Observations, theory and implications of thermal emission from gamma-ray bursts

Understand

Recent analyses show evidence for a thermal emission component that accompanies the non-thermal emission during the prompt phase of GRBs.

• First, we show the evidence for the existence of this component; Second, we show that this component is naturally explained by considering emission from the photosphere, taking into account high latitude emission from optically thick relativistically expanding plasma.
• We show that the thermal flux is expected to decay at late times as F_BB ~ t^{-2}, and the observed temperature as T ~ t^{-\alpha}, with \alpha ~ 1/2 - 2/3.
• These theoretical predictions are in very good agreement with the observations.