Quasi-blackbody component and radiative efficiency of the prompt emission of gamma-ray bursts

Understand

We perform time-resolved spectroscopy on the prompt emission in gamma-ray bursts (GRBs) and identify a thermal, photospheric component peaking at a temperature of a few hundreds keV.

• This peak does not necessarily coincide with the broad band (keV-GeV) power peak.
• We show that this thermal component exhibits a characteristic temporal behavior.
• We study a sample of 56 long bursts, all strong enough to allow time-resolved spectroscopy.