2012/07/25 by The Fermi LAT Collaboration, M. Axelsson, L. Baldini +100 · 9 citations
Physics and Astronomy · #Astro and Planetary Science #Astronomy #Astrophysics #Astrophysics and Cosmic Phenomena #Black-body radiation #Energy (signal processing) #Fermi Gamma-ray Space Telescope #Flux (metallurgy) #Gamma-ray burst #Gamma-ray bursts and supernovae #Optics #Photosphere #Physics #Radiation #Spectral line #Synchrotron #Telescope #astro-ph.CO #astro-ph.HE
paper · pdf · doi:10.1088/2041-8205/757/2/l31
published as ApJ 757 (2012) L31 · 5 pages, 4 figures, submitted 120721 to ApJL
arxiv created 2012/07/25 · openalex publication_date 2012/09/17 · arxiv updated 2012/09/19 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
GRB110721A was observed by the Fermi Gamma-ray Space Telescope using its two instruments, the Large Area Telescope (LAT) and the Gamma-ray Burst Monitor (GBM). The burst consisted of one major emission episode which lasted for ∼24.5 s (in the GBM) and had a peak flux of (5.7 ± 0.2) × 10 −5 erg s −1 cm −2 . The time-resolved emission spectrum is best modeled with a combination of a Band function and a blackbody spectrum. The peak energy of the Band component was initially 15 ± 2 MeV, which is the highest value ever detected in a GRB. This measurement was made possible by combining GBM/BGO data with LAT Low Energy events to achieve continuous 10–100 MeV coverage. The peak energy later decreased as a power law in time with an index of −1.89 ± 0.10. The temperature of the blackbody component also decreased, starting from ∼80 keV, and the decay showed a significant break after ∼2 s. The spectrum provides strong constraints on the standard synchrotron model, indicating that alternative mechanisms may give rise to the emission at these energies.