# The maximum isotropic energy of gamma-ray bursts

## TL;DR

This study investigates the upper limit of energy released by gamma-ray bursts, revealing a cutoff in their energy distribution around 10^{54} erg, which suggests an intrinsic energy constraint in these cosmic events.

## Contribution

The paper introduces a method to reconstruct the bright end of the GRB energy distribution and identifies a fundamental energy cutoff, advancing understanding of GRB energetics.

## Key findings

- GRB energy distribution has a cutoff at ~10^{54} erg.
- The distribution cannot be described by a simple power law.
- An intrinsic energy limit per unit solid angle is suggested.

## Abstract

The most energetic gamma-ray bursts (GRBs) are remarkable sources releasing huge amounts of energy on short timescales. Their prompt emission, which usually lasts few seconds, is so bright that it is visible across the whole observable universe. Studying these extreme events may provide clues on the nature of GRB progenitors and on the physical processes at work in relativistic jets. In this paper, we study the bright end of the isotropic energy distribution of long GRBs. We use two samples of long GRBs with redshift detected by Fermi/GBM or Konus-Wind, two instruments which measure the spectral shape and the energetics of the prompt emission accurately. We focus on GRBs within a range of redshifts z = 1 -- 5, a volume that contains a large number of energetic GRBs, and we propose a simple method to reconstruct the bright end of the GRB energy distribution from the observed one. We find that the GRB energy distribution cannot be described by a simple power law but requires a strong cutoff above $1-3 \times 10^{54}$ erg. We attribute this feature to an intrinsic limit on the energy per unit of solid angle radiated by gamma-ray bursts.