old stellar populations and large dust masses of galaxies within a $z=7.88$ protocluster in the Abell 2744 field. Comparison with the TNG-Cluster and TNG300 simulations indicates a halo mass of ${\rm log_{10}}(M_{200{\rm c}}[{\rm M_{\odot}}]) = 11.4\pm0.2$, and implies that, on average, SMACS-PC-z7p7 will evolve into a present-day Fornax-like cluster (${\rm log_{10}}(M_{200{\rm c},\ z=0}[{\rm M_{\odot}}]) = 13.7\pm0.6$). The uniformly young, highly star-forming nature of the galaxy population of SMACS-PC-z7p7 suggests that environmental effects only become significant above halo masses of ${\rm log_{10}}(M_{200{\rm c}}[{\rm M_{\odot}}]) \gtrsim 11.5$. Comparison to other $z\gtrsim7$ protoclusters reveals that vigorous star formation persists in lower-mass protoclusters, whereas accelerated evolution and suppression of star formation emerge in more massive haloes. SMACS-PC-z7p7 therefore represents an early stage of protocluster assembly, where residence within an overdense environment still enhances star formation, and feedback processes have yet to exert a significant influence.

Since the launch of JWST, observations of exoplanetary atmospheres have seen a revolution in data quality. Given that atmospheric parameter inferences depend heavily on the underlying data, a re-evaluation of current methodologies is warranted to assess the reliability of these results. We investigate the impact of variations in input spectra on atmospheric retrievals for the hot Jupiter WASP-39 b using JWST transit data. Specifically, we analyse the reliability of parameter estimations from random perturbations of the underlying spectrum and their sensitivity to three transmission spectra derived from the same observational data. Using the NIRSpec PRISM observation from a single transit of WASP-39 b, we perform retrievals with the TauREx framework. As a baseline, we use a spectrum derived with the Eureka! data reduction pipeline. To evaluate retrieval reliability, we analyse posterior distributions under deviations from this spectrum. We simulate random noise by performing retrievals on scattered instances of this spectrum and compare them with retrievals based on existing spectra reduced from the same raw observation. Our analysis identifies three types of posterior distributions: (1) Stable, Gaussian distributions for species constrained across the entire spectrum (e.g., H2O, CO2); (2) Uniform posteriors with upper bounds for weakly constrained species (e.g., CO, CH4); and (3) Unstable, heavy-tailed posteriors for species constrained by minor spectrum features (e.g., SO2, C2H2). We find that other parameters, such as the planetary radius and p-T profile, are stable under spectral perturbations. Posterior distributions differ for retrievals on independently reduced transmission spectra from the same raw data, complicating interpretation, particularly for skewed distributions. Based on this, we advocate for careful assessment and selection of credible interval sizes to reflect this.

The accelerated expansion of the Universe is well established by geometric probes, yet its physical origin remains poorly understood. Most constraints on dark energy arise from background observables -- supernovae, baryon acoustic oscillations, and the cosmic microwave background -- which mainly test the homogeneous expansion history. To move beyond this limitation, we examine how kinetic Sunyaev--Zel'dovich (kSZ) tomography, combined with galaxy clustering, can probe perturbative effects of dark energy and improve constraints on its background parameters. Using a Fisher-matrix analysis of the joint power spectra for LSST- and CMB-S4-like surveys, we quantify the additional information kSZ tomography contributes to dark-energy inference. Including kSZ data tightens constraints on $w_0$ by 15 % and on $w_a$ by 32 %, with parameter degeneracies distinct from those of geometric probes. We also assess the detectability of dark-energy perturbations through a two-parameter model, finding that for canonical sound speed ($c_s=1$) the effects are sub-percent and confined to horizon scales, while smaller sound speeds shift them to accessible $k$-ranges. Near-term kSZ measurements will primarily serve to test the consistency between background and perturbative signals, while future low-noise, high-resolution surveys may begin to uncover the microphysical properties of dark energy.

The complex task of unraveling the assembly history of the Milky Way is in constant evolution with new substructures identified continuously. To properly validate and characterise the family of galactic progenitors, it is important to take into account all the effects that can shape the distribution of tracers in the Galaxy. First among the often overlooked actors of galactic dynamics is the rotating bar of the Milky Way that can affect orbital tracers in multiple ways. We want to fully characterise the effect of the rotating bar of the Milky Way on the distribution of galactic tracers, provide diagnostics helpful in identifying its effect and explore the implications for the search and identification of substructures. We use the in-house Orbital Integration Tool (OrbIT), built to include the full effect of the bar and exploit its multidimensional output to perform a complete dynamical characterisation of a large sample of carefully selected Milky Way stars with very precise astrometry. We identify conspicuous overdensities in several orbital parameter spaces and verify that they are caused by the bar-induced resonances. We also show how contamination by trapped tracers provides local density enhancements that mimic the clumping usually attributed to genuine substructures. We provide a new and expedite way of identifying resonant loci and, consequently, to estimate the contribution of stars trapped into orbital resonances to phase-space overdensities previously identified as candidate relics of past merging events. Among those analysed here, we found that the detections of Cluster 3 and Shakti seem to have gained a non-negligible boost from resonance-trapped stars. Nyx is the most extreme case, with 70% of assigned member stars lying on resonant orbit, strongly suggesting that it is not the genuine relic of a merger event but an overdensity caused by bar-induced resonances

$\eta_{\oplus}$, the occurrence rate of rocky habitable zone exoplanets orbiting Sun-like stars, is of great interest to both the astronomical community and the general public. The Kepler space telescope has made it possible to estimate $\eta_{\oplus}$, but estimates by different groups vary by more than an order of magnitude. We identify several causes for this range of estimates. We first review why, despite being designed to estimate $\eta_{\oplus}$, Kepler's observations are not sufficient for a high-confidence estimate, due to Kepler's detection limit coinciding with the $\eta_{\oplus}$ regime. This results in a need to infer $\eta_{\oplus}$, for example extrapolating from a regime of non-habitable zone, non-rocky exoplanets. We examine two broad classes of causes that can account for the large discrepancy in $\eta_\oplus$ found in the literature: a) differences in definitions and input data between studies, and b) fundamental limits in Kepler data that lead to large uncertainties and poor accuracy. We highlight the risk of large biases when using extrapolation to describe small exoplanet populations in the habitable zone. We discuss how $\eta_{\oplus}$ estimates based on Kepler data can be improved, such as reprocessing Kepler data for more complete, higher-reliability detections and better exoplanet catalog characterization. We briefly survey upcoming space telescopes capable of measuring $\eta_{\oplus}$, and how they can be used to supplement Kepler data.

Searching for life elsewhere in the universe is one of the most highly prioritized pursuits in astronomy today. However, the ability to observe evidence of Earth-like life through biosignatures is limited by the number of planets in the solar neighborhood with conditions similar to Earth. The occurrence rate of Earth-like planets in the habitable zones of Sun-like stars, $\eta_{\oplus}$, is therefore crucial for addressing the apparent lack of consensus on its value in the literature. Here we present a review of the current understanding of $\eta_{\oplus}$. We first provide definitions for parameters that contribute to $\eta_{\oplus}$. Then, we discuss the previous and current estimated parameter values and the context of the limitations on the analyses that produced these estimates. We compile an extensive list of the factors that go into any calculation of $\eta_{\oplus}$, and how detection techniques and surveys differ in their sensitivity and ability to accurately constrain $\eta_{\oplus}$. Understanding and refining the value of $\eta_{\oplus}$ is crucial for upcoming missions and telescopes, such as the planned Habitable Worlds Observatory and the Large Interferometer for Exoplanets, which aim to search for biosignatures on exoplanets in the solar neighborhood.

We report a survey of molecular emission from cometary volatiles using the Atacama Large Millimeter/Submillimeter Array (ALMA) toward comet C/2017 K2 (PanSTARRS) carried out on UT 2022 September 21, 22, and 23 at a heliocentric distance (\rh{}) of 2.1 au. These measurements of HCN, CS, CO, CH$_3$OH, and H$_2$CO (along with continuum emission from dust) sampled molecular chemistry in C/2017 K2 at the inner edge of the H$_2$O sublimation zone, discerning parent from daughter or extended source species. This work presents spectrally integrated flux maps, production rates, and parent scale lengths for each molecule. CH$_3$OH, CO, and HCN were produced within $\sim$250 km of the nucleus, potentially including contributions from sublimation of icy grains. CS was consistent with production from CS$_2$ photolysis, and H$_2$CO required production from extended sources in the coma. An ortho-to-para ratio OPR=$2.9\pm0.4$ for H$_2$CO was derived from simultaneously measured transitions of each spin species. The continuum was extended and spatially resolved, consistent with thermal emission from dust in the coma. Analysis of the continuum visibilities provided an upper limit on the nucleus diameter $d<6.6$ km and coma dust masses of $1.2-2.4\times10^{11}$ kg.

Continuum reverberation mapping probes the size scale of the optical continuum-emitting region in active galactic nuclei (AGN). The source of this emission has long been thought to originate from the accretion disk, but recent studies suggest the broad line region (BLR) may significantly contribute to both the observed flux and continuum interband delays. We monitored 18 AGN over four years of observations to acquire high quality optical continuum light curves, measuring time lags between different photometric bands and determining continuum emission sizes for each AGN. We add this sample to existing lag measurements to test the correlation between continuum lags at $5100Å$ ($\tau_{5100}$) and $5100Å$ luminosity ($L_{5100}$). We observe that $\tau_{5100} \propto L_{5100}^{0.4}$, broadly consistent with the theoretical expectations of $\tau \propto L^{1/2}$ expected for continuum reverberation from either the accretion disk or the BLR.

We propose a predictive $SO(10)$ Grand Unified Theory (GUT) framework for cosmic inflation in the Palatini $\mathcal{R}^2$ formulation of gravity. In this model, a GUT Higgs field both drives inflation and induces intermediate-scale symmetry breaking, thereby linking primordial cosmology, gauge unification, and topological defect formation. A partial inflationary phase of $N_I \sim 10$--$17$ $e$-folds following monopole formation can dilute magnetic monopoles to abundances $Y_M \sim 10^{-35}$--$10^{-27}$. The model yields Cosmic Microwave Background (CMB) predictions of $0.955 \lesssim n_s \lesssim 0.974$, accommodating the tensions between Planck-BICEP ($n_s \approx 0.965$) and Planck+ACT ($n_s \approx 0.971$) via $\phi < M$ and $\phi > M$ branches repectively. The predicted tensor-to-scalar ratio $r \lesssim 8\times10^{-4}$ lies within current observational constraints and is accessible to forthcoming experiments, including the Simons Observatory and LiteBIRD. The resulting correlations between the unification scale $M_U$, the inflationary observables $(n_s, r)$, and proton-decay lifetimes highlight a complementarity between CMB measurements and proton-decay searches, with regions of parameter space testable in forthcoming experiments such as Hyper-Kamiokande and DUNE.

With the implementation of a low-energy trigger, the surface array of the IceCube Neutrino Observatory is able to record cosmic-ray induced air showers with a primary energy of a few hundred TeV. This extension of the energy range closes the gap between direct and indirect observations of primary cosmic rays and provides the potential to test the validity of hadronic interaction models in the sub-PeV regime. Composition analyses at IceCube highly benefit from its multi-detector design. Combining the measurement of the electromagnetic shower component and low-energy muons at the surface with the response of the in-ice array to the associated high-energy muons improves the directional reconstruction accuracy and opens unique possibilities to extract the primary particle's mass. In this contribution, a new methodical approach for the analysis of these low-energy air showers is presented, including techniques for the identification of coincident background in the in-ice detector and a machine learning model based on convolutional neural networks to determine the elemental composition. The achieved performance in primary mass discrimination and energy reconstruction of air-shower events is discussed.

The chemical abundances of stars in galaxies are a fossil record of the star formation and stellar evolution processes that regulate galaxy formation, including the stellar initial mass function, the fraction and timing of type Ia supernovae (SNeIa), and nucleosynthesis inside massive stars. In this paper, we systematically explore uncertainties associated with modeling chemical enrichment in dwarf galaxies. We repeatedly simulate a single EDGE-INFERNO dwarf ($M_{\star} \approx 10^5 \, M_{\odot}$), varying the chemical yields of massive stars, the timing and yields of SNeIa, and the intrinsic stochasticity that arises from sampling individual stars and galaxy formation chaoticity. All simulations are high-resolution (3.6 pc), cosmological zoom-in hydrodynamical simulations that track the stellar evolution of all individual stars with masses $>0.5\,{\rm M}_{\odot}$. We find that variations in SNIa assumptions make the largest difference in mean abundance ratios and [Fe/H], highlighting the importance of detailed SNIa modeling even in such low-mass reionization-limited galaxies. In contrast, different massive star yields, accounting (or not) for stellar rotation, result in mean abundances comparable to those arising from stochasticity. Nonetheless, they significantly affect the shape of abundance trends with [Fe/H], for example, through the existence (or not) of a bimodality in the [X/Fe] - [Fe/H] planes, particularly in [Al/Fe]. Finally, we find that the variance arising from random sampling severely limits the interpretation of single galaxies. Our analysis showcases the power of star-by-star cosmological models to unpick how both systematic uncertainties (e.g., assumptions in low-metallicity chemical enrichment) and statistical uncertainties (e.g., averaging over enough galaxies and stars within a galaxy) affect the interpretation of chemical observables in ultra-faint dwarf galaxies.

Determining whether black hole jets are dominated by leptonic or baryonic matter remains an open question in high-energy astrophysics. We propose that extreme mass ratio binary (EMRB) black holes, where an intermediate mass secondary black hole (a "miniquasar") periodically interacts with the accretion flow of a supermassive black hole (SMBH), offer a natural laboratory to probe jet composition. In an EMRB, the miniquasar jet is launched episodically after each disk-crossing event, triggered by the onset of super-Eddington accretion. The resulting emissions exhibit temporal evolution as the jet interacts with the SMBH accretion disk. Depending on whether the jet is leptonic or hadronic in composition, the radiative signatures differ substantially. Notably, a baryonic jet produces a more pronounced gamma-ray output than a purely leptonic jet. By modeling the evolution of the multifrequency characteristic features, it is suggested that the gamma-ray-to-UV emissions may serve as a diagnostic tool capable of distinguishing between leptonic and baryonic scenarios. The resulting electromagnetic signals, when combined with multi-messenger observations, offer a powerful means to constrain the physical nature of relativistic jets from black holes.

Context: Ground-based telescopes are susceptible to seeing, an atmospheric phenomenon that reduces the resolving power of large observatories to that of a home telescope. Compensating these effects is therefore critical to realizing the potential of upcoming extremely large telescopes, a challenging task that requires precise wavefront control. Ultimately, this precision is limited by one's wavefront sensor (WFS) and its capacity to accurately encode phase and amplitude aberrations. Aims: Our attention is on photon noise-limited wavefront sensing in the high-Strehl regime. In particular, we seek fundamental limits to phase and amplitude estimation in addition to a WFS that saturate these bounds. Methods: Information theory is employed for deriving minimum-achievable residual errors, as stipulated by a metric called the Holevo Cramer-Rao bound. Holevo's bound is closely related to another metric called the quantum Cramer-Rao bound, which has already been applied to phase estimation on nearly-corrected wavefronts. Results: We present a WFS that can perfectly extract and phase shift a telescope's piston mode. We show how this phase can be used to tune the apparatus' sensitivity to phase and amplitude, and provide a closed-form expression for the optimal phase shift. For circular apertures, this implementation saturates the fundamental limits, but it can be easily modified to work with arbitrary pupils. Moreover, our proposal uses optics that are manufactureable today and is readily achromatized with geometric phase shifters.

Inertial modes have been recently detected in the Sun via helioseismology, yet their origin, evolution, and role in the dynamics of the solar plasma and magnetic field remain poorly understood. In this study, we employ global numerical simulations to investigate the excitation mechanisms and dynamical consequences of inertial modes in the Sun and stellar interiors. We validate first our numerical setup by analyzing the evolution of sectoral and tesseral perturbations imposed on a rigidly rotating sphere. The results confirm that a perturbation of a given mode can excite neighboring modes with both smaller and larger wavenumbers along the dispersion relation of Rossby waves. Subsequently, we use a physically motivated forcing to impose differential rotation with varying shear amplitudes, and examine the spontaneous onset and nonlinear evolution of inertial modes. The simulations reveal that the growth of velocity perturbations is primarily driven by baroclinic instability. It gives rise to high-latitude inertial modes in the form of retrograde polar vortices whose properties depend on the imposed shear. Equatorial Rossby modes are also excited, albeit with lower intensity than their high-latitude counterpart. Perturbations with arbitrary azimuthal wavenumbers lead to the excitation of Rossby modes for all available wave numbers, sustained by both direct and inverse energy cascades. In simulations with stronger shear, the high latitude modes produce Reynolds stresses able to modify the imposed differential rotation and accelerate the rotation of the poles.

The striations in the dust tails of comets are referred to as striae, and their origin has long been a mystery. We introduce a new dynamic model to describe the forms of the striae observed in comets Hale-Bopp (C/1995 O1), West (C/1975 V1), and Seki-Lines (C/1962 C1). Charged particles made of refractory materials, with radii less than 0.5 $\mu m$, are expelled from the comet's nucleus and accelerated by Lorentz forces near the nucleus. These particles decay many times to form striae, which have a lifespan of less than about 100 days at a distance of 1 astronomical unit from the sun. Over time, they continue to decay and eventually disappear from view. The following dynamic model explains these material science processes. Particles expelled from the comet's nucleus are subjected to three forces: solar gravity, solar radiation pressure, and Lorentz forces near the nucleus. As these particles decrease in size, the Lorentz forces and radiation pressure cause fluctuations, increasing and decreasing to form striae. This model, which is less of a dynamic approximation than previous theories (FLM3), explains the structure of the striae, enables predictions of their luminosity, and clarifies their origin.

Although triple systems are common, their orbital dynamics and stellar evolution remain poorly understood. We investigated the V1371 Tau system using TESS photometry, multi-epoch spectroscopy, and recent interferometric data, confirming it as a rare triple system consisting of an eclipsing binary orbited by a classical Be star, with a spectral classification of (B1V + B0V) + B0Ve. The eclipsing binary exhibits an orbital period of approximately 34 days, and the Be star orbits the inner pair on a timescale of a few years. Weak H$\alpha$ emission lines suggest the presence of a Keplerian disk with variability on a timescale of months around the Be star, and a nearly constant V/R ratio with no detectable asymmetry variations. Besides the eclipses, frequencies at 0.24 and 0.26 c/d dominate the photometric variability. Higher-frequency signals are present which appear associated with non-radial pulsation. The eclipsing pair ($i \approx 90^\circ$) shows projected rotational velocities of 160 and 200 km s$^{-1}$. The Be star's measured $v \sin i \approx 250$ km s$^{-1}$ implies a critical rotation fraction between 0.44 and 0.76 for plausible inclinations, significantly faster than the eclipsing components. The shallower eclipses in the KELT data compared to TESS suggest a variation in orbital inclination, possibly induced by Kozai-Lidov cycles from the outer Be star. The evolution analysis suggests that all components are massive main-sequence stars, with the secondary star in the eclipsing binary being overluminous. This study emphasizes the complexity of triple systems with Be stars and provides a basis for future research on their formation, evolution, and dynamics.

We investigate the small, quasi-periodic modulations seen in the gravity-mode period spacings of pulsating stars. These ``wiggles'' are produced by buoyancy glitches -- sharp features in the buoyancy frequency ($N$) caused by composition transitions and the convective--radiative interface. Our method takes the Fourier transform of the period-spacing series, $FT(\Delta P_k)$ as a function of radial order $k$. We show that $FT(\Delta P_k)$ traces the radial derivative of the normalized glitch profile $\delta N/N$ with respect to the normalized buoyancy radius; peaks in $FT(\Delta P_k)$ therefore pinpoint jump/drop locations in $N$ and measure their sharpness. We also note that the Fourier transform of relative period perturbations (deviations from asymptotic values), $FT(\delta P/P)$, directly recovers the absolute value of the glitch profile $|\delta N/N|$, enabling a straightforward inversion for the internal structure. The dominant $FT(\Delta P_k)$ frequency correlates tightly with central hydrogen abundance ($X_c$) and thus with stellar age for slowly pulsating B-stars, with only weak mass dependence. Applying the technique to MESA stellar models and to observed slowly pulsating B-stars and $\gamma$ Dor pulsators, we find typical glitch amplitudes $\delta N/N \lesssim 0.01$ and derivative magnitudes $\lesssim 0.1$, concentrated at chemical gradients and the convective boundary. This approach enables fast, ensemble asteroseismology of g-mode pulsators, constrains internal mixing and ages, and can be extended to other classes of pulsators, with potential links to tidal interactions in binaries.

Protostellar jets provide valuable insight into the evolutionary stage and formation history of star-forming cores in their earliest phases. We investigated the inner envelope structures of three extremely young protostars, selected for having the shortest dynamical timescales in their outflows and jets. Our analysis is based on Atacama Large Millimeter/submillimeter Array (ALMA) observations of the N2D+, DCO+, DCN, C18O, CH3OH, and H2CO lines, along with 1.3 mm continuum data, obtained at two spatial resolutions of ~500 AU and 150 AU. By examining molecular depletion and sublimation patterns, emission extents at core-scale and outflow rotational temperatures, we assessed the relative evolutionary stages of the three sources. In G208.68-19.20N1, the absence of N2D+ toward the core-despite a semi-ring-like distribution-and the presence of bright DCN and DCO+ emission cospatial with C18O indicate a warmer envelope, possibly suggesting a more advanced evolutionary state. In contrast, G208.68-19.20N3 shows no dense central structures in C18O, DCN, DCO+, or N2D+, with emission instead appearing scattered around the continuum and along large-scale filaments, consistent with a likely younger stage than G208.68-19.20N1. The third source, G215.87-17.62M, exhibits compact C18O emission at the continuum peak, but spatially extended N2D+, DCN, and DCO+ along the continuum, pointing to a cooler envelope and likely the youngest stage among the three. This comparative analysis across three protostars demonstrates the effectiveness of molecular tracers for evolutionary staging, though variations in luminosity or accretion may also shape chemical morphologies. These results highlight the promise of broader surveys for advancing our understanding of early protostellar evolution.

Axions or axion-like particles (ALPs) are well-motivated dark matter (DM) candidates whose coupling to photons induces periodic oscillations in the polarization angle of astrophysical light. This work reports the first search for such a signature using ten years of optical polarimetric monitoring of the blazar 1ES 1959+650. No statistically significant periodicity is detected using a Lomb-Scargle periodogram and Monte Carlo analysis. Assuming a central DM density in the host galaxy, this null result places tight upper limits on the ALP-photon coupling constant at $g_{a\gamma}<(5.8 \times 10^{-14}-1.8\times 10^{-10})\,\mathrm{GeV}^{-1}$ across a broad ALP mass range of $m_a \sim (1.4\times10^{-23}-5.2\times10^{-20})\,\mathrm{eV}$. Our constraints surpass those from Very Long Baseline Array polarimetry of active galactic jets and are competitive with those from long-term Galactic pulsar timing of PSR J0437-4715 over the same ALP mass window. These results establish long-term blazar polarimetry as a competitive and complementary approach for probing axion-like DM on extragalactic scales.

We present the results of the 2023 spectroscopic reverberation mapping (RM) campaign for active galactic nuclei (AGN) of NGC 5548, continuing our long-term monitoring program. Using the Lijiang 2.4-meter telescope, we obtained 74 spectra with a median cadence of 1.9 days. Through detailed spectral decomposition, we measured the light curves of the optical continuum at 5100~Å and the broad He~{\sc ii}, He~{\sc i}, H$\gamma$, and H$\beta$ emission lines. The time lags of these lines relative to the continuum are measured as $1.3^{+1.6}_{-0.6}$, $2.3^{+1.5}_{-2.1}$, $10.0^{+2.0}_{-1.8}$, and $15.6^{+2.6}_{-2.9}$ days (rest-frame), respectively. Velocity-resolved lag profiles for H$\gamma$ and H$\beta$ were constructed. Combined with data from previous seasons (2015$-$2021), we find that the radial ionization stratification of the broad-line region (BLR) is stable; the average virial mass of the supermassive black hole in NGC~5548 is $(2.6\pm1.1)\times 10^{8}M_{\odot}$, consistent with the $M_{\rm BH}-\sigma_*$ relation; the broad He~{\sc ii} line exhibits the largest responsivity, followed by broad He~{\sc i} (or H$\gamma$) and H$\beta$ lines; the BLR kinematics show significant temporal evolution, transitioning from virialized motions to signatures of inflow and outflow. Furthermore, an analysis of 35 years of historical data confirms a 3.5-year time lag between variations in the optical luminosity and the BLR radius, potentially implicating the role of radiation pressure or dynamical structure changes in the inner accretion disk. Long-term campaign demonstrates that the BLR in NGC 5548 is a robust yet dynamically evolving entity, providing crucial insights into AGN structure and accretion physics.

As part of the New-ANGELS program, we systematically investigate the X-ray luminosity functions (XLFs) of 4506 X-ray sources projected within a radius of 2.5 deg centering on M31. We construct XLFs for different regions in the disk and halo of M31, accounting for the incompleteness with an effective sensitivity map. Assuming that the halo regions contain (mostly) foreground stars and background active galactic nuclei, they are taken as "background" for deriving the XLFs of the sources in the disk. Through modeling XLFs, we decompose the X-ray sources into distinct populations for each region. We find that low-mass X-ray binaries are the dominant X-ray population throughout the disk of M31. The XLFs of M31 reveal a consistently lower integrated LMXB luminosity per stellar mass ($\alpha_\mathrm{LMXB}$) compared to other galaxies, likely due to M31's prolonged period of quiescent star formation. Variations in the XLF shape and $\alpha_\mathrm{LMXB}$ across different regions of M31 suggest that the relationship between integrated luminosity and stellar mass may vary within the galaxy. Additionally, the relatively low integrated luminosity observed in the inner-arm region provides crucial evidence for a rapid fading of M31's LMXBs around 1 Gyr, a finding consistent with recent observations of other nearby galaxies.

The discovery of the large-scale structure has transformed our view of galaxy formation and evolution. Filaments of the cosmic web provide key environments that channel the growth of structures. Guided by predictions from cosmological simulations, we study the morphological distribution of galaxies in the Perseus-Pisces Supercluster, a prominent filamentary complex at 70 Mpc. We focus on how galaxy morphology and structural disturbances relate to position within the filament network and to proximity to dense nodes. Our sample is built from a spectroscopic catalogue cross-matched with deep r-band CFHT/MegaCam imaging from UNIONS and additional time, enabling the detection of low-surface-brightness features and extended outer structures. Morphologies are determined both visually and through structural parameters extracted from surface-brightness profiles using AutoProf and AstroPhot. The 3D filamentary skeleton of Perseus-Pisces is reconstructed with the DisPerSE algorithm, providing distances from each galaxy to the nearest filament and to group or cluster centres. The 3D mapping reveals a network of interconnected sub-filaments converging around the Pisces cluster, forming a complex, multi-branched structure that likely shapes environmental effects on galaxy evolution. We observe clear morphological and stellar-mass segregation: massive early-type galaxies (E/S0) concentrate along filament spines and near dense nodes, while late-type and irregular systems are more broadly dispersed. About 10-13% of galaxies show strong signs of gravitational interaction, with stellar-halo asymmetries particularly common in filaments and groups. These findings underline the dual influence of filamentary environments, which both host evolved early-type systems and foster local tidal interactions and pre-processing that modify galaxy morphology.

In this manuscript, we recheck the spectroscopic properties of SDSS J134733.36+121724.27 (4C+12.50), confirming the presence of the double-peaked [O~{\sc iii}]$\lambda\lambda4959,5007$Å doublet and a broad H$\alpha$. The former likely results from AGN-driven biconical outflows, while the absence of a broad H$\beta$ supports a classification of the source as a Type-1.9 AGN. We analyze its high-quality Sloan Digital Sky Survey (SDSS) optical spectrum after robustly subtracting host galaxy and AGN continuum contributions through a simple stellar population fitting method employing 39 templates and a power-law continuum. Each narrow line of the [O~{\sc iii}]$\lambda\lambda4959,5007$Å doublet is better described by two Gaussian components (blue-shifted and red-shifted) than by a single Gaussian, as confirmed by the F-test. Broad components are included for both H$\alpha$ and H$\beta$, but only H$\alpha$ reveals a significant detection, further supported by a comparison between the SDSS spectrum and that previously reported. These results support that the object is highly consistent with a Type-1.9 AGN classification, and the double-peaked [O~{\sc iii}] profiles are most likely produced by AGN-driven biconical outflows rather than by a rotating narrow-line region or a dual AGN merger system. Additional observations are still needed to strengthen these conclusions.

Magnetic braking (MB) mechanism plays a vital role throughout the evolution of low-mass X-ray binaries (LMXBs). Considering the standard MB prescription, the initial orbital periods of LMXBs that can evolve into binary millisecond pulsar (MSP) with He white dwarfs (WDs) and short orbital periods ($2-9~\rm hours$) are within an extremely narrow interval, which was named the fine-tuning problem. Employing the detailed binary evolution model, we investigate the evolution of LMXBs in both the standard and convection and rotation boosted (CARB) MB laws. In the standard MB case, it is difficult for donor stars to form a He core and exhaust H envelope through mass transfer at short orbital periods, making them semidetached systems. The CARB MB mechanism can drive LMXBs evolve toward compact detached MSP-WD systems in wide initial orbital periods, over which binary MSPs with long orbital periods will be produced. We obtain the initial parameter space of binary MSPs with He WDs in the initial orbital period and donor-star mass plane, which can be applied to future statistics study by population synthesis simulations. We also discuss a new relation between orbital period and WD mass, formation of persistent ultra-compact X-ray binaries with relatively long orbital periods, and detectability of compact MSP-WD systems as low-frequency gravitational wave sources.

The arrangement of M31's dwarf galaxies exhibits anisotropy, with the majority located in the hemisphere between the Milky Way and the host galaxy. This study aims to investigate whether M31's present location is aligned with the center of its distribution of dwarf galaxies. We use forward modeling to infer the center of the M31 satellite 3D spatial distribution, folding in the completeness of dwarf galaxy searches. We observe a displacement of the center of the satellite distribution, relative to the center of M31, of approximately 10--50 kpc towards the Milky Way. Nonetheless, the center of M31 remains compatible with the center of the dwarf galaxy distribution given the broad constraints on its position, with the significance of the shift ranging from $\leq 1\sigma$ to $1.9\sigma$, depending on the assumed form of the volumetric spatial distribution of satellites. If M31 is truly offset from its satellite system, a quadrupling of the number of known satellites would be necessary to infer a significant ($3\sigma$) offset. Hence, expanding the number of known dwarf galaxies is crucial to deepen our understanding of the distribution of M31 satellites and further shed on its peculiar structure.

We present updated transit timing measurements for the hot Jupiter WASP-135 b using three new ground-based transit observations obtained with Leia, a 0.6-meter telescope operated by NASA's Exoplanet Watch at the Table Mountain Facility. These observations, conducted as part of Exoplanet Watch citizen science initiative, were analyzed with the EXOplanet Transit Interpretation Code (EXOTIC) pipeline to generate high-quality light curves and extract precise mid-transit times. By combining our new data with previously published observations, we refined the planet's ephemeris, reducing uncertainties in both the orbital period and mid-transit time. Our final mid-transit value is 2460585.6563426 +/- 0.00001908 BJD_TDB and the final period value is 1.4013776 +/- 0.0000002 days. Our updated timing solution demonstrates a 92% reduction in mid-transit time uncertainty compared to the original discovery paper and improves the precision of transit forecasts through 2030 which is critical to ensure efficient scheduling of future missions, such as ESA's Ariel. This work highlights the critical role of ongoing ground-based observations by students and citizen scientists in maintaining accurate ephemerides, which are essential for planning future space-based follow-up with facilities such as the Hubble and James Webb Space Telescopes. The work in this paper was done as part of the SEDS-PH (Students for the Exploration and Development of Space-Philippines) Upskill Groups, which provides opportunities for Filipinos to participate in space-related projects.

The magnetorotational instability (MRI) plays a crucial role in the evolution of many types of accretion disks. It is often studied using ideal-MHD numerical simulations. In principle, such simulations should be numerically converged, i.e. their properties should not change with resolution. Convergence is often assessed via the MRI quality factor, $Q$, the ratio of the Alfvén length to the grid-cell size. If it is above a certain threshold, the simulation is deemed numerically converged. In this paper we argue that the quality factor is not a good indicator of numerical convergence. First, we test the performance of the quality factor on simulations known to be unconverged, i.e. local ideal-MHD simulations with zero net-flux, and show that their $Q$s are well over the typical convergence threshold. The quality-factor test thus fails in these cases. Second, we take issue with the linear theory underpinning the use of $Q$, which posits a constant vertical field. This is a poor approximation in real nonlinear simulations, where the vertical field can vary rapidly in space and generically exhibits zeros. We calculate the linear MRI modes in such cases and show that the MRI can reach near-maximal growth rates at arbitrarily small scales. Yet, the quality factor assumes a single and well-defined scale, near the Alfvén length, below which the MRI cannot grow. We discuss other criticisms and suggest a modified quality factor that addresses some, though not all, of these issues.

As part of an ongoing programme of observing detached eclipsing binary stars in the southern sky, we present the first analysis of spectroscopic observations of the Algol-type binary system DG Mic. A spectroscopic analysis of mid-resolution spectra allowed us to constrain the effective temperature of the primary component and to test the consistency of the system parameters with its spectral energy distribution (SED). Combined solutions of mid-resolution spectra and TESS, ASAS and WASP light curves imply a system of two almost identical components ($q$ = 0.99) in circular orbits. Our final model shows that the system is a detached binary star. The masses and radii of the primary and secondary components of DG Mic were derived to be 1.65($\pm$0.12) M$_\odot$, 1.64($\pm$0.18) M$_\odot$ and 1.63($\pm$0.10) R$_\odot$, 1.91($\pm$0.13) R$_\odot$, respectively. According to Geneva evolution models, both components of the system are main-sequence stars and their age is approximately 713 Myr.

Radio active galactic nuclei (AGNs) eject a huge amount of energy into the surrounding medium and are thought to potentially prevent gas cooling and maintain the quiescence of massive galaxies. The short-lived, sporadic, and anisotropic nature of radio activities, coupled with the detection of abundant cold gas around some massive quiescent galaxies, raise questions about the efficiency of radio feedback in massive galaxies. Here we present an innovative method rooted in artificial intelligence to separate galaxies in which radio feedback is effective (RFE), regardless of current radio emission, from those in which radio feedback is ineffective (RFI), according to their optical images. Galaxies categorized as RFE are all dynamically hot, whereas quiescent RFI (RFI-Q) galaxies usually have extended cold-disk components. At given stellar mass, dark matter halos hosting RFE galaxies are between four to ten times more massive than those of RFI-Q galaxies. We find, for the first time, that almost all RFE galaxies have scant cold gas, irrespective of AGN activity. In contrast, many RFI-Q galaxies are surrounded by substantial amounts of condensed atomic gas, indicating a different evolutionary path from RFE galaxies. Our finding provides direct and compelling evidence that a radio AGN has gone through about 300 on-off cycles and that radio feedback can prevent gas cooling over a timescale much longer than that of radio activity. Contrary to general belief, our analysis shows that only a small fraction of massive galaxies are influenced by strong radio AGNs, suggesting that current galaxy formation models need serious revision.

BL Lacertae is not only archetypical of an entire class of jet-dominated active galactic nuclei, blazars, but also one of the most active and rapidly changing objects in this class. In the fall of 2024 (September--November), BL Lacertae underwent another episode of strong optical activity, reaching an R-band magnitude of about 12 and showing extremely rapid and large-amplitude inter- and intra-night flux and polarization variations. During this period, the object was monitored over 40 nights using telescopes with an aperture of up to 2 m at three observatories: Rozhen and Belogradchik in Bulgaria and Skinakas in Greece. The results from this study include some of the most spectacular intra-night variability episodes detected in a blazar. These rapid variations, combined with high photometric accuracy and high time resolution, allowed for confirmation of consistency between different optical bands with zero time delays, down to a minute scale. Unlike previous activity reports, polarization was relatively stable on these short time-scales. Possible connections between polarization, flux, and intra-night variability were explored in order to better model or constrain the physical processes and emission mechanisms in the relativistic jets.

We investigate the formation of dust gaps in circumstellar disks driven by the presence of multiple low-mass planets, focusing on the distinct physical mechanisms that operate across different gas-dust coupling regimes. We performed 2D hydrodynamical simulations of multiple planets embedded in a circumstellar disk using the PLUTO code, with the addition of dust treated as Lagrangian particles with a multi-size distribution. We carried out a large parameter space analysis to check the influence of disk and planetary properties on the dust component. Planets with $m \gtrsim 1 \, M_{\oplus}$ can open dust gaps for small grains in dense and warm disks (strong coupling) and for large grains in thin and cold disks (weak coupling), without significantly perturbing the gas. In the strong coupling regime, rapid Type I migration can shift the gap location inward or outward with respect to the planetary orbit, depending on the direction of migration. We also find dust gaps that overlap with Lindblad resonances. In the weak coupling regime, planets can create an inner dust cavity, multiple dust rings, or hide inside a common gap. Our results show how low-mass multi-planet systems perturb the dust distribution, which cannot be explained by considering each planet in isolation and has a crucial dependence on local disk conditions and dust grain sizes.

We present new numerical-relativity simulations of a magnetized binary neutron star merger performed with AthenaK. The simulations employ a temperature- and composition-dependent tabulated nuclear equation of state, with initially dipolar fields with a maximum initial strength of ${\sim}10^{16}\ {\rm G}$ which extend outside the stars. We employ adaptive mesh refinement and consider three grid resolutions, with grid spacing down to $\Delta x_{\rm min} \simeq 92\ {\rm m}$ in the most refined region. When comparing the two highest resolution simulations, we find orbital dephasing of over 7 orbits until merger of only $0.06$ radians. The magnetic field is amplified during the merger and we observe the formation of a magnetized funnel in the polar region of the remnant. Simulations are continued until about $30$ milliseconds after merger. However, due to significant baryonic pollution, the binary fails to produce a magnetically-dominated outflow. Finally, we discuss possible numerical and physical effects that might alter this outcome.

It remains debatable how billion-solar-mass supermassive black holes (SMBHs) form and evolve within the first billion years. We report results from a James Webb Space Telescope (JWST)/NIRSpec integral field unit (IFU) survey of 27 luminous quasars at $z \sim 5$-$6$, enabling a systematic investigation of their key physical properties and the associated, extended line emission. Our sample hosts SMBHs with $\log(M_{\mathrm{BH}}/M_\odot) \sim 8.6$-$9.7$ and Eddington ratios of $\sim 0.1$-$2.6$ based on H$\beta$, and the H$\beta$-based and H$\alpha$-based BH mass are broadly consistent with each other. Our sample may have a slightly smaller median BH mass and larger median Eddington ratio than lower-redshift quasars within the same luminosity range, although the difference could still be explained by statistical uncertainties. They generally follow the empirical correlations between [O III] $\lambda$5007 equivalent width and bolometric luminosities or Eddington ratios formed by lower-redshift quasars. The majority of them fall within the Eigenvector~1 planes formed by lower-redshift quasars. Nevertheless, a subset of the sample shows enhanced, blueshifted [O III] emission associated with fast outflows. Spatially extended [O III] line emission is detected in 6 objects and shows morphologies and kinematics consistent with merging activities and/or turbulent and clumpy interstellar media (ISM). Tentative evidence of quasar radiative feedback shaping the ISM of a merging companion galaxy is seen in the object with the most extended [O III] emission. Our results provide crucial insight into the rapid growth of SMBHs and the gaseous environments they reside in at z$\sim$5-6.

The dynamics of globular clusters in the Fornax dwarf galaxy pose a challenge for the standard cold dark matter (CDM) and can be used to test other models of dark matter. We study this dynamics in the context of ultralight bosonic dark matter model, accounting for the damping term in a generalized Gross-Pitaevskii equation. Employing analytic formulas for the dynamical friction force, the infall time and evolution of globular clusters are compared in the cases with and without the damping term. It is argued that the damping term plays an important role for the Fornax timing problem in ultralight dark matter models.

The Search for Extraterrestrial Intelligence (ETI) is, historically, a search for aliens like us, inspired by human centric ideas of intelligence and technology. However, humans are not the only instance of an intelligent, communicating species on Earth, and thus not guide to how we might think about ETI. Here, we explore the potential for the study of non-human species to inform new approaches in SETI research, using firefly communication patterns as an illustrative example. Fireflies communicate their presence through evolved flash patterns distinct from complex visual backgrounds. Extraterrestrial signals may also be identifiable not by their complexity or decodable content, but by the structural properties of the signal, as currently being explored in efforts to decode communication in non-human species across our biosphere. We present a firefly-inspired model for detecting potential technosignatures within environments dominated by ordered astronomical phenomena, such as pulsars. Using pulsar data from the Australia Telescope National Facility, we generate simulated signals that exhibit evolved dissimilarity from the surrounding pulsar population. This approach shifts focus from anthropocentric assumptions about intelligence toward recognizing communication through its fundamental structural properties, specifically, evolutionarily optimized contrast with natural backgrounds. Our model demonstrates that alien signals need not be inherently complicated nor need we decipher their meaning to identify them; rather, signals might be distinguishable as products of selection. We discuss implications for broadening SETI methodologies, leveraging the diverse forms of intelligence found on Earth.

It is well-known that some star clusters contain composite stellar populations (CSPs), in which the metallicities or (and) ages of stars are different. The formation and evolution of such clusters and their stellar populations remain unclear. Both single and binary cluster channels may lead to such CSPs. In order to simulate the formation and evolution of such CSPs in star clusters, this work develops a code of direct N-body simulation of CSPs, NbodyCP. It is applied to different clusters, in particular, to binary clusters. It shows that CSPs and different kinds of cluster pairs can be formed via dynamical processes. This will help to partially explain the formation of CSPs and various clusters. Some special cluster structures, e.g., two cores or bar-like shape, are shown to be the results of evolution of some binary clusters. The simulation also shows that the separation between the members of a binary cluster affects the time of two member clusters to combine or move away significantly.

Traditional cosmological hydrodynamical simulations usually assume equal-numbered but unequal-mass dark matter and baryonic particles, which can lead to spurious collisional heating due to energy equipartition. To avoid such a numerical heating effect, a simulation setup with equal-mass dark matter and baryonic particles, which corresponds to a particle number ratio of $N_{\rm DM}:N_{\rm gas} = \Omega_{\rm cdm} / \Omega_{\rm b}$, is preferred. However, previous studies have typically used grid-based particle loads to prepare such initial conditions, which can only reach specific values for $N_{\rm DM}:N_{\rm gas}$ due to symmetry requirements. In this study, we propose a method based on the glass approach that can generate two-component particle loads with more general $N_{\rm DM}:N_{\rm gas}$ ratios. The method simultaneously relaxes two Poisson particle distributions by introducing an additional repulsive force between particles of the same component. We show that the final particle load closely follows the expected minimal power spectrum, $P(k) \propto k^{4}$, exhibits good homogeneity and isotropy properties, and remains sufficiently stable under gravitational interactions. Both the dark matter and gas components individually also exhibit uniform and isotropic distributions. We apply our method to two-component cosmological simulations and demonstrate that an equal-mass particle setup effectively mitigates the spurious collisional heating that arises in unequal-mass simulations. Our method can be extended to generate multi-component uniform and isotropic distributions. Our code based on Gadget-2 is available at this https URL .

Context. While most chemical abundance studies of Cepheids rely on optical spectroscopy, near-infrared (NIR) observations offer advantages in terms of reduced extinction and access to new elemental tracers. Aims. We aim to validate NIR-based abundance determinations against optical results and to explore the diagnostic power of spectral lines inaccessible in the optical domain. The H and K bands allow us to trace elements such as P, K, and Yb, while also probing obscured Galactic regions and more distant Cepheids. Methods. We obtained high-resolution (R=45000) H- and K-band spectra for 21 Galactic and 2 LMC Classical Cepheids using IGRINS. Atmospheric parameters were derived from photometry and line-depth ratios (Teff), empirical calibrations (log g), and spectral fitting. Abundances of 16 elements were determined via LTE full spectral synthesis and compared with optical literature values. Results. We find excellent agreement between NIR and optical abundances, confirming the reliability of IGRINS-based measurements. The Fe, Mg, and Si gradients match previous optical determinations. We provide the first homogeneous NIR-based measurements of P, K, and Yb in Cepheids, consistent with chemical evolution models. The two LMC Cepheids in our sample, also studied optically, serve as extragalactic benchmarks for validating NIR abundances in low-metallicity regimes. Conclusions. High-resolution NIR spectroscopy yields accurate chemical abundances in Cepheids, consistent with optical results, and grants access to additional nucleosynthetic tracers. These results support future large NIR spectroscopic surveys with instruments such as MOONS, ELT, and JWST for Galactic and extragalactic archaeology.

This is a transcript of the joint talk we gave at the Sixth Gruber Cosmology Conference at Yale University on 3 October 2025. We describe the key role played by Big Bang Nucleosynthesis (BBN) in today's `Precision Cosmology', focusing in particular on the precise determination of the primordial abundance of deuterium. We describe the development of the ideas and methods of BBN research from their beginnings more than 75 years ago to the latest developments, and conclude with a forward look to likely advances expected towards the end of the current decade.

We seek to exploit the expanded observational range of the MeerKAT radio telescope with the new S-band receivers (2.0-2.8 GHz). To showcase its enhanced capabilities, we conducted new S-band observations of the galaxy NGC 2997 in full polarization. The S band is ideal for studying magnetic fields in spiral galaxies due to the weak Faraday depolarization. Performing a rotation measure (RM) synthesis allowed us to measure Faraday RMs in the galaxy, a signature of regular magnetic fields. A fast Fourier transform (FFT) algorithm was used to study the various azimuthal modes found in the RM data of the galaxy. The RM synthesis analysis indicates the direction of the magnetic field along the line of sight throughout the entire disk. Leveraging the sensitivity and high resolution provided by MeerKAT's S-band capability, this study achieves an unprecedented level of detail of the magnetic field structure. Our sector-based analysis of the RMs across azimuthal regions reveals the existence of modes of the large-scale magnetic field in NGC 2997. The variations in the RM values along the azimuthal angle reveal smoothly changing phase shifts between the rings, without the previously reported field reversal at about 3 kpc radius between the central region and disk. In this work, for the first time, a Fourier analysis has been applied to RM data averaged in sectors of rings in the disk plane of a spiral galaxy. Our Fourier analysis of the RM map shows three different large-scale field modes detected in the disk of NGC 2997. After applying a geometric modification, even multiples of the first mode were detected, as predicted from theoretical studies of dynamo action in a spiral galaxy with symmetric spiral structure. Our new method opens up new possibilities for investigating magnetic fields in spiral galaxies.

We perform broadband spectral and timing studies of the Galactic low-mass black hole candidate AT2019wey during its 2022 outburst, using quasi-simultaneous observations from NICER, Swift, and NuSTAR. The long-term MAXI light curve, along with the hardness-intensity diagram (HID) derived from NICER data, indicates that the source remained in the hard state and did not switch to the soft state. Spectral modeling using two different model combinations reveals that the broadband spectrum is best described by two distinct Comptonizing regions, associated reflection components, and thermal emission from the disk. The harder Comptonizing region dominates ($\gtrsim88\%$) the total flux and is primarily responsible for the observed reflection features from the distant part of the disk. We find that the accretion disk is truncated at a radius of $\sim16-56~r_{\rm{g}}$, while the luminosity is $\sim1.9\%$ of the Eddington limit. Our spectral results also show consistency in the estimated inner disk radius obtained through two independent methods: modeling the disk continuum and the reflection spectrum. The variability studies imply the presence of intrinsic disk variability, likely originating from an instability in the disk. We also detect hard time lags at low frequencies, possibly arising from the inward propagation of mass accretion rate fluctuations from the outer to the inner regions of the accretion disk. Moreover, an observed deviation of the lag-energy spectrum from the log-linear trend at $\lesssim 0.7$ keV is most likely attributed to thermal reverberation, arising from the reprocessing of hard coronal photons in the accretion disk.

We analyzed TESS archival data of three novae after recent outbursts, searching the orbital and white dwarf (WD) rotation period and possible variations of these periods. In V1405 Cas, we detected a period of $\sim$116.88 seconds, which we identified as due to the WD spin, and measured a rate of increase of 0.001542$\pm0.000009\, {\rm s\, d}^{-1}$, one the fastest spin-down rates ever recorded. The rapid spin-down coupled with an X-ray luminosity several orders of magnitude lower than the available spin-down power, strongly indicates that the system is in a magnetic ``propeller'' state, namely the rotational energy powers the system's X-ray luminosity. We measured a previously unknown orbital period of 1.36 days for V1716 Sco. If the X-ray flux modulation with a period of 77.9 s detected in outburst for this nova is due to the rotation of an strongly magnetized white dwarf as in other novae with similar modulations of the supersoft X-ray source in outburst, the system is in a parameter space that challenges standard models of cataclysmic variable evolution. For V1674 Her, which has already been classified as an intermediate polar (IP), we confirm the known spin period of 501.33$\pm$0.01 s and the orbital period of 0.1529$\pm$0.0001 days, suggesting that the spin modulation was also the root cause of the periodicity in X-rays in outburst, and that the WD atmosphere in the supersoft X-ray phase was not thermally homogeneous. Our results highlight the power of high-cadence, continuous observations in revealing extreme and unexpected characteristics of accreting white dwarfs.

The black hole shadow, a direct probe of the event horizon's gravitational influence, has been observationally confirmed by the Event Horizon Telescope (EHT). While theoretical models of shadows in vacuum are mature, real astrophysical black holes like M87* and Sgr A* are enveloped in plasma, which can alter photon trajectories through dispersion. Current understanding, based on foundational work, indicates that only specific plasma distributions allow for an analytical treatment via the separation of the Hamilton-Jacobi equation. In this work, we build upon this framework to systematically investigate the propagation of light rays in Kerr spacetime surrounded by a pressureless, non-magnetized cold plasma. We explicitly derive the separability condition, identifying the exact class of plasma densities that permit a generalized Carter constant. For these models, we compute the photon regions and shadow boundaries, characterizing how the shadow's size and shape deviate from the vacuum case in a frequency-dependent manner. Our results provide analytical benchmarks for the distortion of shadows in dispersive media and determine the critical plasma frequency beyond which the shadow is erased, offering a direct link between observable shadow features and the properties of the ambient plasma environment and providing a foundation for studying more dynamic, non-separable plasma distributions.

2MASS J05513444+4135297 (herafter J0551+4135) is the only pulsating DAQ white dwarf known with a carbon and hydrogen atmosphere. Its unusual atmospheric composition and kinematics indicate a white dwarf merger origin. We present time-series photometry of J0551+4135 obtained using the Apache Point Observatory 3.5m, Gemini North 8m, and Gran Telescopio Canarias 10m telescopes. J0551+4135 exhibits variations in pulsation amplitude and frequency over time. We detect ten significant recurring peaks across different subsets of observations, with frequencies ranging from 987 to 1180~$\mu$Hz, consistent with non-radial gravity ($g$)-mode oscillations. We present new evolutionary models suitable for spectroscopic characterization of DAQ white dwarfs, and derive a mass of $1.13 \pm 0.01\,M_\odot$ and a cooling age of $1.7 \pm 0.1$ Gyr for a CO core, and $1.12 \pm 0.01\,M_\odot$ and $1.6 \pm 0.1$\,Gyr for an ONe-core white dwarf, respectively. However, detailed asteroseismology of this unique pulsator has to wait until fully-consistent DAQ evolutionary models are available. Further observations, including multi-site campaigns to reduce daily aliasing and to improve the signal-to-noise ratio would be helpful for identification of additional modes and constraining the internal structure of this unique pulsator.

We investigate neutron stars that contain a unified dark sector composed of cold, degenerate fermionic dark matter and a vacuum-like dark-energy component. Within a general-relativistic two-fluid framework that allows a covariantly conserved, gradient-driven energy exchange between baryons and the dark sector, we quantify how dark microphysics reshapes global structure when the total gravitational radius need not coincide with the luminous baryonic radius. Using a state-of-the-art baryonic equation of state, we explore the halo-forming mass range for fermionic dark matter with particle masses of 400 MeV and 1 GeV, and we characterize sequences by the difference between the total and luminous radii and by the fractional difference between the total and baryonic masses. We confirm established trends: lighter fermions typically support low-density halos that increase the total radius by several kilometers at nearly fixed mass, whereas masses near 1 GeV tend to shrink halos and make the two radii appreciably closer. Our central new result is that a percent-level vacuum-like admixture markedly reduces halo formation, shrinking the radius difference from several kilometers to sub-kilometer scales and the fractional mass difference to $\lesssim 1\%$. Combined gravitational-wave and X-ray observations offer a practical route to bound the halo size and the allowed vacuum-like fraction.

Close-in transiting sub-Neptunes are abundant in our galaxy \cite{fulton2017california}. Planetary interior models based on their observed radius-mass relationship suggest that sub-Neptunes contain a discernible amount of either hydrogen (dry planets) or water (wet planets) blanketing a core composed of rocks and metal \cite{bean2021nature}. Water-rich sub-Neptunes have been believed to form farther from the star and then migrate inward to their present orbits \cite{bitsch2021Dry}. Here, we report experimental evidence of reactions between warm dense hydrogen fluid and silicate melt that releases silicon from the magma to form alloys and hydrides at high pressures. We found that oxygen liberated from the silicate melt reacts with hydrogen, producing a significant amount of water up to a few tens of weight percent, which is much greater than previously predicted based on low-pressure ideal gas extrapolation \cite{misener2023Atmospheresa,schlichting2022Chemical}. Consequently, these reactions can generate a spectrum of water contents in hydrogen-rich planets, with the potential to reach water-rich compositions for some sub-Neptunes, implying an evolutionary relationship between hydrogen-rich and water-rich planets. Therefore, detection of a large amount of water in exoplanet atmospheres may not be the optimal evidence for planet migration in the protoplanetary disk, calling into question the assumed link between composition and planet formation location.

Coronal mass ejections (CMEs) are the main drivers of disturbances in the solar heliosphere because they propagate and interact with the magnetic field of the solar wind. It is crucial to investigate the evolution of CMEs and their deformation for understanding the interaction between the solar wind and CMEs. We quantify the effect of the dynamic solar wind on the propagation of a CME in the heliosphere with a hydrodynamic plasma cloud-cone model and a linear force-free spheromak model at various locations in the heliosphere. We chose a CME event that launched on SOL2021-09-23T04:39:45 and was observed by multiple spacecraft, namely BepiColombo, Parker Solar Probe, Solar Orbiter, Stereo A and ACE. The solar wind was modelled in the steady and dynamic regimes in the Icarus model. The CME parameters were approximated for the selected event, and two CME models (spheromak and cone) were launched from the inner heliosphere boundary. The obtained synthetic in situ measurements were compared to the observed in situ measurements at all spacecraft. The internal magnetic field of the flux rope was better reconstructed by the spheromak model than by the cone CME model. The cone CME model maintained a nearly constant longitudinal angular extension while somewhat contracting in the radial direction. In contrast, the spheromak model contracted in the longitudinal direction while expanding in the radial direction. The CME sheath and magnetic cloud signatures were better reproduced at the four spacecraft clustered around the CME nose by the spheromak CME model. The dynamic solar wind caused a greater deceleration of the modelled CME than the steady-state solar wind solution. Because the background was homogeneous, the modelled CME properties were only mildly affected by the solar wind regime, however.

Coronal modelling is crucial for a better understanding of solar and helio-physics. Due to the strong brightness of the Sun and the lack of white light observations of the solar atmosphere and low corona (1-1.5R$_\odot$), total solar eclipses have become a standard approach for validating the coronal models. In this study, we validate the COCONUT coronal model by predicting the coronal configuration during the total solar eclipse on April 8, 2024. We aim to predict the accurate configuration of the solar corona during the total solar eclipse on April 8, 2024. We utilise the full 3D MHD model to reconstruct the solar corona from the solar surface to $30\;R_\odot$. The upcoming total solar eclipse predictions were conducted in three different regimes: quasi-steady driving of the inner boundary conditions (BCs) with a daily cadence and dynamic driving of the inner BCs with both daily and hourly cadences. The results from all the simulations are compared to the total solar eclipse images. Additionally, the synthetic white-light (WL) images are generated from the STEREO-A field of view and compared to COR2 observed images. Normalised polarised brightness is compared in the COR2 and synthetic WL images. The predicted solar corona does not vary significantly in the first half of the prediction window. The dynamic simulations yielded better results than the quasi-steady predictions. The west limb was reconstructed better in the simulations than the east limb. We have predicted the total solar eclipse coronal configuration 18 days before the total solar eclipse. We can conclude that the dynamic simulations produced more accurate predictions. The availability of comprehensive observations is crucial, as the emergence of the active region on the east limb made it difficult to accurately predict the east limb coronal configuration due to incorrect input of magnetic field data.

Hyperluminous infrared galaxies (HyLIRGs; SFRs up to about 1000 Msun yr-1), though rare, provide key constraints on galaxy evolution. H-ATLAS J084933.4+021443, a z = 2.41 binary HyLIRG (galaxies W and T) with two additional luminous companions (C and M), offers an ideal laboratory for studying star formation during "cosmic noon". We use ALMA to obtain resolved imaging and kinematics of CO J:7-6, [C I] 2-1, H2O, and rest-frame 340-1160 GHz continuum emission in all four galaxies. Each system is spatially resolved within ~0.3 arcsec (2.5 kpc) apertures. Gas kinematics in W and T are rotation-dominated, with galaxy T showing emission extended along its kinematic minor axis due to lensing magnification. Spatially resolved SEDs indicate that W is well fitted by single-temperature greybody dust despite hosting a luminous AGN, while T requires an additional hot-dust component and extra millimetre emission. We confirm [C I] J:2-1 as a tracer of warm/dense molecular gas in these extreme systems, though its luminosity ratio with CO J:7-6 rises sub-linearly. We derive resolved (2.5 kpc-scale) Schmidt-Kennicutt (SK) relations for W and T using both cold and warm/dense gas, finding depletion times of about 50-100 Myr (W) and about 100-500 Myr (T). Both galaxies follow a steep SK relation with power-law index n ~ 1.7, significantly above the n ~ 1 observed in normal star-forming galaxies.

Aims. This paper introduces LRPayne, a novel algorithm designed for the efficient determination of stellar parameters and chemical abundances from low-resolution optical spectra, with a primary focus on data from large-scale galactic surveys such as WEAVE. Methods. LRPayne employs a model-driven approach, utilising a fully connected artificial neural network (ANN), trained on a library of 70,000 synthetic stellar spectra generated using iSpec with 1D MARCS model atmospheres and the Turbospectrum synthesis code. The network is trained to predict normalized flux given stellar labels (Teff, log(g), [Fe/H], vmic, vmax and v sin i, and 24 individual elemental abundances). Stellar parameters are subsequently derived from observed spectra by finding the best-fit synthetic spectrum from the ANN using a chi-squared minimisation technique. The method operates on spectra degraded to a resolution of R=5000 covering the wavelength range 4200-6900 Å. Results. Internal accuracy tests on synthetic spectra show a median interpolation error of less than 0.13 % for 90 % of the validation sample. The method accurately recovers most input labels from synthetic spectra, even at a signal-to-noise ratio (S/N) of 20, with some expected challenges for elements like Li, K, and N. Validation on observed spectra of 25 Gaia FGK benchmark stars and 42 metal-poor stars reveals good agreement with literature values. For stellar parameters, mean differences are 22+-87 K for Teff , 0.19+-0.23 dex for log(g), and 0.01+-0.17 dex for [Fe/H]. Abundances for elements like Na, Mg, Si, and most Fe-peak elements (Cr, Ni, V, Sc) are well-recovered. Challenges are noted for oxygen, manganese in metal-rich giants, aluminium in metal-poor stars and dwarfs, and for deriving log g in hot metal-poor dwarfs, partly due to non-local thermodynamic equilibrium effects and line characteristics.

The formation channels of magnetars remain an open question. Although core collapse supernovae of isolated massive stars are important, binary interactions -- such as tidal interaction, common envelope evolution, and stellar mergers -- may also play a significant role in making magnetars. Understanding the relative contributions of these channels is crucial for linking magnetars to their observed properties and host environments. In this paper, we investigate potential magnetar formation channels using population synthesis simulations, considering both single-star and isolated binary system evolution. By conducting simulations with different parameters, we compare the effects of various evolution processes on magnetar formation. Additionally, we study the delay times and kick velocities across all formation channels, analyze the orbital properties and companion types of surviving magnetar binaries. We find that the majority of magnetars are observed as single objects ($\geq 90\%$), although a large fraction of them were originally in binary systems and experienced either kick disruption or merger. Surviving binaries are most likely to host main-sequence companions and exhibit different distributions of eccentricities due to different supernova mechanisms. These findings show the critical role of binary evolution in magnetar formation and provide predictions for the properties of magnetar populations that can be tested with future observations.

We investigated Gaia-Enceladus/Sausage globular cluster samples and studied their orbital and dynamical evolution over cosmological timescales in external time-variable potential. We estimated the limits of distribution of the escaped stars from the globular clusters' orbital evolution in energy angular momentum space. To reconstruct the orbital evolution of the known globular clusters of the dwarf galaxy Gaia-Enceladus/Sausage, we used the parallel $N$-body code $\varphi$-GPU. We investigated the relationship between globular clusters and their progenitor by analysing their orbital parameters and phase-space distribution during 9 Gyr of evolution in the past. We created a $N$-body model of Gaia-Enceladus/Sausage globular clusters and analysed their dynamical evolution and distribution of the escaped stars today. We summarised the samples of the Gaia-Enceladus/Sausage globular clusters and created two main categories: `most probable' and `tentative', with 15 and 9 clusters, respectively. We analysed the evolution of their kinematic, orbital, and phase-space parameters in the external time-variable potential. We defined phase-space distribution limits of stars that escape from globular clusters during 9 Gyr of evolution: a specific energy from -18 to -12.2 $\times10^4$ km$^2$ s$^{-2}$, L$_{\rm z}$ from -0.98 to 0.72 $\times10^3$ kpc km s$^{-1}$, and L$_{\rm perp}$ from 0 to 1.8 $\times10^3$ kpc km s$^{-1}$. The limits of the GE/S debris in Galactic area based on orbital parameters of the GC's escaped stars are: for apocentre and pericetre distances of 10--28 and 1--4 kpc, < 18 kpc in Galactocentric radius and < |15| kpc in the Z direction. Generally we compared the phase-space distribution of escaped stars from the GCs GE/S debris energy-angular momentum limits with the observed very metal-poor stars, which belong to the GE/S itself and produce consistent results.

High-resolution JWST images of nearby spiral galaxies reveal polycyclic aromatic hydrocarbon (PAH) emission structures that trace molecular gas, including CO-dark regions. We identify ISM cloud structures in PHANGS-JWST 7.7 $\mu$m PAH maps for 66 galaxies, smoothed to 30 pc and at native resolution, extracting 108,466 and 146,040 clouds, respectively. Molecular properties were inferred using a linear conversion from PAH to CO. Given the tendency for clouds in galaxy centers to overlap in velocity space, we opted to flag these and omit them from the analysis in this work. The remaining clouds correspond to giant molecular clouds, such as those detected in CO(2-1) emission by ALMA, or lower surface density clouds that either fall below the ALMA detection limits of existing maps or genuinely have no molecular counterpart. Cross-matching with ALMA CO maps at 90 pc in 27 galaxies shows that 41 % of PAH clouds have CO associations. The converted molecular properties vary little across environments, but the most massive clouds are preferentially found in spiral arms. Fitting lognormal mass distributions down to $2\times10^{3} M_{\odot}$ shows that spiral arms host the highest-mass clouds, consistent with enhanced formation in arm gravitational potentials. Cloud molecular surface densities decline by a factor of $\sim 1.5-2$ toward $2 - 3 R_{e}$. However, the trend largely varies in individual galaxies, with flat, decreasing, and even no trend as a function of galactocentric radius. Factors like large-scale processes and morphologies might influence the observed trends. We publish two catalogs online, one at the common resolution of 30 pc and another at the native resolution. We expect them to have broad utility for future PAH clouds, molecular clouds, and star formation studies.

We analyze the Starobinsky inflation model and the impact of curvature corrections, particularly a cubic $R^3$ term, to assess their behavior in light of the latest observational results from the Atacama Cosmology Telescope (ACT). With the recent sixth data release (DR6), the scalar spectral index was measured to be $n_s=0.9743 \pm 0.0034$, which appears to exclude the pure Starobinsky model at approximately the $2\sigma$ level. In this paper, we implement the Starobinsky inflationary potential directly into the CLASS code, without relying on the slow-roll approximation, and we constrain the number of e-folds of inflation $N_k$ using a theoretically motivated range derived from reheating considerations and standard couplings between matter fields and gravity. We show that it is still possible to identify a significant region of parameter space where the Starobinsky model remains highly consistent with the latest observational data. While the pure Starobinsky model remains a compelling candidate for cosmic inflation, we explore how including a cubic $R^3$ term can shift its predictions to better align with the Planck and ACT measurements.

The Sino-French SVOM (Space Variable Objects Monitor) mission is a space-based astronomy mission complemented with ground-based dedicated instrumentation. It aims to explore and study high-energy cosmic phenomena, such as gamma-ray bursts (GRBs). This unprecedented combination of space-based and ground-based instruments will provide leading multi-wavelength observational capabilities in gamma-rays, X-rays, optical, and near-infrared bands. The complete observation sequence of each GRB triggered by the SVOM mission consists of three stages, the GRB detections, followed by the on-board and grounded automatic follow-ups, and rapid deep multi-band photometry and spectroscopy re-visit observations. To efficiently organize all grounded instruments performing automatic follow-ups and re-visit observations, we develop a follow-up observation coordinating service (FOCS), which is capable of performing GRB trigger distributing, automatic observation scheduling and observation coordination supporting by providing a user support platform. The FOCS also facilitates the provision of observational planning for ground-based telescopes to conduct synchronized observations of identical celestial regions as SVOM. The FOCS is utilized for the SVOM-dedicated ground-based telescopes as well as for associated partner telescopes. Since the launch of SVOM in June 2024, as the FOCS system joining the operations of SVOM, multiple successful observations have been made for SVOM GRBs. In this paper, we present the goals of the FOCS system as well as the principle and workflow developed to achieve these goals. The structure, technical design, implementation, and performance of the FOCS system are also described in detail. We conclude with a summary of the current status of the FOCS system and our near-future development plan.

We have conducted a comprehensive comparison of interplanetary scintillation (IPS) observations taken by the Murchison Widefield Array (MWA) with several heliospheric transient event catalogues, over a time period of 7 months during solar minimum. From this analysis we have found that of the 84% of catalogued events that have MWA IPS data available, 68% of them appear in MWA observations. Of the enhancements first identified in IPS observations, only 58% have a potential match with a catalogued event. The majority of enhancements that were identified in the IPS observations were situated greater than 10$^\circ$ from the ecliptic plane. Two such features were selected for detailed analysis, connecting their solar origins to their propagation through the heliosphere. The first of these features was created by a coronal mass ejection (CME), captured over two successive MWA observations and recorded in several catalogues. The second feature has the potential of being a stream interaction region (SIR) travelling out of the ecliptic plane. This particular SIR was not recorded in any catalogue. Thus the MWA shows promise in detecting heliospheric transients that other commonly-used techniques may overlook. These results show the strength of the MWA in having unbridled access to the heliosphere, able to make remote observations of events far out of the ecliptic as it is not restrained to the orbits of spacecraft. We demonstrate how the inclusion of MWA IPS data can potentially boost the number of CME and SIR events that are characterised.

Following the identification of the first confirmed individual neutrino source, Seyfert galaxies have emerged as the most prominent class of high-energy neutrino emitters. In this work, we perform a detailed investigation of the outflow--cloud interaction scenario for neutrino production in Seyfert nuclei. In this framework, fast AGN-driven winds collide with clumpy gas clouds in the nuclear region, forming bow shocks that efficiently accelerate cosmic-ray protons. The accelerated protons subsequently interact with cold protons from the outflows via inelastic proton--proton ($pp$) collisions, producing high-energy neutrinos, while the photomeson ($p\gamma$) process with disk photons may provide a subdominant contribution at the highest energies. Applying this model to five neutrino-associated Seyfert galaxies, we successfully reproduce the observed TeV neutrino fluxes without violating existing gamma-ray constraints. By integrating over the Seyfert population using X-ray luminosity functions, we further demonstrate that Seyfert galaxies can account for a substantial fraction of the diffuse astrophysical neutrino background in the $10^4-10^5~{\rm GeV}$ energy range.

Pulsar searching with next-generation radio telescopes requires efficiently sifting through millions of candidates generated by search pipelines to identify the most promising ones. This challenge has motivated the utilization of Artificial Intelligence (AI)-based tools. In this work, we explore an optimized pulsar search pipeline that utilizes deep learning to sift ``snapshot'' candidates generated by folding de-dispersed time series data. This approach significantly accelerates the search process by reducing the time spent on the folding step. We also developed a script to generate simulated pulsars for benchmarking and model fine-tuning. The benchmark analysis used the NGC 5904 globular cluster data and simulated pulsar data, showing that our pipeline reduces candidate folding time by a factor of $\sim$10 and achieves 100% recall by recovering all known detectable pulsars in the restricted parameter space. We also tested the speed-up using data of known pulsars from a single observation in the Southern-sky MWA Rapid Two-metre (SMART) survey, achieving a conservatively estimated speed-up factor of 60 in the folding step over a large parameter space. We tested the model's ability to classify pulsar candidates using real data collected from the FAST, GBT, MWA, Arecibo, and Parkes, demonstrating that our method can be generalized to different telescopes. The results show that the optimized pipeline identifies pulsars with an accuracy of 0.983 and a recall of 0.9844 on the real dataset. This approach can be used to improve the processing efficiency for the SMART and is also relevant for future SKA pulsar surveys.

Complicated hardenings and softenings of the spectra of cosmic ray protons and helium have been revealed by the newest measurements, which indicate the existence of multiple source populations of Galactic cosmic rays. We study the physical implications of these results in this work. A phenomenological fitting shows that three components can properly give the measured structures of the proton and helium spectra. The data are then accounted for in a physically motivated, spatially-dependent propagation model. It has been shown that one background source population plus two local sources, or two background source populations plus one local source can well reproduce the measurements. The spectral structures of individual species of cosmic rays are thus natural imprints of different source components of cosmic rays. Combined with ultra-high-energy $\gamma$-ray observations of various types of sources, the mystery about the origin of Galactic cosmic rays may be uncovered in future.

Magnetars provide natural laboratories for strong-field quantum electrodynamics processes, such as vacuum polarization, which gives rise to vacuum resonance together with the plasma response. We develop a general framework to describe vacuum resonance in a three-component plasma consisting of ions, electrons, and positrons, as expected in baryon-loaded magnetar bursts. By introducing a parametrization of the plasma composition, we establish the general criterion for the occurrence of vacuum resonance in such plasmas. Our analysis encompasses both Mikheyev-Smirnov-Wolfenstein-like adiabatic mode conversion and nonadiabatic eigenmode transition, highlighting their dependence on the plasma composition. Applying this framework to baryon-loaded fireballs in magnetar bursts, we estimate the characteristic X-ray polarization signatures. Detection of these polarizations will provide observational signatures of vacuum polarization as well as baryon loading in magnetar fireballs.

We present a full-sky covariance-weighted analysis of redshift-frame consistency in the Pantheon+ Type~Ia supernova sample. Using 1,543 unique objects with heliocentric ($z_{\rm HEL}$) and cosmic microwave background ($z_{\rm CMB}$) redshifts, we quantify residual differences between frames. A statistically significant but physically small mean offset $\langle z_{\rm CMB} - z_{\rm HEL} \rangle = (-3.8 \pm 0.1)\times10^{-4}$ is found, exhibiting a sign reversal between low- and high-redshift subsets ($p = 3.8\times10^{-15}$). A dipole fit to the residuals yields an amplitude $A = (1.5 \pm 0.1)\times10^{-3}$ directed toward $(\mathrm{RA},\mathrm{Dec}) = (167.1^\circ, -1.6^\circ)$, consistent within $1^\circ$ of the CMB dipole. When propagated through a covariance-weighted Hubble fit, these effects shift the inferred Hubble constant by only $\Delta H_0 = 0.07~\mathrm{km\,s^{-1}\,Mpc^{-1}}$ (about $1.3\%$ of the current Hubble tension). The recovered dipole aligns with the known solar motion relative to the CMB, validating the kinematic frame corrections in Pantheon+ and establishing a systematic floor for future bulk-flow searches.

The goal of this paper is to obtain an approximate solution of the restricted three-body problem in the case of small perturbations in the vicinity of, but not in exact resonance. In this paper, we study the restricted threebody problem known as planetary type (i.e., when the eccentricity of the test particle is small). A method of linearizing the equation of motion close to (but not in) resonance is proposed under the assumption of small perturbations. In other words, we study orbits when the resonant argument circles the resonance. In the practically interesting case of resonant perturbations we can restrict our study to a perturbation with a single frequency with the largest amplitude, and reduce the problem to the Mathieu equation. The model qualitatively describes the behavior of the perturbation in the vicinity of the resonance. It can be used to estimate the exact position of the resonance and the boundaries between neighboring resonances.

Star-forming galaxies form tight relations between their stellar mass, star-formation rate, and molecular gas reservoir on global and resolved scales. On the path to quiescence, the exchange between gas and stars must inevitably be broken. Understanding the mechanisms governing star formation and quenching therefore requires observations of both the stellar and molecular gas components. To this end, we have assembled a sample of 277 galaxies ($0.02 \lesssim z \lesssim 0.25$) with semi-resolved optical and millimetre $^{12}$CO(1-0) data, wherein the properties of the inner $\thicksim$2 kpc can be distinguished from the outer regions. This effort was made possible by the Sloan Digital Sky Survey (SDSS) catalogues and the maturing archive of the Atacama Large (sub-)Millimetre Array (ALMA). We call this dataset the SDSS-ALMA Legacy Value Archival Gas Exploration (SALVAGE). In this work, we leverage SALVAGE to provide a semi-resolved perspective on global scaling relations and why some galaxies deviate from them. In agreement with previous work, we find that the offset of a galaxy from the global star-forming main sequence (SFMS) is driven by its inner star formation rate. With the relative inner and outer distributions of molecular gas fraction and star formation efficiency, we investigate whether the central star formation driving global changes is due to fuel availability or efficiency. We find that the position of a galaxy within the SFMS is largely due to the inner star-formation efficiency, while departure from the SFMS is driven by availability of central gas. The central few kpc are thus the most consequential region for galaxy evolution at low redshift.

We present 17 cataclysmic variables (CVs) obtained from the crossmatch between the Sloan Digital Sky Survey (SDSS) and eROSITA Final Equatorial Depth Survey (eFEDS), including 8 known CVs before eFEDS and 9 identified from eFEDS. The photometric periods of four CVs are derived from the Zwicky Transient Facility (ZTF) and Catalina Real-Time Transient Survey (CRTS). We focus on two CVs, SDSS J084309.3$-$014858 and SDSS J093555.0+042916, and confirm that their photometric periods correspond to the orbital periods by fitting the radial velocity curves. Furthermore, by the combination of the Gaia distance, the spectral energy distribution, and the variations of $\mathrm{H}\mathrm{\alpha}$ emission lines, the masses of the white dwarf and the visible star can be well constrained.

During its evolution, the Milky Way (MW) incorporated numerous dwarf galaxies, particularly low-mass systems. The surviving dwarf galaxies orbiting the MW serve as exceptional laboratories for studying the unique properties of these systems. Their metal-poor environments and shallow gravitational potentials likely drive significant differences in star formation and star cluster properties compared to those in the MW. Using high-quality near-infrared spectra from the APOGEE survey, we determined abundances of Fe, C, N, O, Mg, Al, Si, Ca, Ti, Cr, Mn, Ni, and Ce for 74 stars in four MW satellite dwarf galaxies: Fornax, Sextans, Draco, and Carina. Our analysis reveals that the distribution of $\alpha$ elements (e.g., [Si/Fe]) strongly correlates with galaxy luminosity (and hence mass), underscoring the critical role of galaxy mass in shaping chemical evolution. These dwarf galaxies exhibit [Al/Fe$]\sim -0.5$, which is comparable to those of the metal-poor stars in the MW. Additionally, we identified nitrogen-rich field stars in the Fornax dwarf galaxy, which display distinct metallicities compared to its known globular clusters (GCs). If these stars originated in GCs and subsequently escaped, their presence suggests we are observing relics of destroyed GCs, offering possible evidence of cluster disruption.

Among the $\sim 4000$ known pulsars in our Galaxy, $\lesssim 10\%$ are found in globular clusters, but none has been confirmed in any open clusters yet, although they outnumber globular clusters by about 20 times. In this work, we make use of the Gaia DR3 catalog of Galactic open clusters and conduct a pulsar census, in order to identify pulsars that are either 1) current members of open clusters, or 2) escaped from open clusters to the field. Among 164 pulsars with independent distance measurements and 3530 open clusters, we find that 4 pulsars are likely residing in open clusters. In particular, we find compelling evidence that the binary pulsar J1302$-$6350 (B1259$-$63) is a member of the open cluster UBC~525; based on Gaia data, we update its distance to be $2.26\pm 0.07$~kpc and measure the mass of its companion Be star LS 2883 to be $16.8 M_\odot$. For 145 pulsars with both distance and proper motion measurements and 2967 open clusters with full kinematic parameters, we trace the past trajectories of both pulsars and open clusters in the Galactic gravitational potential, and find pulsars that were within 3 times the radius of a cluster. This results in 19 pulsars that were likely born in open clusters. We discuss implications for the formation history of PSR J1302$-$6350 and highlight the scientific potential of searching for pulsars in open clusters.

The China Space Station Telescope (CSST), slated to become China's largest space-based optical telescope in the coming decade, is designed to conduct wide-field sky surveys with high spatial resolution. Among its key observational modes, slitless spectral observation allows simultaneous imaging and spectral data acquisition over a wide field of view, offering significant advantages for astrophysical studies. Currently, the CSST is in the development phase and lacks real observational data. As a result, the development of its data processing pipeline and scientific pre-research must rely on the mock data generated through simulations. This work focuses on developing a simulation framework for the CSST slitless spectral imaging system, analyzing its spectral dispersing properties and structural design. Additionally, the detection performance of the slitless spectral system is assessed for various astrophysical targets. Simulation results demonstrate that nearly all 1st order spectra are accompanied by corresponding 0th order images, facilitating accurate source identification. Furthermore, the GI spectral band exhibits superior detection efficiency compared to the GV and GU bands, establishing it as the primary observational band for stellar and galactic studies. This work successfully develops a simulation framework for the CSST slitless spectroscopic equipment.

Polycyclic Aromatic Hydrocarbons (PAHs) are commonly detected in protoplanetary disks, but it is unclear what causes the wide range of intensities across the samples. In this work, the measured PAH intensities of a range of disks are compared with ALMA dust continuum images, in order to test whether there is evidence that PAHs are frozen out on pebbles in dust traps and only sublimate under certain conditions. A sample is constructed from 26 T Tauri and Herbig disks located within 300 pc, with constraints on the 3.3 $\mu$m PAH intensity and with high-resolution ALMA continuum data. The midplane temperature is derived using a power-law or with radiative transfer modeling. The warm dust mass is computed by integrating the flux within the 30 K radius and convert to a dust mass. A strong correlation with a Pearson coefficient of 0.88+/-0.07 between the 3.3 micron PAH intensity and the warm dust mass was found. The correlation is driven by the combination of deep upper limits and strong detections corresponding to a range of warm dust masses. Possible correlations with other disk properties like FUV radiation field or total dust mass are much weaker. Correlations with PAH features at 6.2, 8.6 and 11.3 micron are potentially weaker, but this could be explained by the smaller sample for which these data were available. The correlation is consistent with the hypothesis that PAHs are generally frozen out on pebbles in disks, and are only revealed in the gas phase if those pebbles have drifted towards warm dust traps inside the 30 K radius and vertically transported upwards to the disk atmosphere with sufficiently high temperature to sublimate PAHs into the gas phase. This is similar to previous findings on complex organic molecules in protoplanetary disks and provides further evidence that the chemical composition of the disk is governed by pebble transport.

The chemistry of planetary atmospheres containing molecular nitrogen as a major atmospheric component is strongly influenced by the reactions of atomic nitrogen. Although nitrogen atoms in their ground electronic state N(4S) are mostly unreactive towards stable molecules, electronically excited nitrogen atoms N(2D) are much more reactive and could play an important role in the formation of nitriles and other nitrogen bearing organic molecules in planetary atmospheres such as Titan. Despite this, few kinetic studies of N(2D) reactions have been performed over the appropriate low temperature range. Here, we report the results of an experimental study of the reactions N(2D) + methylacetylene, CH3CCH, and N(2D) + acetonitrile, CH3CN, using a supersonic flow reactor at selected temperatures between 50 K and 296 K. N(2D) atoms, which were generated indirectly as a product of the C(3P) + NO reaction, were subsequently detected by laser induced fluorescence in the vacuum ultraviolet wavelength region. The measured rate constants are significantly larger than the estimated values in current photochemical models and do not display large variations as a function of temperature. The new rate constants are included in a 1D coupled ion-neutral model of Titans atmosphere to test their influence on the simulated species abundances. In addition, the overall description of both reactions is improved by considering the results of recent experimental and theoretical work examining the product channels of these processes. These simulations indicate that while the N(2D) + CH3CCH reaction has only a limited overall influence on Titans atmospheric chemistry, the N(2D) + CH3CN reaction could lead to the formation of significant relative abundances of cyanomethamine, HNCHCN, in the upper atmosphere.

Stray light significantly influences the detection capabilities of astronomical telescopes. The actual stray-light level during observations depends not only on the telescope's inherent stray-light suppression capability but also on its operational orbit conditions. Accurate estimation of stray-light levels is crucial for assessing image quality and performing realistic scientific simulations. To rapidly estimate stray-light levels under realistic, complex operational conditions, we developed an analytical model tailored to the China Space Station Telescope (CSST). Our model simulates stray-light backgrounds generated by off-field sources such as moonlight, starlight, and earthshine, incorporating the effects of zodiacal light, as well as scattering and ghost images induced by bright in-field stars. The proposed method allows quick and accurate evaluation of stray-light conditions, facilitating both image simulation and observational scheduling.

The turnover at the peak of the Fourier matter power spectrum encodes a fundamental signature of matter-radiation equality in the early Universe. This delivers a potential standard ruler, independent of baryon acoustic oscillations and therefore able to break parameter degeneracies and improve precision. Furthermore, the turnover scale is independent of redshift and clustering bias, allowing for stacking of the signals from redshift bins. In practice, the very large scale of the turnover means that sample variance and systematics are serious impediments to its detection. Detections of the turnover and measurements of its scale have been made in the WiggleZ, eBOSS, Quaia, and DESI surveys. Upcoming surveys should improve the detection significance and reduce errors on the turnover scale. We use MCMC forecasts for turnover detection in a spectroscopic Euclid-like survey and a futuristic MegaMapper-like survey. In addition to the power spectrum, we include the signal from the bispectrum in equilateral configurations. These surveys are forecast to detect the turnover at $\sim\! 6\sigma$ (Euclid-like) and $\sim\! 15\sigma$ (MegaMapper-like), with precision on the turnover scale of $\sim\! 4\%$ and $\sim\! 2\%$. The inclusion of the bispectrum delivers a modest improvement of $\sim\! 10-17\%$ in the constraints on the turnover scale.

Decades-long studies of asymmetric spectral lines in the solar corona suggest mass and energy transport from lower atmospheric layers to the corona. While slow magnetoacoustic waves and plasma flows are recognized as drivers of these spectral line asymmetries, the role of transverse MHD waves remains largely unexplored. Previous simulations have shown that unidirectionally propagating kink waves, in the presence of perpendicular density inhomogeneities, can produce a turbulence-like phenomenon called ``uniturbulence''. However, the spectroscopic signatures of this effect have not been investigated until now. Due to varying Doppler shifts from the plasma elements with different emissions, we expect to observe signatures of both blueward and redward asymmetries. Past instruments like EIS may have missed these signatures due to resolution limitations, but current instruments like DKIST offer a better opportunity for detection. We conducted 3D MHD simulations of transverse waves in a polar plume with density inhomogeneities and performed forward modeling for the Fe XIII emission line at 10749 Å. Our findings show that transverse waves and uniturbulence induce alternating red and blueward asymmetries, with magnitudes reaching up to 20\% of peak intensity and secondary peak velocities between 30 and 40 km s$^{-1}$, remaining under 100 km s$^{-1}$. These asymmetries propagate with the transverse waves, and even at DKIST resolution, similar signatures can be detected. Our study suggests that spectral line asymmetries can serve as a diagnostic tool for detecting transverse wave-induced uniturbulence.

Neutron captures produce the vast majority of abundances of elements heavier than iron in the Universe. Beyond the classical slow (s) and rapid (r) processes, there is observational evidence for neutron-capture processes that operate at neutron densities in between, at different distances from the valley of $\beta$ stability. Here, we review the main properties of the s process within the general context of neutron-capture processes and the nuclear physics input required to investigate it. We describe massive stars and asymptotic giant branch stars as the s-process astrophysical sites and discuss the related physical uncertainties. We also present current observational evidence for the s process and beyond, which ranges from stellar spectroscopic observations to laboratory analysis of meteorites.

Flares and CMEs are known to be the dominating high-energy phenomena on cool stars. Superflares were thoroughly investigated using broadband photometry predominantly from Kepler, K2, and TESS. Here we present a spectroscopic investigation of superflares on the very active spectroscopic binary CC~Eri. We focus on spectroscopic signatures of (super)-flares and line asymmetries with the goal to characterize superflares spectroscopically. In 70 nights of spectroscopic observations obtained at the ESO~1.52m telescope with the Echelle spectrograph PUCHEROS+ hosted by the PLATOSpec consortium we identified 31 flares from which two are superflares already from the deduced g'-band energies. We also find a broad blue-wing asymmetry occurring in the impulsive phase of another superflare which shows great potential to be a prominence eruption. For the second most luminous flare we find the largest number of excess emissions during the impulsive and gradual flare. We identify the flare to be occurring close to the stellar limb which indicates that the flare was even more energetic than derived from its g'-band and spectral line energies. We identify more than sixty spectral lines in the spectral range of 4100 and 7200Å showing excess emission during this flare. We detect continuum enhancements as well as photospheric line fillings during the flare. Generally we find that depending on the flare energy the number of spectral lines revealing excess emission increases, especially for the more energetic superflares. We therefore conclude that superflares are likely scaled-up versions of less energetic normal flares.

We present deep optical imaging of the extremely isolated dwarf galaxy NGC 6789, obtained with the new 2-meter Two-meter Twin Telescope (TTT3) at Teide Observatory. Despite its location in the Local Void, NGC 6789 exhibits surprising recent central star formation equivalent to approximately 4% of its total stellar mass. The origin of the gas necessary for this level of star formation remains unknown. Our data reach surface brightness limits of 29.8, 29.4, and 28.9 mag arcsec$^{-2}$ in the Sloan g, r, and i filters, respectively, and reveal no evidence of tidal features or merger remnants down to $\sim$30 mag arcsec$^{-2}$ (or equivalently, at a radial distance larger than 1.6 kpc). The galaxy's undisturbed outer elliptical morphology suggests that its recent central star formation was likely produced by either in-situ residual gas or by the accretion of external pristine gas not associated with a minor merging activity.

The $\gamma$-ray emitting binary LS I +61 303 exhibits periodic emission across the electromagnetic spectrum, from radio up to the very-high-energy regime. The most prominent features are the three periods $P_1 = 26.5$ d, $P_2 = 26.9$ d, and $P_{\rm long} = 4.6$ years. Occasionally, a fourth period of 26.7 d is also detected. Mathematically, these four periods are interrelated via the interference pattern of a beating. Competing scenarios that seek to determine which of these periods are physical and which are secondary are under debate. The detection of a fifth period, $P_3 = 26.3$ d, was recently claimed. Our aim is to determine which of these periods are intrinsic (likely related to physical processes) and which of these are secondary (resulting from interference). We avoided any assumption about the physical scenario and restricted our analysis to the phenomenology of the radio emission variability. We selected intervals from archival radio data and applied the generalized Lomb-Scargle periodogram. We fit the observational data to generate synthetic data that only contain specific signals. We analyzed these synthetic data to assess the impact of these signals and their interference on the light curves and the periodogram. The two-peaked profile, consisting of $P_1$ and $P_2$, was detected in the periodogram of the actual data for intervals that are significantly shorter than $P_{\rm long}$, provided that these intervals contain a minimum of the long-term modulation. The characteristics of the observational data and their periodogram could only be reproduced with synthetic data if these explicitly included all three periods $P_1$, $P_2$, and $P_{\rm long}$, the residuals being limited by noise. We have found that all three periods, i.e., $P_1$, $P_2$, and $P_{\rm long}$, could correspond to physically real processes occurring in LS I +61 303.

The Fermi Bubbles are gamma-ray structures extending from the center of the Milky Way to +/-50 degree Galactic latitude that were discovered in data obtained by the Fermi/LAT instrument. Their origin and power source remain uncertain. To help address this uncertainty, here we use a template-free reconstruction of ten years of all-sky Fermi/LAT data provided by Platz et al. (2023) to carry out a pixel-by-pixel spectral analysis of the Bubbles. We recover the position-dependent spectral shape and normalization that would be required for parent proton or electron cosmic ray populations to produce the Bubbles' observed gamma-ray spectra. We find that models in which the gamma-ray emission is driven by either hadronic or leptonic processes can explain the data equally well. The cosmic ray population driving the emission must have either broken power-law or exponentially cut-off spectra, with break or cutoff energies that are almost constant with latitude but spectral indices below the break that harden towards the Bubbles' southern tip. For the leptonic channel, reproducing the observed position-dependent gamma-ray spectrum also requires a cosmic ray electron energy density that grows with distance from the Galactic plane and increases towards the edges of the Bubbles. This finding disfavors scenarios for the origin of the Bubbles where a population of cosmic ray electrons is accelerated near the Milky Way center and subsequently advected out to the extremities of the Bubbles.

This study presents a comprehensive system analysis for an instrument onboard the Habitable Worlds Observatory (HWO), designed for high-precision, high-accuracy differential astrometry, with the primary scientific goal to determine the mass of Earth-like planets around the nearest Sun-like stars. The analysis integrates the definition of the mission profile, the instrumental concept architecture, and an error budget that breaks down the key contributors to the sub-micro arcses precision required for a single measurement. A portion of this budget addresses photo-center estimation for both the target and calibration stars used in differential astrometry. Other major contributors are related to instrumental control of systematics in the reconstruction of differential angle measurements from pixel data (focal plane calibration) to on sky line of sight (telescope distortion calibration). End-of-mission astrometry requires multiple observations (typically 100) of the same target distributed over the mission lifetime. We assess the mission profile to estimate the fraction of survey time required for astrometric survey to achieve the science objective. The proposed architecture of the instrument concept is derived from error budget and mission constraints based on a large visible detector array composed of an assembly of multiple CMOS sensor chips resulting in an overall gigapixel focal plane. We evaluate the Technology Readiness Level (TRL) and propose a way forward reaching TRL 5 level for key technologies by the Mission Consolidation Review in 2029.

Pulse profile modelling is a relativistic ray-tracing technique that has provided constraints on parameters, with a focus on mass and radius, of five rotation-powered millisecond pulsars. While the technique can also be applied to accretion-powered millisecond pulsars (AMPs), this requires accounting for the X-rays from the accretion disc and has only been applied to archival data from the Rossi X-ray Timing Explorer. Here, we apply a previously developed neutron star and accretion disc model to the NICER (Neutron star Interior Composition Explorer) data of the 2019 and 2022 outbursts of SAX J1808.4-3658. We find that a single circular hotspot model is insufficient to explain the data. Modelling with two hotspots and an accretion disc model provides better phase-residuals, but a spectral residual at around 1 keV remains. In contrast, we find a good fit with a flexible background approach, replacing the accretion disk. However, the inferred parameters are not robust due to a degeneracy in the origin of the non-pulsed radiation, which can be caused either by the background or a hotspot that is at least partially in view throughout a full rotation. This work represents an important next step in pulse profile modelling of AMPs by analysing NICER data and underlines the need for more accurate accretion disc and hotspot modelling to achieve robust parameter constraints. We expect the inclusion of higher energy and polarimetric data will provide complementary constraints on inclination, hotspot colatitude, and hotspot size, improving the accuracy of pulse profile modelling of AMPs.

Although mass transfer (MT) has been studied primarily in circular binaries, observations show that it also occurs in eccentric systems. We investigate orbital evolution during non-conservative MT in eccentric orbits, a process especially relevant for binaries containing compact objects (COs). We examine four angular momentum loss (AML) modes; Jeans, isotropic re-emission, orbital-AML and $L_2$ mass loss -- the latter is the most efficient AML mode. For fixed AML mode and accretion efficiency, orbital evolution is correlated: orbits either widen while becoming more eccentric, or shrink while circularizing. Jeans mode generally yields orbital widening and eccentricity pumping, whereas $L_2$ mass loss typically leads to orbital shrinkage and eccentricity damping. Isotropic re-emission and orbital-AML show intermediate behavior. Adopting isotropic re-emission, we demonstrate that eccentric MT produces compact binaries that merge via gravitational waves (GW) within a Hubble time, whereas the same systems would instead merge during MT under traditional modeling. We further show that, in eccentric orbits, the gravitational potential at $L_2$ becomes lower than at $L_1$ across large range of mass ratios and eccentricities, naturally linking eccentricity to $L_2$ mass loss. Since interacting binaries containing COs are frequently eccentric, $L_2$ mass loss offers a new robust pathway to orbital tightening during eccentric MT, contributing to the formation rate of GW sources. This model can treat orbital evolution due to conservative and non-conservative MT in arbitrary eccentricities with applications ranging from MT on the main sequence to GW progenitors.

Satellite galaxies that are near to massive primary galaxies in close pairs can have stellar population ages that are more similar to their primaries than expected. This is one way in which close pairs of galaxies show galactic conformity, which is thought to be driven by assembly bias. Such conformity is seen in ages, morphologies and star formation rates in different samples. This paper revisits a high signal-to-noise SDSS spectroscopic sample, by spectral fitting of new stellar population models, to investigate satellite galaxy properties of age, metallicity and alpha-element abundance. We find the clear signature of age conformity, as previously seen, but no clear evidence for conformity in metallicity or abundance ratios. The offsets showing age conformity are not caused by age-metallicity degeneracies. There is a suggestion in these data that lower velocity dispersion satellites have increased [alpha/Fe] compared to a control sample of passive galaxies, however this needs further observations to be verified. Our results also suggest an intriguing turnover in the age trends of the satellites at the highest velocity dispersion, perhaps reflecting the onset of environment-related processes in the most massive groups.

ANTARES, a neutrino detector located in the depths of the Mediterranean Sea, operated successfully for over 15 years before being decommissioned in 2022. The telescope offered an ideal vantage view of the Southern Sky and benefited from optimal water properties for enhanced angular resolution. This study makes use of data collected over the entire operational period of ANTARES to search for sources of high-energy cosmic neutrinos, considering both steady and flaring emission scenarios. First, a time-integrated search for high-energy neutrino clustering across the celestial sphere is conducted. The most significant accumulation is found at coordinates $(\alpha, \delta) =(200.5^\circ\, 17.7^\circ)$ with a post-trial p-value equal to 0.38. A dedicated search in the Galactic Plane is also performed for extended sources, yielding no significant excess. Additionally, a list of potential neutrino sources are investigated. The blazar MG3 J225517+2409 is identified as the most significant object, yet the excess remains compatible with background fluctuations. A mild local excess of 2.4$\sigma$ is found for the blazar TXS 0506+056. The full sky is also examined for the presence of flaring neutrino emissions. The most significant excess in this case corresponds to a $\sim$4-day flare from the direction $(\alpha, \delta) = (141.3^\circ\, 9.8^\circ)$, with a post-trial p-value of 0.30. Finally, the directions of sources highlighted in IceCube's time-dependent searches are investigated. Temporal overlaps between ANTARES and IceCube flares are identified for PKS 1502+106 and TXS 0506+056, with an estimated chance probability of about 0.02%, making this observation particularly noteworthy.

Gravitational waves induced by primordial density perturbations provide a powerful probe of the Universe's thermal history, which may include an early matter-dominated (eMD) era predicted by well-motivated particle-physics models. The induced GWs can be significantly enhanced when the Universe undergoes a sudden transition from an eMD era to an era with pressure, such as a radiation or kination era. This enhancement arises from the growth of density perturbations during the eMD era and their rapid oscillations during the era with pressure. This phenomenon is called the poltergeist mechanism. In this review, we explain the essence of the poltergeist mechanism and explore concrete scenarios in which such an enhancement can occur.

We present a detailed dynamical analysis of the Quaoar-Weywot system based on nearly 20 years of high-precision astrometric data, including new HST observations and stellar occultations. Our study reveals that Weywot's orbit deviates significantly from a purely Keplerian model, requiring the inclusion of Quaoar's non-spherical gravitational field and center-of-body-center-of-light (COB-COL) offsets in our orbit models. We place a robust upper limit on Weywot's orbital eccentricity ($e<0.02$), substantially lower than previous estimates, which has important implications for the strength of mean motion resonances (MMRs) acting on Quaoar's ring system. Under the assumption that Quaoar's rings lie in its equatorial plane, we detect Quaoar's dynamical oblateness, $J_2$, at $\sim$2$\sigma$ confidence. The low $J_2$ value found under that assumption implies Quaoar is differentiated, with a total bulk density of $1751\pm13$ (stat.) kg m$^{-3}$. Additionally, we detect significant COB-COL offsets likely arising from latitudinal albedo variations across Quaoar's surface. These offsets are necessary to achieve a statistically robust orbit fit and highlight the importance of accounting for surface heterogeneity when modeling the orbits of dwarf planet moons. These findings improve our understanding of Quaoar's interior and surface while providing key insights into the stability and confinement mechanisms of its rings.

Recent observations of a stellar occultation have revealed the presence of a previously undiscovered small satellite around Quaoar. Orbiting near Quaoar's unusual ring system, this new satellite has the potential to provide significant insights into the formation and evolution of Quaoar and its ring system. In this letter, we characterize the orbit of this newly discovered satellite, finding that it is likely on a $3.6^{+0.5}_{-0.3}$-day orbit, plausibly placing it near a 5:3 mean motion resonance with Quaoar's outermost known ring. Examining the possibility of observing the newly discovered satellite with further stellar occultations, we estimate that $\sim$hundreds of observing stations are required for recovery, since phase information about its orbit was rapidly lost after the lone detection. We also attempted to recover the satellite in JWST NIRCam imaging of Quaoar, but find no convincing detection. This non-detection is limited by the accuracy of the available NIRCam PSF models, as well as the satellite's extreme faintness and close-in orbital separation. Therefore, current-generation telescopes will likely struggle to directly image this new satellite, but near-future 30-meter-class telescopes should prove capable of detecting it. Discovery of such a satellite provides evidence that the rings around Quaoar may have been part of an initially broad collisional disk that has evolved considerably since its formation. To further explore this hypothesis, we encourage follow-up observations of the rings and satellites with stellar occultations and direct imaging, as well as updated hydrodynamical, collisional, and tidal modeling of the system.

The mass distribution of neutron stars encodes information about their formation and binary evolution. We compare the masses of two distinct populations: I) the recently identified Gaia neutron stars in wide orbits with solar-like companions and, II) the assumed first-born recycled pulsar in Galactic double neutron star systems. Naively, one would expect their masses to differ due to both the presumed differences in their evolutionary histories, as well as astrophysical selection effects that can filter out configurations that would merge or be disrupted. Yet, we find that their mass distributions are strikingly similar. Using a two-component Gaussian model, we find that both populations exhibit a narrow component centred near $1.3 \text{ M}_\odot$, accompanied by a broader, higher-mass component that extends the distribution toward larger masses. The highest density regions of their fitted parameter posteriors coincide by over 91.6%. Statistical tests further confirm the agreement between these distributions with a Jensen-Shannon divergence $JS < 0.08$ and an earth mover's distance of $W <0.063 \text{ M}_\odot$ at 90% credibility. This finding seems to imply that both mass functions reflect the natal mass distribution of first-born neutron stars in binary systems, supporting the hypothesis that neutron stars can be born with high masses. Consequently and perhaps surprisingly, binary evolutionary processes need not impart features on the NS mass distribution.

The accurate positional measurement of Supernova (SN) 1987A is important for determining the kick velocity of its compact object and the velocities of the ejecta and various shock components. In this work, we perform absolute astrometry to determine the position of SN 1987A. We used multi-epoch Hubble Space Telescope imaging to model the early ejecta and the equatorial ring (ER). We combined our measurements and obtained the celestial coordinates in the International Celestial Reference System (ICRS) by registering the observations onto Gaia Data Release 3. The final average position of the different measurements is ${\alpha = 5^{\mathrm{h}}~ 35^{\rm{m}}~ 27^{\rm{s}}.9884(30)}$, ${\delta = -69^{\circ}~ 16'~ 11''.1134(136)}$ (ICRS J2016). The early ejecta position is located 14 mas south and 16 mas east of the ER center, with the offset being significant at 96% confidence. The offset may be due to instrument and/or filter-dependent systematics and registration uncertainties, though an intrinsic explosion offset relative to the ER remains possible. Image registration with proper motion corrections yields similar astrometry and a source proper motion of ${\mu_{\rm east} (\equiv \rm{PM_{\alpha }*}) = 1.60 \pm 0.15 ~\rm{mas ~ yr^{-1}}}$ and ${\mu_{\rm{north}} (\equiv \rm{PM_{\delta}}) = 0.44 \pm 0.09~\rm{mas ~ yr^{-1}}}$, in agreement with the typical local motion of the Large Magellanic Cloud. The absolute positional uncertainty of 21 mas adds a systematic uncertainty to the sky-plane kick velocity of ${123}~(t/40~\rm{yr})^{-1}~\rm{km~s}^{-1}$, where $t$ is the time since the explosion. Comparing the location of the compact source observed with JWST to our updated position implies a sky-plane kick of ${399\pm148~\mathrm{km~s^{-1}}}$ and a 3D kick of ${472\pm126~\mathrm{km~s^{-1}}}$, which is consistent with previous estimates.

We examine the claimed observations of a gravitational external field effect (EFE) reported in Chae et al. We show that observations suggestive of the EFE can be interpreted without violating Einstein's equivalence principle, namely from known correlations between morphology, environment and dynamics of galaxies. While Chae et al's analysis provides a valuable attempt at a clear test of Modified Newtonian Dynamics, an evidently important topic, a re-analysis of the observational data does not permit us to confidently assess the presence of an EFE or to distinguish this interpretation from that proposed in this article.

We present a symmetry-protected supergravity realization of hybrid $\alpha$-attractor inflation with a constant sequestered uplift. The model achieves an exact analytic embedding of the attractor geometry while maintaining vacuum stability and radiative control. The uplift, generated by a hidden Stückelberg $U(1)_D$ sector, preserves the inflaton dynamics and provides an independent handle on the post-inflationary vacuum energy. The framework yields precise next-to-leading-order predictions for the scalar spectral tilt and tensor amplitude, fully consistent with current ACT DR6, DESI DR2, and Planck data. Radiative and geometric corrections remain exponentially suppressed, ensuring the robustness of the inflationary trajectory. This construction offers a minimal, UV-complete, and testable benchmark for embedding $\alpha$-attractor inflation in supergravity, with tensor modes potentially observable by LiteBIRD and CMB-S4.

We derive a relativistic extension of Modified Newtonian Dynamics (MOND) within the framework of entropic gravity by introducing temperature-dependent corrections to the equipartition law on a holographic screen. Starting from a Debye-like modification of the surface degrees of freedom and employing the Unruh relation between acceleration and temperature, we obtain modified Einstein equations in which the geometric sector acquires explicit thermal corrections. Solving these equations for a static, spherically symmetric spacetime in the weak-field, low-temperature regime yields a corrected metric that smoothly approaches Minkowski space at large radii and naturally contains a characteristic acceleration scale. In the very-low-acceleration regime, the model reproduces MOND-like deviations from Newtonian dynamics while providing a relativistic underpinning for that phenomenology. We confront the theory with rotation-curve data for NGC~3198 and perform a Bayesian parameter inference, comparing our relativistic MOND (RMOND) model with both a baryons-only Newtonian model and a dark-matter halo model. We find that RMOND and the dark-matter model both fit the data significantly better than the baryons-only Newtonian prediction, and that RMOND provides particularly improved agreement at $r\gtrsim 20\,\mathrm{kpc}$. These results suggest that temperature-corrected entropic gravity provides a viable relativistic framework for MOND phenomenology, motivating further observational tests, including gravitational lensing and extended galaxy samples.

Following the recent Atacama Cosmology Telescope (ACT) results, we revisit chaotic inflation based on a single complex scalar field with mass term $M^2 |\Phi|^2$, which usually predicts a spectra index $n_s\approx 0.96$ but a too-large tensor to scalar ratio $r\approx 0.16$. With radiative corrections, the potential $M^2 |\Phi|^2 \ln \left( |\Phi|^2/\Lambda^2 \right)$ induces spontaneous symmetry breaking near the scale $\Lambda$, yielding a Pseudo Nambu-Goldstone boson which can play the role of a quintessence field, hence radiative inflation and dark energy (RIDE). Including a non-minimal coupling to gravity $\xi |\Phi|^2 R^2$ reduces $r$, allowing a good fit of the RIDE model to Planck data. Allowing a small additional quartic coupling correction $\lambda |\Phi|^4$ increases both $n_s$ and $r$, with a good fit to ACT data sets achieved for $\xi \approx 1$.

The seminal work of Coleman, Glaser, and Martin established that, at zero temperature, any non-trivial solution to the equations of motion with the least Euclidean action is $O(D)$-symmetric. This paper extends their foundational analysis to finite temperature. We rigorously prove that for a broad class of scalar potentials, any saddle-point configuration with the least action is necessarily $O(D\!-\!1)$-symmetric and monotonic in the spatial directions. This result provides a firm mathematical justification for the symmetry properties widely assumed in studies of thermal vacuum decay and cosmological phase transitions.

The discovery of the accelerated expansion of the universe highlighted General Relativity's inability to naturally account for dark energy without invoking a finely tuned cosmological constant. In response, a wide range of alternative paradigms have been proposed. Among these, Teleparallel Gravity and Symmetric Teleparallel Gravity, which depart from the Riemannian framework of General Relativity and instead rely on torsion or non-metricity to describe gravitational interactions, have gained increasing attention in recent years. We explore extensions of these non-Riemannian approaches, aiming to replicate the observed late-time acceleration of the universe by emulating the cosmological constant's role. We also evaluate the consistency of these theories with local gravity constraints by studying their static, spherically symmetric solutions. We show that although some models can reproduce the desired cosmological behavior, they often fail to meet Solar System observational bounds, particularly through deviations in the predicted Eddington parameter. Our findings underscore the need for a unified approach that tests modified gravity theories across both cosmological and local scales.

It would be reasonable to recall some critical issues in physical cosmology development. GR was created by A. Einstein in 1915. In 1917 Einstein proposed the first (static) cosmological model. Soon after the A. Eddington proved that the model is unstable therefore it can not be realizable in nature. In 1922 and 1924 A. A. Friedmann found non-stationary solutions for cosmological equations written in the framework of GR. In 1927 G. Lemaitre obtained very similar results and, in addition, he derived the Hubble law (E. Hubble obtained this law from observations). Unfortunately, G. Lemaitre published his paper in not very popular Belgium journal. In 1931 Lemaitre proposed the first version of hot Universe model (he called it hypothesis of the primeval atom). In his book Lemaitre predicted even a background radiation as a signature of his model. One of the important property of the Lemaitre -- Gamow model was a prediction of CMB radiation with a temperature around a few K. It was recalled that the discovery of CMB radiation was done by T. Shmaonov in 1956 and his paper was published in 1957 (several years before Penzias and Wilson). In 1965, 1970 E. B. Gliner proposed vacuum like equation of matter which could correspond to exponential explosion of the Universe which was later called inflation. For decades in USSR, Friedmann's cosmological non-stationary models were treated as purely mathematical results without cosmologocal applications. On September 16, 1925 passed away untimely and it would be reasonable to remind today his great contribution in physical cosmology since the authors of book on Friedmann wrote that "similarly to Copernicus who forced the Earth to move Friedmann forced the Universe to expand".

The interdisciplinary field of astrochemistry arose during the 1970s as observations in previously unexplored parts of the electromagnetic spectrum began to reveal the extent of a molecular component of interstellar matter with a surprisingly rich chemistry. Astrochemistry expanded further in order to explain the role of atomic and molecular processes in a broad range of phenomena in the universe. It is instructive to describe the current scope of astrochemistry using the career and accomplishments of Alexander Dalgarno as an organizing principle. Dalgarno helped to establish a self-sustaining community of astrochemists around the world. His own research interests highlight the early development of astrochemistry and anticipate much of its later evolution. His theoretical investigations of fundamental atomic and molecular processes lie at the heart of the subject.

We show that the stochastic background of gravitational wave memory of growing type leads to a fractional Brownian motion increasing at the order of $t^{H}$ for large $t$ where $\frac{1}{2} < H <1$. This beats the scaling law of Brownian motion. In this article we investigate sources of gravitational waves in the early universe as well as in astrophysical settings. Cosmological sources may include primordial black holes or other sources immediately after the Big Bang when there were pockets of hot material, and large density fluctuations. Gravitational waves from mergers of primordial black holes produce memory. We show that due to the conditions in which these are taking place the gravitational wave memory will be increasing in time following a certain power law. Corresponding results hold for any gravitational wave memory from a cosmological source where the surrounding conditions are similar. The stochastic limit of these memories is a stochastic process growing in time faster than the $\sqrt{t}$ scaling law of Brownian motion. The latter is also typical for noise and for the limit of memory events as they have been mostly considered in the literature. In an expanding universe, the memory is enhanced by the expansion itself. Our results provide a tool to extract gravitational wave sources of this type from data using this memory signature. This would be particularly useful for the PTA data that has been already observed, answering the long-standing question on how to extract memory signals from the data. Further, the new results open up a new door to explore the conditions right after the Big Bang using the long-range dependence and further probability analysis.

Gravitational waves (GWs) can be distorted by intervening mass distributions while propagating, leading to frequency-dependent modulations that imprint a distinct signature on the observed waveforms. Bayesian inference for GW lensing with conventional sampling methods is costly, and the problem is exacerbated by the rapidly growing GW catalog. Moreover, assessing the statistical significance of lensed candidates requires thousands, if not millions, of simulations to estimate the background from noise fluctuations and waveform systematics, which is infeasible with standard samplers. We present a novel method, \texttt{DINGO-lensing}, for performing inference on lensed GWs, extending the neural posterior estimation framework \texttt{DINGO}. By comparing our results with those using conventional samplers, we show that the compute time of parameter estimation of lensed GWs can be reduced from weeks to seconds, while preserving accuracy both in the posterior distributions and the evidence ratios. We train our neural networks with LIGO detector noise at design sensitivity and a lens model that accommodates two overlapping chirps with opposite parity. We show that the lensing parameters are recovered with millisecond precision for the time delays. We also demonstrate that our network can identify signals diffracted by point masses, highlighting its flexibility for searches. By simulating thousands of lensed and nonlensed events, we determine how the detectability changes with different source properties. \texttt{DINGO-lensing} provides a scalable and efficient avenue for identifying and characterizing gravitationally lensed GW events in the upcoming observing runs.

The Parity-Doublet Model (PDM) is a chirally invariant effective theory for strong-interaction matter involving nucleons and their opposite-parity partners in a parity-doubling framework. We introduce a multiplicatively renormalizable mean-field approach to include the baryonic vacuum contributions to the resulting grand-canonical potential in an explicitly renormalization-group invariant form. As an application, we evaluate the pertinent thermodynamics of two-flavor symmetric and asymmetric nuclear matter, focusing on the restoration of spontaneously broken chiral symmetry at baryon densities and temperatures relevant for the astrophysics of neutron stars. Special attention is paid to the effect of the baryonic vacuum fluctuations on the evolution of chiral condensate with baryon density and temperature for specific choices of the chirally invariant baryon mass $m_0$ to demonstrate the importance of consistently including these vacuum fluctuations in the PDM.

Bayesian inference requires determining the posterior distribution, a task that becomes particularly challenging when the dimension of the parameter space is large and unknown. This limitation arises in many physics problems, such as Mixture Models (MM) with an unknown number of components or the inference of overlapping signals in noisy data, as in the Laser Interferometer Space Antenna (LISA) Global Fit problem. Traditional approaches, such as product-space methods or Reversible-Jump Markov Chain Monte Carlo (RJMCMC), often face efficiency and convergence limitations. This paper presents samsara, a Continuous-Time Markov Chain Monte Carlo (CTMCMC) framework that models parameter evolution through Poisson-driven birth, death, and mutation processes. samsara is designed to sample models of unknown dimensionality. By requiring detailed balance through adaptive rate definitions, CTMCMC achieves automatic acceptance of trans-dimensional moves and high sampling efficiency. The code features waiting time weighted estimators, optimized memory storage, and a modular design for easy customization. We validate samsara on three benchmark problems: an analytic trans-dimensional distribution, joint inference of sine waves and Lorentzians in time series, and a Gaussian MM with an unknown number of components. In all cases, the code shows excellent agreement with analytical and Nested Sampling results. All these features push samsara as a powerful alternative to RJMCMC for large- and variable-dimensional Bayesian inference problems.