高能天体物理现象
The origins and acceleration mechanisms of ultra-high-energy cosmic rays (UHECRs) are unknown. Many models attribute their extreme energies to powerful astrophysical jets. Understanding whether jet geometry -- specifically the opening angle…
Faint $\gamma$-ray signatures emerge in Fermi-LAT data stacked scaled to the characteristic $\theta_{500}$ angles of MCXC galaxy clusters. After Paper I of this series thus discovered virial shocks, later supported in other bands, this…
Galaxy-cluster virial (structure-formation accretion) shock observations are shown to imply $\gtrsim1\%$ magnetization of a layer extending $\gtrsim10^{16}$ Debye lengths downstream, challenging the modelling of high Alfv\'en-Mach…
Cosmic ray (CR) knees (spectral steepenings) encode information on CR accelerator populations. We seek population features that imprint onto knee observables in a manner that is robust enough to be discernible even in the presence of…
The quark star (QS) is a hypothetical and yet undiscovered stellar object, and its existence would mark a paradigm shift in research on nuclear and quark matter. Although compactness is a well-known signature for distinguishing between two…
We report the search result for the Diffuse Supernova Neutrino Background (DSNB) in neutrino energies beyond 9.3~MeV in the gadolinium-loaded Super-Kamiokande (SK) detector with $22,500\times956.2$$~\rm m^3\cdot day$ exposure. %$22.5{\rm…
We analyzed 77 epochs of Atacama Large Millimeter/submillimeter Array (ALMA) archival data to investigate flux variability in Sagittarius A$^*$ (Sgr A$^*$), the supermassive black hole at the Galactic Center. Among these, we identified a…
Force-free electrodynamics describes the electromagnetic field of the magnetically dominated plasma found near pulsars and active black holes, but gives no information about the underlying particles that ultimately produce the observable…
We present an analysis of XMM-Newton X-ray observations of PJ1053+60, a hyperluminous infrared galaxy (HyLIRG) at z=3.549 that is strongly lensed by a foreground group at z=0.837. We also present GNIRS spectroscopy confirming the presence…
Pulsar timing arrays are sensitive to low-frequency gravitational waves (GWs), such as those produced by supermassive binary black holes at subparsec separations. The incoherent superposition of GWs emitted by a cosmological population of…
We present a timing analysis of the black hole X-ray binary (BHXRB) 4U 1630-47 using AstroSat observations from 10-19 March 2023, for the first time capturing a rare and rapid transition in variability properties. Within less than a day,…
We review the state of the evidence for the existence and observational appearance of supermassive black hole binaries. Such objects are expected from standard hierarchical galaxy evolution to form after two galaxies, each containing a…
The accretion flow in AGN is not well understood, motivating intensive monitoring campaigns of multiwavelength variability to probe its structure. One of the best of these is the 3 year optical/UV/X-ray approximately daily monitoring…
High-Mass X-ray Binaries (HMXBs) serve as useful laboratories for exploring the behaviour of accreted matter onto compact objects and for probing the complex wind environments of massive stars. These investigations are essential for…
The volumetric rates and luminosity functions (LFs) of core-collapse supernovae (ccSN) and their subtypes are important for understanding the cosmic history of star formation and the buildup of ccSN products. To estimate these rates, we use…
On July 2, 2025, the Gamma-ray Burst Monitor (GBM) onboard the Fermi Gamma-ray space telescope detected three short-duration MeV transients with overlapping sky locations. These events, named as GRB 250702D, B, and E (collectively referred…
Gamma-ray bursts (GRBs) offer a powerful window to probe the progenitor systems responsible for the formation of heavy elements through the rapid neutron capture (r-) process, thanks to their exceptional luminosity, which allows them to be…
Context. Young Massive Star Clusters, long considered as potentially important sources of galactic cosmic rays, have recently emerged as gamma-ray emitters up to very high energies. Aims. In order to quantify the contribution of this source…
The recent detection of the ultra-high-energy neutrino event KM3-230213A ($\sim$220 PeV) by KM3NeT telescope poses a challenge to conventional astrophysical models, particularly in light of the absence of similar $\gtrsim$100 PeV events in…
We investigate how AGN disk turbulence affects the orbital dynamics of a stellar-mass black hole (BH) initially located at a migration trap, focusing on the long-term behavior of eccentricity and inclination in the quasi-embedded regime. We…