A search for thermal X-ray signatures in Gamma-Ray Bursts II: The Swift sample

TL;DR

This study systematically searches for thermal X-ray signatures in Swift GRBs, finding six candidates with potential black body emission, which could be linked to supernova shock break-out, but detection is limited to specific conditions.

Contribution

It provides the first systematic search for black body components in Swift GRBs and characterizes their properties, highlighting detection limitations.

Findings

Six GRBs with possible black body components identified.

Detection likelihood depends on redshift and absorption environment.

Black body emission parameters estimated for candidate GRBs.

Abstract

In several gamma-ray bursts (GRBs) excess emission, in addition to the standard synchrotron afterglow spectrum, has been discovered in the early time X-ray observations. It has been proposed that this excess comes from black body emission, which may be related to the shock break-out of a supernova in the GRBs progenitor star. This hypothesis is supported by the discovery of excess emission in several GRBs with an associated supernova. Using mock spectra we show that it is only likely to detect such a component, similar to the one proposed in GRB 101219B, at low redshift and in low absorption environments. We also perform a systematic search for black body components in all the GRBs observed with the Swift satellite and find six bursts (GRB 061021, 061110A, 081109, 090814A, 100621A and 110715A) with possible black body components. Under the assumption that their excess emission is due to a black body component we present radii, temperatures and luminosities of the emitting components. We also show that detection of black body components only is possible in a fraction of the Swift bursts.