2010/03/12 by Asaf Pe’er, Asaf Pe'er, Pe'er, Asaf +3
Physics and Astronomy · #Astro and Planetary Science #Astronomy and Astrophysical Research #FOS: Physical sciences #Gamma-ray bursts and supernovae #High Energy Astrophysical Phenomena (astro-ph.HE) #astro-ph.HE
paper · pdf · doi:10.48550/arxiv.1003.2582
6 pages, Proceedings for "The Shocking Universe - Gamma-Ray Bursts and High Energy Shock phenomena", Venice, 14-18 September 2009.
arxiv created 2010/03/12 · openalex publication_date 2010/03/12 · arxiv updated 2010/03/15 · openalex created_date 2022/08/29 · openalex updated_date 2026/07/28
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 FBB ~ t-2, and the observed temperature as T ~ t-α, with α~ 1/2 - 2/3. These theoretical predictions are in very good agreement with the observations. Finally, we discuss three implications of this interpretation: (a) The relation between thermal emission and high energy, non-thermal spectra observed by Fermi. (b) We show how thermal emission can be used to directly measure the Lorentz factor of the flow and the initial radius of the jet. (c) We show how the lack of detection of the thermal component can be used to constrain the composition of GRB jets.