ALT We apply positive-unlabelled (PU) machine learning to the 1623 blazars of uncertain type (BCUs) in the Fermi Large Area Telescope Fourth Source Catalogue, Data Release 4 (4FGL-DR4). Five PU classifiers are trained on seven gamma-ray features, once with the 820 flat-spectrum radio quasars (FSRQs) and once with the 1490 BL Lac objects as the labelled class (FSRQ mode and BL Lac mode). Each source is scored out of fold over 100 repeated five-fold splits, and its confidence is the fraction of splits in which at least three of the five classifiers flag it. At a confidence of at least 0.1, 437 BCUs are FSRQ-like, 597 are BL Lac-like, 12 are flagged in both modes and 577 in neither. On known sources the ensemble reaches a recall of 0.80 in FSRQ mode and 0.82 in BL Lac mode at a false-positive rate of 0.08, but a logistic regression trained on the labelled sources alone does at least as well, so PU learning gives no accuracy gain here. Removing the sky coordinates from the features does not lo

ALT X-ray images of supernova remnants provide important information regarding the spatial distribution of the physical and chemical parameters of the shocked plasma. Our objective is to provide a comprehensive and quantitative assessment of the similarities observed across narrow-band images and equivalent-width maps of a given supernova remnant. We also aim to perform comparative analyses between distinct remnants. We adopted two dendrogram-based techniques, namely a multivariate analysis and a deep-learning, graph-based approach (by exploring different metrics) for the study of Chandra X-ray maps of Cassiopeia A, G292.0+1.8, Tycho's SNR, Kepler's SNR, and W49B. We also tested the reliability of our results on synthetic X-ray maps produced from a 3D hydrodynamic simulation of Cassiopeia A. We identify clusters of narrow-band images (and equivalent-width maps) corresponding to emission lines of chemical elements that are expected to be synthesized in the same layers of the exploding star

ALT Models for X-ray spectroscopy involving complex relativistic or plasma physics are commonly pre-computed on a grid, In this paper, we aim to quantify the potential biases and distortions introduced by the computational error and propagated into parameter inference by interpolating linearly these complex, non-linear models. We analyse the performance of Bayesian sampling algorithms on mock inference problems. Then, we model real observations of an accreting black hole X-ray binary in both the soft and hard states. We find that linear interpolation can a) greatly bias the posterior distribution of model parameters and b) distort the likelihood space to such a degree that posterior distributions become artificially multimodal. This multi-modality causes a noticeable loss in computational efficiency in both sampling and fitting techniques. As a result, exploring a given parameter space until convergence requires an extremely large computational cost. These findings call for improving the c

ALT In canonical twisted-torus models of hydromagnetic equilibrium in neutron stars, the toroidal field is confined to regions where the poloidal field lines are closed. As spindown torques applied at the stellar surface need not be communicated efficiently to such magnetically-unlocked regions, toroidal zones or magnetic voids may rotate faster than the electromagnetically braked part of the star. Continuous gravitational radiation from the associated non-corotating quadrupole may therefore be emitted at higher frequencies than poloidal ones to a degree that depends on the diffusive microphysics controlling angular momentum transport. Dissipative processes can suppress long-lived lags, and we estimate the relevant timescales and their sensitivity to microphysics. Nevertheless, we show that a quadrupole component whose pattern speed differs from the observed spin is shifted, or smeared, over a finite frequency band. Single-template or narrowband upper limits therefore constrain only the qu

ALT Fast radio bursts (FRBs) show diverse temporal morphologies, shaped both by their intrinsic emission and by propagation effects such as residual dispersion and multipath scattering. Because several of these effects can broaden a burst asymmetrically, an asymmetric profile does not by itself establish multipath scattering. We measure the frequency dependence of the temporal tail in FRB 20210415C, a bright burst from the repeating source FRB 20210219C. The burst is detected across approximately 400-800 MHz. Frequency-resolved fits yield an empirical exponential-tail timescale, τₑₘₚ, that follows τₑₘₚproptoνᵅ. Two complementary treatments of the underlying pulse width give α=-3.95±0.07 and -4.14±0.08. Both results are consistent with the commonly adopted ν⁻⁴ scattering law. The inferred scattering time is approximately 8.0 ms at 583 MHz, exceeding Galactic foreground estimates by a factor of at least 4×10². This favours a dominant contribution beyond the Milky Way, although the data do no

ALT Extragalactic fast X-ray transients (EFXTs) detected by the Einstein Probe are extending the parameter space of relativistic stellar explosions toward softer and longer-lived transients. Here we report EP251129a/GRB 251129A at z=0.505, which exhibits two X-ray plateaus: an early plateau lasting ∼ 10⁴ s followed by a rapid decay with spectral softening, and a second plateau extending to 60 days, placing it at the extreme long-duration end of Gamma Ray Burst (GRB) plateaus. The early optical emission evolves independently of the X-ray, indicating a different origin; whereas the unusual radio afterglow shows a rapid rise of Fν∝ t¹.⁹⁻².⁵ and a delayed peak at ∼36-40 days, providing strong evidence for an off-axis geometry. We find that the early X-ray behavior resembles those of ultra-long GRBs (ULGRBs) and can be naturally explained by the internal dissipation from a newborn millisecond magnetar undergoing gravitational-wave-dominated spin-down before collapsing into a black hole. The ear

ALT Electron-capture supernovae (ECSNe) arise from a narrow progenitor parameter space between oxygen-neon white dwarf formation and iron-core collapse supernovae, governed by the competition between core growth and envelope removal. Binary interactions modify this balance through mass transfer and mergers. Using the binary population synthesis framework POSYDON, we model ECSN progenitors across metallicities from Z/Z⊙=2 to 10⁻⁴, focusing on the initial parameter space, pre-supernova stripping, envelope-based classification, surviving companions, post-supernova orbits, and cosmic event rates. The lower edge of the binary ECSN initial primary mass lies near 7 M⊙, owing to efficient convective overshooting in the POSYDON grids, whereas the upper edge increases with metallicity because stronger line-driven winds require larger initial masses to build carbon-oxygen cores within the ECSN range. Stable mass transfer and mergers occupy distinct regions in initial mass ratio and orbital period spa

ALT We aim to derive an analytical prescription for the line-of-sight-integrated particle distribution around moving pulsars, suitable for constructing spatial templates of the associated TeV-halo gamma-ray emission without resorting to computationally expensive numerical integrations. We consider electrons and positrons continuously injected by a moving source, undergoing isotropic diffusion and radiative energy losses. Assuming spatially uniform target photon fields, as appropriate for the cosmic microwave background and approximately valid for the interstellar radiation fields, the projected particle distribution provides a useful proxy for the inverse-Compton gamma-ray morphology. We show that the line-of-sight integration of the particle distribution can be performed exactly, reducing the calculation to a single numerical integral over the injection history. Under the additional assumptions of constant injection luminosity and a simplified treatment of energy losses, we derive a fully

ALT We present a high-resolution XRISM/Resolve observation of the persistent black hole candidate 4U 1957+115, revealing the first detection of an intrinsic disk wind in this source. The absorption is dominated by highly ionized Fe XXV and Fe XXVI and varies substantially throughout the observation, becoming prominent during the final ∼40 ks despite a modest decrease of only ∼5–10% in source flux. The observed evolution of the absorption cannot be explained solely by ionization changes driven by the modest continuum variability, favoring an inhomogeneous outflow with evolving line-of-sight properties. Time-resolved spectroscopy reveals substantially narrower absorption features in shorter intervals, with the inferred turbulent velocity decreasing from ∼350 km/s in the longer integration to ≲70 km/s in the shortest selections. This suggests that the broader absorption profiles measured over longer integrations may result, at least in part, from averaging over an evolving wind rather than fr

ALT The eROSITA telescope array aboard the joint German–Russian Spektrum-Roentgen-Gamma (SRG) mission delivered the deepest soft all-sky X-ray survey to date, scanning the entire sky more than four times between December 2019 and February 2022. The potential of the survey remains, however, hampered by the fact that only data for the half of the sky owned by the German consortium have been released publicly, whereas the other half remains accessible only to the Russian consortium, effectively making eROSITA a "half-sky" survey for most applications. The only publicly accessible all-sky "data product" as of 2026 is a single press-release image published in June 2020 jointly by both consortia to celebrate the completion of the first all-sky survey (eRASS1). Here I present the first all-sky eROSITA catalogue based on this image, containing around 63 thousand sources with an estimated completeness of about 50% above 3×10⁻¹³ erg cm⁻² s⁻¹ in the 0.2-2.3 keV band and a positional accuracy of ∼1 ar

ALT EP241021a is a peculiar fast X-ray transient exhibiting a long X-ray plateau and an optical rebrightening, both challenging the traditional jet afterglow model. Whether its nature is a stellar explosion or a tidal disruption event (TDE) remains debated. Here we present late-time HST/WFC3 and Gemini-N/GMOS observations of its host galaxy at z=0.748. After ∼300 days post-trigger, the transient emission had faded below detection, revealing a dwarf disk galaxy with an effective radius Rₑ=1.7 kpc, a stellar mass M⋆∼3×10⁸M⊙, and a high star formation rate of ∼5 M⊙{ yr⁻¹}. Combined with previous very long baseline interferometry measurements, the transient can be located in the galactic disk with a projected physical offset of 0.95±0.13 kpc from the galaxy center. Host-subtracted optical light curves show that the rebrightening ceased at ∼47 days, followed by a sudden drop with a power-law index steeper than -3.3, coincident with a similar drop in the X-ray light curve. This synchronous drop

ALT Binary interaction can substantially alter massive-star evolution and pre-supernova structure, changing core-collapse outcomes and nucleosynthetic yields. We compare explodability and nucleosynthesis in 66 non-rotating, solar-metallicity single-star and binary-stripped progenitors spanning zero-age main-sequence (ZAMS) masses of 11-45 M⊙, using the spherically symmetric PUSH framework and nucleosynthesis post-processing. Both populations explode up to 22 M⊙, with binary stripping altering explodability at higher ZAMS masses. Successful explosions span similar energies (∼0.4-1.3 B) and remnant masses (∼1.4-2.0 M⊙). The largest nucleosynthetic differences occur at low ZAMS masses, particularly for material undergoing explosive O and Si burning. The ⁵⁶Ni yields and iron-group abundances broadly agree with observations of core-collapse supernovae and the metal-poor star HD 84937. When compared with calculations using time-dependent mixing-length theory and a two-parameter explodability cri

ALT We construct new finite-temperature, composition-dependent equation of state (EOS) tables for astrophysical simulations by implementing a recently developed energy-density functional. The functional is constrained by ab initio nuclear matter calculations and neutron-star observations. A distinguishing feature of this functional is a non-monotonic density dependence of the nucleon effective mass, with an increase beyond saturation density. Using these EOS tables, we investigate the impact of current uncertainties in nuclear matter properties on core-collapse supernova (CCSN) evolution with spherically symmetric simulations employing an effective treatment of convective mixing. The magnitude of the EOS effects depends on the progenitor compactness. Within current constraints, variations in incompressibility, symmetry energy, and high-density pressure produce only modest differences during the early post-bounce evolution. In contrast, the effective mass dependence has a much stronger infl

ALT High-energy outbursts from magnetars may be associated with crustal failures or quakes. The magnetoelastic modes of the star can be excited to large amplitudes in such a framework, providing a natural explanation for the quasi-periodic oscillations observed in the X-ray tails of some events. However, previous calculations of torsional modes have been carried out assuming an intact crust without accounting for the failure itself. We develop a code in this paper that solves the axial sector of the linearised Einstein-Maxwell-Euler equations in a cavity that hosts inelastic regions or 'plastic islands'. As crustal elements are displaced, shear stresses are tracked as a function of time to allow cells to dynamically switch from elastic to inelastic states. The presence of islands in the crust promotes phase mixing and, when reflected waves mix constructively, large sections fail collectively ('avalanche') if the initial kick is strong enough. Transient spectral features are observed as a r

ALT Synchrotron polarization is a powerful tool for diagnosing magnetohydrodynamic (MHD) turbulence, yet prior analyses are confined to the optically thin regime, neglecting the effects of synchrotron self-absorption (SSA). Here, we incorporate SSA into the radiative transfer of polarized synchrotron emission and employ 3D MHD turbulence simulations to investigate its impacts on polarization statistics. We show that SSA strongly modulates polarized intensity by suppressing its emission amplitude, steepening its low-frequency power-law slopes, and reducing scale-dependent anisotropy. Notably, SSA does not impede the recovery of the scaling slope of the magnetic turbulence. Our results extend the applicability of synchrotron polarization diagnostics to optically thick astrophysical environments, providing a theoretical foundation for interpreting multi-frequency radio polarization observations. This confirms that polarization statistical techniques remain effective for diagnosing MHD turbule

ALT Radiatively inefficient accretion flows (RIAFs) in low-luminosity active galactic nuclei (LLAGNs) are promising candidates for the PeV astrophysical diffuse neutrino background (DNB), but how the magnetically arrested disk (MAD) state affects their neutrino output and what fraction of LLAGNs are in this state remain unclear. We present a comprehensive study of diffuse neutrino emission from the inner accretion flows of LLAGNs in the MAD state, including all three flavors and both hadronuclear (pp) and photohadronic (pγ) production channels. Assuming that ∼ 5% of the accretion power is transferred to nonthermal protons, current IceCube data allow at most 2.3×10⁻³ of LLAGNs to have their inner accretion flows in a MAD state that can produce high-energy neutrinos. A lower fraction of the accretion power transferred to nonthermal protons would allow a proportionally larger fraction of such LLAGNs. Assuming that the comoving number density of low-excitation radio galaxies (LERGs) approximat

ALT Fast outflows are commonly observed in accreting black hole systems, yet their launching mechanism remains debated, especially when the gas is highly ionized and radiation line driving becomes inefficient. We investigate magnetically driven outflows from magnetically arrested discs (MADs) using a steady, axisymmetric magnetocentrifugal outflow model. The outflow equations follow the classical trans-magnetosonic MHD framework, while the disc structural scalings and outflow-base conditions are motivated by general relativistic magnetohydrodynamics (GRMHD) simulations. We solve for the trans-magnetosonic outflow solutions along prescribed large-scale poloidal magnetic field lines. The outflows launched from the inner disc are strongly accelerated and the formal Newtonian solutions can enter the mildly relativistic regime. The outflow velocity decreases systematically with increasing footpoint radius, producing a radially stratified outflow in which inner streamlines reach UFO-like velocit

ALT We present the discovery of supernova (SN) Ares, a strongly lensed supernova at z_spec=1.276±0.002 in a massive, triply imaged host galaxy behind the MACS J0308.9+2645 galaxy cluster. JWST/NIRSpec spectroscopy spanning the rest-frame optical to NIR of Ares reveals helium features at 5876 Å, 7065 Å, and 10830 Å, as well as Hα and Paβ. A comparison to local core-collapse SN spectra and light curves leads to a classification of SN Ares as a Type IIb supernova, the highest-redshift member of its class spectroscopically identified. A comparison to local SN IIb light curves provides a phase estimate for the spectrum of 34₋₉⁺¹⁰ rest-frame days post-radioactive peak, providing a unique view into a high-redshift stripped-envelope supernova in its late-photospheric evolution. A lens model of the cluster constructed using recent JWST data indicates that SN Ares is the first image to arrive and will reappear in two future images near the center of the cluster plane in ≳ 70 years, with predicted ma

ALT The mass and spin distributions of merging binary black holes offer clues to their formation pathways, which remain uncertain. In this work, we model the population of binary black holes using generic subpopulations with distinct mass-ratio, spin-magnitude, and spin-tilt distributions, whose relative contributions vary with primary mass. Using the 259 binary black holes in the fifth LIGO-Virgo-KAGRA catalog (GWTC-5), we resolve three subpopulations with low, medium, and high spins. The low-spin population dominates for primary masses near 35 M_odot, contributes roughly half of the binaries for primary masses of 10 M_odot, and favors nearly equal mass ratios overall; its spins are consistent with both black holes having negligible spin, with a log Bayes factor of log₁0B=6.1⁺⁰.²₋₀.₃ in favor of vanishing spins. The medium-spin population accounts for the other half of the population around primary masses of 10 M_odot and favors spin magnitudes χ_i ≈ 0.2 for both components, preferentiall

ALT We present a multiwavelength study of GRB 260924A at z=3.51±0.10 using Fermi, Swift, and ground-based optical and near-infrared observations. Its isotropic-equivalent gamma-ray energy, Eγ,ᵢₛₒ≃9.79×10⁵⁴ erg, places it among the most energetic GRBs observed. The prompt emission comprised two bright episodes separated by weaker activity. The X-ray afterglow ranked among the most luminous in our comparison sample at selected post-flare epochs, with a luminosity comparable to that of GRB 221009A at a rest-frame time of 3.5 ks. At a common redshift of z=1, the optical afterglow outshone GRB 221009A by approximately 2 mag at 0.3 d and 1 mag near 1 d. LAT emission extended to approximately 1100 s and showed an early excess above the subsequent decay. The highest-energy photon, 43.3 GeV, arrived at 82 s during the first episode; a 14.2 GeV photon arrived at 304 s between episodes. We describe the afterglow light curves through forward-shock synchrotron and synchrotron self-Compton (SSC) emissio