Standard GRB, Dirty Fireballs, and the Excluded Middle

TL;DR

This paper demonstrates that faint gamma-ray bursts contribute minimally to the overall energy flux, constraining models of GRB and dirty fireballs and implying a clear distinction between them.

Contribution

It provides quantitative limits on the energy contribution of faint GRBs, impacting theoretical models of GRB and dirty fireball populations.

Findings

Faint GRBs contribute little to total allsky flux

Total allsky GRB flux is approximately 5.3 x 10^{-3} erg/cm^2 per year

Results suggest a sharp division between GRB and dirty fireball models

Abstract

It is shown that the contribution of faint gamma-ray bursts (GRB) to the total allsky GRB energy flux is small. The allsky flux of GRB appears to be $5.3 \times 10^{-3}$ erg/$\rm cm^2 y$, with little additional component hidden within weak or otherwise undetectable GRB. This significantly constrains physical models of GRB and dirty fireballs, suggesting a rather sharp dichotomy between them should the latter exist.