The photospheric radiation model for the prompt emission of Gamma-ray Bursts: Interpreting four observed correlations

TL;DR

This paper demonstrates that observed correlations in Gamma-ray Burst prompt emissions align well with predictions from the photospheric radiation model, suggesting a photospheric origin for these emissions.

Contribution

It provides the first comprehensive interpretation of four key observed correlations within the photospheric radiation framework for GRBs.

Findings

Observed correlations match model predictions

Thermal radiation from GRB 090902B follows key correlations

Alternative models lack reliable explanations for these correlations

Abstract

We show that the experiential $E_{\rm p}-L$, $\Gamma-L$, $E_{\rm p}-\Gamma$ and ${\rm \bar{\eta}_\gamma}-E_{\rm p}$ correlations (where $L$ is the time-averaged luminosity of the prompt emission, $E_{\rm p}$ is the spectral peak energy, $\Gamma$ is the bulk Lorentz factor and $\bar{\eta}_\gamma$ is the emission efficiency of Gamma-ray bursts) are well consistent with the relations between the resembling parameters predicted in the photospheric radiation model of the prompt emission of Gamma-ray bursts. The time-resolved thermal radiation of GRB 090902B does follow the $E_{\rm p}-L$ and $\Gamma-L$ correlations. A reliable interpretation of the four correlations in alternative models is still lacking. These facts may point towards a photospheric origin of prompt emission of some Gamma-ray Bursts.