Radio-bright vs. Radio-dark Gamma-ray Bursts -- More Evidence for Distinct Progenitors

TL;DR

This study compares radio-bright and radio-dark gamma-ray bursts, revealing significant differences in their gamma-ray properties and supporting the idea that they may originate from different progenitors.

Contribution

It provides an updated, larger sample analysis showing distinct gamma-ray and afterglow characteristics, strengthening the case for different progenitors.

Findings

Gamma-ray duration and energy distributions differ significantly between the two GRB types.

Radio-bright GRBs uniquely exhibit high-energy extended emission.

Anti-correlations between jet opening angle, redshift, and intrinsic duration are observed.

Abstract

We analyze two distinct samples of GRBs, with and without radio afterglow emission. We use a sample of 211 GRBs which is an update of the previous sample from arXiv:1902.01974, and find, in agreement with previous results (although with a sample that is almost twice as large) as the intrinsic gamma-ray duration (Tint) and isotropic equivalent energy (Eiso) distributions between these two populations appear to differ significantly. The redshift (z) distributions of the two samples are not statistically different. We analyze several correlations between variables (Eiso, Tint, jet opening angle, and z), accounting for selection effects and redshift evolution using the Efron-Petrosian method. We find a statistically significant anti-correlation between the jet opening angle and redshift, as well as between Tint and redshift, for both radio-bright and radio-dark GRBs. Finally, in agreement with previous work, we find that very high energy (0.1 - 100 GeV) extended emission is present in the radio-bright GRB sample only. Our work supports the possibility that the radio-bright and the radio-dark GRBs originate from different progenitors.