The rapid decline of the prompt emission in Gamma-Ray Bursts

TL;DR

This paper compares the high-latitude emission model and the cannonball model for the fast decline phase in gamma-ray bursts, finding the latter better explains the observed spectral softening and temporal behavior.

Contribution

It demonstrates that the cannonball model more accurately accounts for the spectral softening during the fast decline phase of GRBs compared to the standard fireball high-latitude emission model.

Findings

Cannonball model explains spectral softening in GRB decline phase.

High-latitude emission model does not account for spectral softening.

Temporal behavior aligns with cannonball model predictions.

Abstract

Many gamma ray bursts (GRBs) have been observed with the Burst-Alert and X-Ray telescopes of the Swift satellite. The successive `pulses' of these GRBs end with a fast decline and a fast spectral softening, until they are overtaken by another pulse, or the last pulse's decline is overtaken by a less rapidly-varying `afterglow'. The fast decline-phase has been attributed, in the currently-explored standard fireball model of GRBs, to `high-latitude' synchrotron emission from a collision of two conical shells. This high latitude emission does not explain the observed spectral softening. In contrast, the temporal behaviour and the spectral evolution during the fast-decline phase agree with the predictions of the cannonball model of GRBs.