高能天体物理现象
The Compton Spectrometer and Imager is a NASA satellite mission under development that will survey the entire sky in the 0.2-5 MeV range using a wide-field germanium detector array, surrounded on the sides and bottom by active shields (the…
The X-ray spectra of neutron stars with moderate magnetic fields ($B\sim 10^{12}$ G) in high-mass X-ray binaries (HMXBs) at low X-ray luminosities ($L_\mathrm{X}\lesssim 10^{35}$ erg/s) are characterized by a double humped shape. This shape…
In the 4FGL-DR4 point-source catalog of the Large Area Telescope (LAT) onboard NASA's Fermi Gamma-ray Observatory (Fermi-LAT), around a third of the sources are still unidentified (unIDs). In this work, we perform a detailed study of one of…
We study global transonic solution for a relativistic, magnetized, viscous advective accretion flow around a rotating black hole, incorporating the effects of mass and angular momentum loss through winds. Our model considers dominant…
The 2023/24 NICER monitoring campaign of the 7 Crab bright black hole X-ray binary Swift J1727.8-1613 covered the outburst in almost all accretion states. High-quality data are available in the high-Eddington-fraction hard-intermediate…
The James Webb Space Telescope (JWST) revealed a large population of active galactic nuclei (AGN) with redshifts greater than five. We show that if they emit ultrahigh-energy protons with energies up to $\lesssim 10^{19}$ eV, the cosmogenic…
The guiding center formalism is employed to analyze the motion of a charged relativistic particle in an inhomogeneous magnetic field, subject to magnetic mirroring and energy loss due to cooling. The governing equation for the evolution of…
We present detailed, multi-wavelength analysis of GRB 210704A: a Fermi Gamma-ray Burst Monitor discovered and Fermi Large Area Telescope (LAT) detected gamma-ray burst (GRB). The burst is dominated by a short ($\approx 2$ s) pulse followed…
Extragalactic Fast X-ray Transients (EFXTs) represent an emerging class of high-energy phenomena characterized by X-ray outbursts lasting from tens to hundreds of seconds. However, for more than half of the EFXTs, their physical origins…
We analyze data from a standard 3D general-relativistic magnetohydrodynamics (GRMHD) simulation, focusing on equatorial slices in order to examine the details and the evolution of the azimuthal structure of the accreting matter. During flux…
We study the effect of temperature on secular, compositional $g$-modes in the core of inviscid neutron stars. Using a chiral $SU(2)_f$ sigma model, we construct isentropic temperature profiles for hot and dense matter and find that the…
Gravitational wave (GW) and short Gamma Ray Burst (sGRB) observations provide us with complementary views of compact object mergers. The paucity of binary neutron star merger (BNS) detections in the latest LIGO/Virgo/KAGRA (LVK) observing…
This paper reports on the capabilities of the Cherenkov Telescope Array Observatory (CTAO) in detecting high-energy gamma-rays that show significant contributions of hadronic origin. We focus on four sources: RX J1713.7-3946, HESS…
Blazar gamma-ray variability is predominantly stochastic and well described by red-noise processes. However, a subset of sources shows quasi-periodic oscillations (QPOs) on year-long timescales, whose physical origin remains debated. In…
The MAGIC detection of near-TeV gamma rays from the 2021 RS Oph ($2.45$ kpc) outburst has established recurrent novae as TeV particle accelerators. However, the origin of this emission (hadronic vs leptonic) remains unclear due to the lack…
Galaxy observations suggest that mergers of supermassive black hole binaries (SMBHBs) are rare events, with rates of order one per decade across the observable Universe. We present a framework to search for merging SMBHBs in pulsar timing…
Active galactic nuclei (AGNs) are known to exhibit stochastic variability across a wide range of timescales and wavelengths. AGN flares are extreme outbursts that deviate from this typical behavior and may trace a range of energetic…
Star evolution models predict the lightest compact objects in the universe to have masses greater than that of the Sun. Nonetheless, alternative scenarios could lead to the formation of sub-solar mass (SSM) compact objects, such as…
We present new James Webb Space Telescope ($JWST$) NIRSpec and MIRI integral-field spectroscopy of the remarkable system SN~2010da / NGC~300 ULX-1, the only known ultraluminous X-ray source powered by a neutron star with a supergiant donor.…
Fast neutrino-flavor conversion (FFC) can nontrivially alter neutrino radiation field in core-collapase supernovae (CCSN) and binary neutron-star merger (BNSM) remnants. However, its interplay with global geometry remains poorly understood…