2013/12/10 by Yun-Feng Liang, Bei Zhou, Hao-Ning He +3
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Cosmic Phenomena #Energy density #Gamma-ray burst #Gamma-ray bursts and supernovae #High energy #Lorentz factor #Lorentz transformation #Outflow #Shock (circulatory) #Synchrotron radiation #astro-ph.HE
paper · pdf · doi:10.1088/0004-637x/781/2/74
7 pages, 4 figures, 2 tables, ApJ, in press
arxiv created 2013/12/10 · openalex publication_date 2014/01/10 · arxiv updated 2015/06/18 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
GRB 130821A was detected by Fermi -GBM/LAT, Konus- WIND , SPI-ACS/ INTEGRAL , RHESSI and Mars Odyssey -HEND. Although the data of GRB 130821A are very limited, we show in this work that the high energy γ-ray emission (i.e., above 100 MeV) alone imposes tight constraint on the density profile of the circum-burst medium as well as the initial Lorentz factor of the outflow. The temporal behavior of the high energy γ-ray emission is consistent with the forward shock synchrotron radiation model, and the circum-burst medium likely has a constant-density profile. The Lorentz factor is about a few hundred, similar to other bright GRBs.