GRB 120422A: A LOW-LUMINOSITY GAMMA-RAY BURST DRIVEN BY A CENTRAL ENGINE

Journal Article · Mon Sep 10 04:00:00 EDT 2012 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/756/2/190· OSTI ID:22092334

Binbin, Zhang; Burrows, David N. ^[1]; Yizhong, Fan; Daming, Wei ^[2]; Shen, Rong-Feng ^[3]; Dong, Xu ^[4]; Fuwen, Zhang ^[5]; Bing, Zhang ^[6]; Gehrels, Neil ^[7]

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1. Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States)
2. Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China)
3. Department of Astronomy and Astrophysics, University of Toronto, M5S 3H4 (Canada)
4. Benoziyo Center for Astrophysics, Faculty of Physics, The Weizmann Institute of Science, Rehovot 76100 (Israel)
5. College of Science, Guilin University of Technology, Guilin, Guangxi 541004 (China)
6. Department of Physics and Astronomy, University of Nevada Las Vegas, Las Vegas, NV 89154 (United States)
7. NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

GRB 120422A is a low-luminosity gamma-ray burst (GRB) associated with a bright supernova, which distinguishes itself by its relatively short T{sub 90} ({approx}5 s) and an energetic and steep-decaying X-ray tail. We analyze the Swift Burst Alert Telescope and X-ray Telescope data and discuss the physical implications. We show that the steep decline early in the X-ray light curve can be interpreted as the curvature tail of a late emission episode around 58-86 s, with a curved instantaneous spectrum at the end of the emission episode. Together with the main activity in the first {approx}20 s and the weak emission from 40 s to 60 s, the prompt emission is variable, which points to a central engine origin in contrast to a shock-breakout origin, which is used to interpret some other nearby low-luminosity supernova GRBs. Both the curvature effect model and interpreting the early shallow decay as the coasting external forward shock emission in a wind medium provide a constraint on the bulk Lorentz factor {Gamma} to be around several. Comparing the properties of GRB 120422A and other supernova GRBs, we find that the main criterion to distinguish engine-driven GRBs from shock-breakout GRBs is the time-averaged {gamma}-ray luminosity. Engine-driven GRBs likely have a luminosity above {approx}10{sup 48} erg s{sup -1}.

• OSTI ID: 22092334
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 756; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ASTROPHYSICS
COSMIC GAMMA BURSTS
COSMIC PHOTONS
DIAGRAMS
GAMMA ASTRONOMY
LUMINOSITY
PHOTON EMISSION
STELLAR WINDS
SUPERNOVAE
TELESCOPE COUNTERS
VISIBLE RADIATION
X RADIATION