ALT Optical polarization can be an important probe of particle acceleration and high-energy emission processes in relativistic jets from supermassive black holes. We combined publicly available observations from three past blazar monitoring programs to produce densely sampled light curves for 15 blazars in order to explore the relation of gamma-ray activity to the polarization variability as well as discover new rotations of the polarization angle. We find that the polarization degree does not correlate with the gamma-ray flux for individual sources nor different subsamples of blazars, potentially indicating multiple emission mechanisms. In the combined dataset, we identified a total of 64 rotations in 12 sources, 39 of which are newly identified rotations. We confirm the trend found in previous works for the whole sample: lower polarization degrees during periods of polarization angle rotations. However, looking at the individual sources, we identified cases where the rotation and non-rot

ALT Neural posterior estimation (NPE) gives X-ray spectral fits a posterior in milliseconds instead of the minutes nested sampling costs, but without its calibration guarantee or goodness-of-fit. The simulation-based inference (SBI) literature has trust diagnostics for this gap that have not been benchmarked on X-ray spectra. We provide the first such benchmark on one real XMM-Newton EPIC-pn response: a 5-parameter absorbed continuum across three count regimes ( 100, 1000, 10000 counts), four misspecification families, and nested sampling on the exact Poisson likelihood as reference. A posterior-predictive check catches an unmodeled 6.4 keV line (ROC AUC 0.97 above 1000 counts), where a missed line biases the photon index by 0.20 at bright counts. A 3% detector gain shift stays at chance (AUC 0.50, 36 cells) for all three per-spectrum scores while distorting the continuum; only nested sampling's evidence flags it (Delta log Z -7.8 at medium counts). Separately, one flow passed every recov

ALT The strongest constraints on the velocity-dependent (p-wave) annihilation of weakly interacting massive particle (WIMP) dark matter were derived from the deep potential wells of galaxy clusters. Even weaker signals can be extracted from sufficient aggregated clusters, by cross-correlating γ-rays with large-scale structure tracers or stacking over extensive cluster catalogs. Three independent such analyses show a similar triad of emission lines in Fermi-LAT data, around 70, 40, and 13 GeV, emerging from featureless spectra in wide-sky regions upon cross-correlation with eROSITA maps, and in stacked MCXC, eROSITA, and DESI catalog clusters once boosted to the cluster frame. These lines fit the anticipated χχ→γγ, γZ, and γh annihilation channels of a \sim70 GeV WIMP χ, detected by composite matched filters at trial-corrected global Z-scores reaching 5.6σ (cross-correlations) and 2.3σ (stacking), with intrinsic \sim10^[-20,-19] cm³ s^-1 channel cross-sections. High-resolution spectra estab

ALT We present a population-level spectral analysis of fast radio bursts from the second CHIME/FRB catalog using three curvature-radiation-motivated templates: point-source, one-dimensional bunch, and paired-bunch cavity models. Fits are evaluated with reduced chi-squared χ²ᵣ, AIC/BIC, and the Ljung-Box residual autocorrelation test. All three templates yield median χ²ᵣ values close to unity for both repeating and non-repeating bursts. Repeaters show narrower χ²ᵣ distributions than non-repeaters, with statistically significant but modest population-level differences. AIC favours the one-dimensional bunch model for the largest fraction of sources, whereas BIC increases the relative preference for the simpler point-source model. However, residual autocorrelation remains widespread across all models: only 15%-21% of sources simultaneously satisfy goodness-of-fit and residual-independence criteria, indicating persistent structured residuals beyond the tested templates. These results suggest th

ALT Polarization signatures provide a new window to investigate the effects of radiative cooling in the horizon-scale accretion flows. Morphology and variability of polarization offer quantifiable diagnostics of how cooling modifies the polarised emission from two-temperature GRMHD simulations. We find that cooling enhances the effective Faraday depth, leading to stronger large-scale Faraday scrambling, particularly at higher accretion rates. In contrast, depolarization associated with higher-order photons is comparable between cooling and non-cooling models. Radiative cooling also increases the intrinsic asymmetry in both the ring structure and the polarization pattern. This effect is quantified by enhanced power in non-axisymmetric azimuthal modes (βₘ, m ≠ 2) relative to the dominant quadrupolar component β₂. The increased asymmetry is directly linked to stronger temporal variability of the polarization angle angleβ₂, including frequent sign reversals that are absent in non-cooling model

ALT Context. Accreting X-ray pulsars exhibit strong luminosity-dependent changes in their broad-band spectra. At high luminosities, their spectra are usually described by a power-law continuum with a high-energy cutoff, whereas low-luminosity observations have revealed a two-hump spectral morphology. Aims. We aim to trace the luminosity-dependent spectral evolution of the Be/X-ray pulsar 1A 1118-61 and to constrain the luminosity range over which the high-energy hump becomes clearly distinguishable. Methods. We use dense SRG/ART-XC and Insight-HXMT monitoring, together with three broad-band NuSTAR observations of 1A 1118-61 obtained during its 2026 outburst, to trace the luminosity-dependent evolution of the spectral shape. The ART-XC data follow the decay from a peak luminosity of ≃7×10³⁷ erg s⁻¹ to a low-luminosity plateau at ≃(3-8)×10³⁵ erg s⁻¹ in the 4-35 keV band, while the NuSTAR observations provide broad-band spectra during the bright phase, the decline, and the plateau. We describ

ALT We report large day-timescale variations in the orientation of the southeast–northwest jet in the prototype microquasar GRS 1915 105. These results are based on three-epoch East Asia VLBI Network (EAVN) observations at 6.7 GHz, obtained during giant radio flares in 2025 detected by the RATAN-600 monitoring program. Our observations reveal the smallest position angle (PA) of 118° ± 7° ever measured for the jet in GRS 1915 105, which increases to 152° ± 2° within 37 days. Based on the literature results, we further suggest that the jet orientation has exhibited significant variations over a PA range of 118°–188° since 2023. This unusual jet orientation behavior in GRS 1915 105 during its current X-ray-obscured state may arise from a warped, precessing inner accretion disk, as implied by recent X-ray spectroscopy. Notably, one image reveals a peculiar morphology in GRS 1915 105, which likely indicates lateral spreading of the approaching southeast jet. Future observations are essential to

ALT Blazars and gamma-ray bursts (GRBs) are both cosmic beacons of extreme energy release powered by relativistic jets. However, they originate from tremendously different environments. Blazars are the sustained powerhouses driven by supermassive black holes at galactic centers, whereas GRBs are the transient death signals of massive stars or merging compact objects. Here we show that, despite the enormous differences, a universal physics defines the radiation spectra of blazars and GRBs. The blazar spectrum is well described by a "log-parabola" function. Employing a simple toy model with a single optically-thin region of a decreasing magnetic field, we produce the log-parabola spectrum very naturally for blazars. We find that the blazar spectrum is shaped by the "cooling physics" of relativistic electrons in the fast-cooling regime, which we identify as the universal physics since we previously showed that the fast-cooling physics of electrons with a decreasing magnetic field also explain

ALT We reanalyze previously reported gamma-ray periodicity candidates in jetted active galactic nuclei using more than 17 years of Fermi-LAT observations. The updated data provide a robust test of whether earlier results correspond to persistent periodic behavior, to transient quasi-periodic oscillations (QPOs), or to fluctuations produced by stochastic variability. We apply complementary timing methods, including the Generalized Lomb-Scargle periodogram, Phase Dispersion Minimization, and Singular Spectrum Analysis, and estimate the test statistics using artificial light curves generated from different variability models, including simple and bending power-law power spectral densities, as well as ARIMA and ARFIMA autoregressive models. We find that most previously proposed candidates in literature are not confirmed when the longer baseline is considered, indicating that many reported periods were likely driven by limited temporal coverage and red-noise variability or transient QPO-like fe

ALT We report recurrent X-ray state transitions in the nearby narrow-line Seyfert 1 galaxy Mrk 382 using multi-epoch observations from Swift, Chandra, XMM-Newton, and eROSITA, together with archival ultraviolet, optical, and infrared data. The 0.3–2 keV flux varies by nearly an order of magnitude over the past ∼15 yr, with multiple transitions between bright and faint states. The source brightened by a factor of ∼10 between the 2010 Chandra observation and the 2011 XMM-Newton high state, then declined by ∼6–7 to a low state in 2019, followed by renewed brightening in recent Swift monitoring. The X-ray spectrum shows strong state-dependent evolution, changing from a steep high-state continuum (Γ=2.32±0.04) to a much harder low-state spectrum (Γ=1.39±0.06). The low-state spectrum also exhibits a narrow Fe Kα line with an equivalent width of ∼330 eV. Reflection modeling indicates that the low-flux state is strongly reflection dominated, with the reflection fraction increasing from R_refl∼4 to

ALT We report the discovery and phase connected-timing solution of a second millisecond binary pulsar, PSR J1717 4308B (M92B), in the globular cluster M92 (NGC 6341) using the Five-hundred-meter Aperture Spherical radio Telescope. This new pulsar, with a spin period of 3.51 ms and a dispersion measure (DM) of 35.29 pc cm⁻³, was discovered through frequency-domain acceleration searches. The timing solution shows that M92B is in a binary system with an orbital period of 2.3 days, an eccentricity of ≃ 4.8 × 10⁻⁴, and a minimum companion mass of 0.2 M⊙. M92B lies within the cluster core radius in projection, and its negative spin period derivative (Ṗ) is consistent with acceleration in the cluster potential. The measured negative Ṗ of M92B, together with a DM consistent with that of M92A (< 0.2 pc cm⁻³), confirms that both pulsars are members of the cluster. A Bayesian Markov Chain Monte Carlo analysis based on these two pulsars yields broad constraints on the core structural parameters of M92

ALT Despite proximity of SN 2023ixf and a wealth of observational data, the released hydrodynamic models leave too broad range of the derived explosion energy and the ejected mass. We revisit the hydrodynamic modeling based on a broader set of observables than have been previously used. Among those of top priority is the early maximum ejecta velocity that is crucial in removing parameter degeneracy. The inferred parameters of SN 2023ixf are the explosion energy of 2.8x10⁵¹ erg, ejecta mass of 13.2 Msun, presupernova radius of 1540 Rsun, and Ni-56 mass of 0.07 Msun. The circumstellar matter is composed by the dense circumstellar shell with the mass of 0.01 Msun and radius of 5x10¹⁴ cm, as well as the external rarefied wind. Both circumstellar components are consistent with the early H-alpha broad wings caused by the Thomson scattering and the intrinsic column density provided by X-ray data. Based on the radiation hydrodynamics we, for the first time, simulate the SN 2023ixf phenomenon from

ALT X-ray flaring activity from active galactic nuclei (AGNs) may mimic the expected emission from tidal disruption events (TDEs), thus contaminating TDE searches. To compare X-ray emission properties between TDEs and AGNs, we cross-match publicly available XMM-Newton and Swift-XRT point source catalogs with the Million Quasars Catalog and optically selected TDEs. We find that AGNs tend to become softer with a similar hardness ratio (HR) value as TDEs during their flaring events. The soft HRs during flaring events in these AGNs are driven by the emergence of a blackbody-like component below ∼2 keV, likely associated with the soft X-ray excess, as well as the continuum emission becoming steeper with the increase of accretion rate. We find 2.5% in XMM-Newton (23 out of 920) and 4.4% in Swift-XRT (179 out of 4089) AGNs display flares with peak count rate >2σ from the median count rate and peak HR<-0.75. The rate of such flares in XMM-Newton and Swift-XRT is (1.1-2.5)×10⁻³{ gal}axy⁻¹ yr⁻¹ and

ALT We study the Bayesian reconstruction of peaked domain-wall gravitational-wave signals at LISA and construct reconstruction maps over the signal-parameter plane. These maps identify the regions in which the signal can be probed with minimal posterior uncertainty and parameter degeneracy. Our analysis employs a two-parameter domain-wall spectral template and includes isotropic, unmodulated astrophysical foregrounds from Galactic double white-dwarf binaries and extra-galactic compact binaries, together with LISA instrumental noise. The inference is performed for 64 injection points distributed on an equidistant grid using nested sampling, and the resulting posterior quantities are interpolated with the Clough–Tocher method to generate smooth maps over the full parameter plane. We find that LISA reconstructs domain-wall signals most effectively when the annihilation temperature lies approximately in the range 10³–10⁶ GeV. In this regime, the posterior becomes both tighter and less degenera

ALT We investigate the properties of low angular momentum, inviscid, advective accretion flows in a generic static and spherically symmetric spacetime that incorporates higher-order corrections up to the fourth order in 1/r. Employing this metric, we self-consistently solve the relativistic hydrodynamical equations and obtain the family of global transonic accretion solutions (O, A, W and I-types) by means of the spacetime parameters (δ, η, β) and the flow parameters (specific energy ℰ and angular momentum λ). Our analysis reveals that the accretion flow possesses either single or multiple critical points depending on these input parameters. We delineate the regions of the δ-λ and λ-ℰ parameter spaces that admits solutions with multiple critical points and demonstrate how these regions evolve with increasing spacetime parameter δ. Furthermore, while connecting the spacetime geometry with observable signatures, we compute the spectral energy distribution (SED) from thermal bremsstrahlung em

ALT Observations of peculiar GRBs have challenged the traditional T₉₀-based classification, demonstrating that duration does not map uniquely onto progenitor type. A striking class is long-duration Type I GRBs – merger-origin events whose prompt emission lasts far longer than the canonical 2 s boundary, typically comprising an initial short hard spike followed by softer extended emission. Identifying the physical origin of such bursts requires diagnostics beyond duration alone, among which the Amati relation, linking rest-frame spectral peak energy Ep,z and isotropic-equivalent energy Eᵢₛₒ, is widely used as a complementary classification tool. We analyze a sample of eight long-duration Type I GRBs and merger candidates by separating the initial spike from the extended emission and examining their episode-dependent locations on the Ep,z–Eᵢₛₒ plane. We find that the initial spike generally lies within, or close to, the empirical Type I region, consistent with a compact-merger-like prompt-em

ALT We perform a joint analysis of the high-energy neutrino emission observed from the Galactic Plane by IceCube and the diffuse ultra-high-energy gamma-ray emission measured by LHAASO. We compare this data to models that include diffuse emission from cosmic-ray interactions in the interstellar medium, unresolved TeV halos, and unresolved Galactic neutrino sources. We find that the gamma-ray emission can be explained by a combination of diffuse processes and unresolved TeV halos. The observed neutrino emission cannot be generated by cosmic-ray interactions in the interstellar medium alone, but requires contributions from one or more unresolved source populations. Across a wide range of assumptions about Galactic cosmic-ray transport, we find that Galactic neutrino sources contribute significantly to the neutrino flux observed from the Galactic Plane and are likely responsible for most of this emission.

ALT We study the impact of collisions involving red giants (RGs) in the dense stellar environments of galactic nuclei. We analytically estimate when collisions with main-sequence stars or stellar-mass black holes can strip a RG's envelope via ram pressure or accretion-driven shocks, or eject its helium core through gravitational recoil. At high velocities, v≳10³ km/s, collisions with main-sequence stars efficiently deplete the RG population. At lower velocities, collisions with stellar-mass BHs typically dominate over stellar encounters, but the overall RG destruction rate is low and does not significantly affect the RG population. Nonetheless, these collisions produce low-mass helium white dwarfs, which are the stripped cores of the disrupted RGs, at a rate of ∼ 500 Gyr⁻¹. Helium white dwarfs can produce an interesting class of white dwarf tidal disruption events around ∼ 10⁵⁻⁶ M⊙ massive black holes where Carbon-Oxygen white dwarfs cannot be tidally disrupted outside the horizon. Applied

ALT We present a numerical investigation into the precessing jets of the inner lobes of Centaurus A, focusing on their dynamical evolution and interaction with the surrounding medium. Using three-dimensional relativistic hydrodynamic simulations, we model the development of large-scale jet and lobe structures driven by precession. Our setup incorporates physically motivated parameters to reproduce observed morphological features. We compare the resulting structures from our simulations with observed radio images of Centaurus A, particularly focusing on the S-shaped morphology, the distribution of bright emission regions, and the observed asymmetry between the northern and southern lobes. Our findings indicate a precession period of 1.8 Myr, which reproduces observational characteristics. This study explores the role of jet precession in shaping the inner lobes of Centaurus A.

ALT Low-frequency gravitational waves (≤ssapprox 50 Hz) from core-collapse supernovae are becoming more important for current and future gravitational wave studies. This frequency region is dominated by the global morphology of the explosion and the anisotropic emission of neutrinos from the event. This paper serves as a brief review of both theory and detection (prospects) for gravitational waves in the low-frequency region. We discuss the generation of the linear gravitational wave memory sourced from neutrino emission and show results from an example 15 M_odot Solar metallicity progenitor. We also discuss the detection of the linear gravitational wave memory in current detectors, utilizing a combination of a linear predictive filter and matched templating. Finally we will discuss detection prospects in future detectors such as Cosmic Explorer, Einstein Telescope, the Laser Interferometer Space Antenna, and the Lunar Gravitational-wave Antenna.