2011/07/25 by Motoko Serino, Atsumasa Yoshida, Nobuyuki Kawai +32 · 3 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Cosmic Phenomena #Black-body radiation #Energy (signal processing) #Fermi Gamma-ray Space Telescope #Gamma-ray burst #Gamma-ray bursts and supernovae #Lorentz factor #Spectral line #Spitzer Space Telescope #Telescope #astro-ph.HE
paper · pdf · doi:10.1093/pasj/63.sp3.s1035
published in Publications of the Astronomical Society of Japan 63(sp3), S1035-S1040 (Oxford University Press) · 7 pages, 6 figures
arxiv created 2011/07/25 · openalex publication_date 2011/11/25 · arxiv updated 2015/02/05 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Abstract The monitor of the all-sky X-ray image (MAXI) Gas Slit Camera (GSC) on the International Space Station (ISS) detected a gamma-ray burst (GRB) on 2009, September 26, GRB 090926B. This GRB had extremely hard spectra in the X-ray energy range. Joint spectral fitting with the Gamma-ray Burst Monitor on the Fermi Gamma-ray Space Telescope shows that this burst had a peculiarly narrow spectral energy distribution, which can be represented by a Comptonized blackbody model. This spectrum can be interpreted as photospheric emission from a low baryon-load GRB fireball. Calculating the parameter of the fireball, we found the size of the base of the flow to be r0= (4.3 ± 0.9) × 10 9 Y'-3/2 cm, the Lorentz factor of the plasma is Γ= (110 ± 10) Y' 1/4 , where Y' is a ratio between the total fireball energy and the energy in the blackbody component of the gamma-ray emission. This r0 is a factor of a few times larger, and the Lorentz factor of 110 is smaller by also factor of a few than other bursts that have blackbody components in the spectra.