Gamma-ray bursts: A brief survey of the diversity

TL;DR

This paper surveys the diverse classifications of gamma-ray bursts, highlighting their different origins, potential subgroups, and recent statistical findings that suggest more complexity than the traditional short and long categories.

Contribution

It provides a concise overview of the current understanding and recent statistical evidence for multiple subgroups within gamma-ray bursts, emphasizing their astrophysical origins and diversity.

Findings

Existence of multiple GRB subgroups beyond short and long.

Potential intermediate and ultra-long GRB categories.

Long/soft GRBs may be divided by luminosity.

Abstract

The separation of the gamma-ray bursts (GRBs) into short/hard and long/soft subclasses, respectively, is well supported both theoretically and observationally. The long ones are coupled to supernovae type Ib/Ic - the short ones are connected to the merging of two neutron stars, where one or even both neutron stars can be substituted by black holes. These short GRBs - as merging binaries - can also serve as the sources of gravitation waves, and are observable as the recently detected macronovae. Since 1998 there are several statistical studies suggesting the existence of more than two subgroups. There can be a subgroup having an intermediate durations; there can be a subgroup with ultra-long durations; the long/soft subgroup itself can be divided into two subclasses with respect to the luminosity of GRBs. The authors with other collaborators provided several statistical studies in this topic. This field of the GRB-diversity is briefly surveyed in this contribution.