Gamma-Ray Bursts

Abstract

Gamma-ray bursts (GRBs) are short and intense bursts of ∼100 keV−1MeV photons, usually followed by long-lasting decaying afterglow emission in a wide range of electromagnetic wavelengths from radio to Xray and, sometimes, even to GeV gamma-rays. These emissions are believed to originate from a relativistic jet, which is driven due to the collapse of special massive stars and the mergers of compact binaries (i.e., double neutron stars or a neutron star and a black hole). This chapter first briefly introduces the basic observational facts of the GRB phenomena, including the prompt emission, afterglow emission, and host galaxies. Secondly, a general theoretical understanding of the GRB phenomena is described based on a relativistic jet's overall dynamical evolution, including the acceleration, propagation, internal dissipation, and deceleration phases. Here a long-lasting central engine of the GRBs can substantially influence the dynamical evolution of the jet. In addition, a supernova/kilonova emission can appear in the optical afterglow of some nearby GRBs, which can provide an important probe to the

γ rays run on time, and propagate tailgating gravitational waves

“…The oldest γ-ray event detections known to us are all below z = 10, such as the recent GRB 210905A [23] above and near z = 6 or the older GRB 090423 [24] at z = 8.2; this is the reason why we have limited our discussion to redshifts up to ten, which include much of the reionization era. However, the James Webb Space Telescope may be detecting the afterglows of γ-ray bursts even above z = 10 [25] and it would be interesting to see if future detectors can detect the γ photons from such early-universe events. This will not be possible for very-and ultra-high energy γ rays since the universe is opaque for photons with energies above 100 GeV and redshifts above 3 (as hinted from figure 1, for example, or obvious from [16]).…”

The statistical characteristics of the prompt emission lightcurves of gamma‐ray bursts

“…Gamma-ray bursts (GRBs) are the most violent explosions in the universe (Yu et al 2022). The radiation generally consists of two stages, one is the prompt emission stage primarily in gamma-ray band, and the other one is the afterglow emission stage in the lower energy band from radio to X-ray.…”