高能天体物理现象
Relativistic jets generated in gamma-ray bursts (GRBs) produce luminous transient events, yet the fundamentals of jet composition and radiation mechanisms remain unclear. One means of identifying a magnetically-dominated outflow would be…
Both the Rubin Observatory and the first telescopes of the CTAO will be collecting data by 2026, marking a new era in optical and gamma-ray astronomy. Compared to predecessors, their enhanced sensitivity will extend extragalactic…
X-ray pulsars (XRPs) consist of a magnetized neutron star (NS) and an optical donor star. The NS accretes matter from the donor star producing pulsed X-ray emission. In most cases the donor stars are Be stars, and accretion is episodic,…
The emissivity profile assumed in X-ray reflection spectroscopy significantly impacts black hole spin measurements. Using simulated NuSTAR spectra generated for lamppost and disk-like coronae with the relxill model suite, we evaluate…
We summarize the motivation for (as well as the presentations from) the April, 2024 workshop held in India and focused on radiowave techniques for cosmic ray and neutrino detection.
Large Array of imaging atmospheric Cherenkov Telescope (LACT) is an array of 32 Cherenkov telescopes with 6-meter diameter mirrors to be constructed at the LHAASO site, aiming to enhance our understanding of ultra-high energy gamma ray…
Type II supernovae (SNe II) are the most frequently observed outcome of core-collapse explosions and provide a valuable window into the physical mechanisms governing the deaths of massive stars. However, estimates of explosion properties…
SN 1993J is the best-studied radio supernova, with observations using very-long-baseline interferometry (VLBI) spanning from within weeks of explosion through nearly three decades of ejecta evolution. Imaging and modeling techniques have…
Galactic PeVatrons are astrophysical sources accelerating particles up to a few PeV (~10$^{15}$ eV). The primary method to identify both electron and proton PeVatrons is the observation of $\gamma$-ray radiation at ultra-high energies (UHE;…
Radio signals propagating through inhomogeneous plasma media deviate from their original paths, producing frequency-dependent magnification effects. In this paper, after reviewing the classical plasma-lensing theory, we have found a…
The $\gamma$-ray emission from active galactic nuclei (AGN), including both beamed blazars and misaligned-AGN, dominates the extragalactic $\gamma$-ray point-source population count and flux. While multi-wavelength studies have detected an…
Determining the spatial distribution of Galactic cosmic rays (CRs) is fundamental to understand how these particles propagate in interstellar space and to infer their source spectra. The most sensitive method of studying this problem is…
Binary neutron stars (BNSs) are among the most interesting sources for multimessenger studies. A number of recently discovered BNSs in the Milky Way by radio telescopes have added new information to the parameter distribution of the…
The widely anticipated outburst of recurrent nova T Coronae Borealis (T CrB), which is near the end of its 80-year cycle, provides an excellent opportunity to search for neutrinos from novae. Novae are an energetic class of transients,…
The diffuse Galactic neutrino flux is produced by cosmic rays interacting with the interstellar medium. The measurement of this flux can help to understand the distribution of cosmic rays in the Galaxy. The first observation of this…
While Supernova Remnants (SNRs) are widely considered the primary accelerators of cosmic rays (CRs) up to hundreds of TeV, they struggle to account for the CR flux at PeV energies, suggesting the existence of additional PeVatrons.…
The term PeVatron designates astrophysical objects capable of accelerating particles to PeV energies. Their nature and particle acceleration mechanisms are uncertain, but ultra-high-energy gamma rays are produced when particles accelerated…
We investigate the time evolution of sub-Keplerian transonic accretion flow onto a non-rotating black hole using axisymmetric viscous hydrodynamic simulations. We simulate the accretion flow using boundary values from semi-analytical…
The accretion-induced collapse (AIC) of a rotating white dwarf (WD) offers a potential site of millisecond pulsars/magnetars, gamma-ray bursts, and r-process nucleosynthesis. We present three-dimensional general-relativistic…
We performed a detailed time-resolved spectral study of GRS 1915+105 during its low-flux rebrightening phase using the broadband capabilities of AstroSat and NuSTAR in May-June 2019. The AstroSat light curves revealed erratic X-ray flares…