Short Hard Gamma Ray Bursts And Their Afterglows

TL;DR

This paper analyzes short hard gamma-ray bursts (SHBs) using the cannonball model, explaining their prompt emission and afterglows through inverse Compton scattering and synchrotron radiation, and discusses their possible origins and environments.

Contribution

It applies the cannonball model to all Swift SHBs with well-sampled afterglows, providing a unified explanation for their emission mechanisms and origins.

Findings

Prompt gamma-ray emission explained by inverse Compton scattering.

Extended soft emission due to ICS of high-density light or synchrotron radiation.

No supernova detected in certain low-luminosity nearby SHBs, suggesting off-axis viewing.

Abstract

Long duration gamma ray bursts (GRBs) and X-ray flashes (XRFs) are produced by highly- relativistic jets ejected in core-collapse supernova explosions. The origin of short hard gamma-ray bursts (SHBs) has not been established. They may be produced by highly relativistic jets ejected in various processes: mergers of compact stellar objects; large-mass accretion episodes onto compact stars in close binaries or onto intermediate-mass black holes in dense stellar regions; phase transition of compact stars. Natural environments of such events are the dense cores of globular clusters, superstar clusters and young supernova remnants. We have used the cannonball model of GRBs to analyze all Swift SHBs with a well-sampled X-ray afterglow. We show that their prompt gamma-ray emission can be explained by inverse Compton scattering (ICS) of the progenitor's glory light, and their extended soft emission component by ICS of high density light or synchrotron radiation (SR) in a high density interstellar medium within the cluster. The mechanism generating the afterglow is synchrotron radiation outside the cluster. No associated supernova could be detected in the low luminosity nearby GRBs 060614 and 060505. We interpret them as SHBs seen relatively far off axis.