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Title: The signature of the central engine in the weakest relativistic explosions: GRB 100316D

We present late-time radio and X-ray observations of the nearby sub-energetic gamma-ray burst (GRB)100316D associated with supernova (SN) 2010bh. Our broad-band analysis constrains the explosion properties of GRB 100316D to be intermediate between highly relativistic, collimated GRBs and the spherical, ordinary hydrogen-stripped SNe. We find that ∼10{sup 49} erg is coupled to mildly relativistic (Γ = 1.5-2), quasi-spherical ejecta, expanding into a medium previously shaped by the progenitor mass-loss with a rate of M-dot ∼ 10{sup −5} M{sub ⊙} yr{sup −1} (for an assumed wind density profile and wind velocity v{sub w} = 1000 km s{sup –1}). The kinetic energy profile of the ejecta argues for the presence of a central engine and identifies GRB 100316D as one of the weakest central-engine-driven explosions detected to date. Emission from the central engine is responsible for an excess of soft X-ray radiation that dominates over the standard afterglow at late times (t > 10 days). We connect this phenomenology with the birth of the most rapidly rotating magnetars. Alternatively, accretion onto a newly formed black hole might explain the excess of radiation. However, significant departure from the standard fall-back scenario is required.
Authors:
; ; ; ; ;  [1] ; ;  [2] ;  [3] ;  [4] ;  [5] ;  [6]
  1. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
  2. CSIRO Astronomy and Space Science, Australia Telescope National Facility, P.O. Box 76, Epping, NSW 1710 (Australia)
  3. Astronomy Department, University of Virginia, Charlottesville, VA 22904 (United States)
  4. Department of Astronomy, University of Wisconsin-Madison, 2535 Sterling Hall, 475 N. Charter Street, Madison, WI 53706-1582 (United States)
  5. Racah Institute for Physics, Edmund J. Safra Campus, Hebrew University of Jerusalem, Jerusalem 91904 (Israel)
  6. Scuola Normale Superiore, 7, I-56126 Pisa (Italy)
Publication Date:
OSTI Identifier:
22342046
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 778; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; AFTERGLOW; BLACK HOLES; COSMIC GAMMA BURSTS; DENSITY; EMISSION; EXPLOSIONS; HYDROGEN; MASS TRANSFER; RELATIVISTIC RANGE; SOFT X RADIATION; SPHERICAL CONFIGURATION; STELLAR WINDS; VELOCITY