2016/01/06 by N. Fraija, Nissim Fraija, W. Lee +3 · 1 citation
Physics and Astronomy · #Adiabatic process #Afterglow #Astronomy and Astrophysical Research #Astrophysics and Cosmic Phenomena #Ejecta #Flux (metallurgy) #Gamma-ray burst #Gamma-ray bursts and supernovae #Photon #Synchrotron #Telescope #astro-ph.HE
paper · pdf · doi:10.3847/0004-637x/818/2/190
Accepted in ApJ (10 Pages, 4 figures)
arxiv created 2016/01/06 · openalex publication_date 2016/02/18 · arxiv updated 2016/03/09 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/06
ABSTRACT One of the most powerful gamma-ray bursts, GRB 130427A was swiftly detected from GeV γ -rays to optical wavelengths. In the GeV band, the Large Area Telescope (LAT) on board the Fermi Gamma-Ray Space Telescope observed the highest-energy photon ever recorded of 95 GeV and a bright peak in the early phase followed by emission temporally extended for more than 20 hr. In the optical band, a bright flash with a magnitude of 7.03 ± 0.03 in the time interval from 9.31 to 19.31 s after the trigger was reported by RAPTOR in r band. We study the origin of the GeV γ -ray emission, using the multiwavelength observation detected in X-ray and optical bands. The origin of the temporally extended LAT, X-ray, and optical flux is naturally interpreted as synchrotron radiation, and the 95 GeV photon and the integral flux upper limits placed by the high-altitude water Cerenkov observatory are consistent with synchrotron self-Compton from an adiabatic forward shock propagating into the stellar wind of its progenitor. The extreme LAT peak and the bright optical flash are explained through synchrotron self-Compton and synchrotron emission from the reverse shock, respectively, when the ejecta evolves in the thick-shell regime and carries a significant magnetic field.