A double component in the prompt emission of GRB 090618

TL;DR

This paper analyzes GRB 090618's prompt emission, revealing it cannot be explained by traditional single-component models and suggesting a more complex structure, using the fireshell scenario.

Contribution

It demonstrates that GRB 090618's emission requires a multi-component model, challenging the traditional single-component framework for gamma-ray bursts.

Findings

First episode of ~50s duration is non-canonical

Residual emission fits existing models

Single-component models are insufficient

Abstract

GRB 090618 offered an unprecedented opportunity to have coordinated data, by the best of the X and Gamma Ray observatories, of the nearest (z = 0.54) energetic source (10$^{54}$ erg). Using the Fermi-GBM observations of this GRB, we have analyzed this source to explore the possibility of having components yet to be observed in other sources. We show that it is not possible to interpret GRB 090618 within the framework of the traditional single component GRB model. We argue that the observation of the first episode of duration of around 50s could not be a part of a canonical GRB, while the residual emission could be modeled easily with the models existing in literature. In this work we have considered the case of the fireshell scenario.