The Signature of the Central Engine in the Weakest Relativistic Explosions: GRB 100316D
Abstract
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 ~1049 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 \dot{M}\, {\sim }\, 10^{-5}\,M_{\odot }\,yr^{-1} (for an assumed wind density profile and wind velocity vw = 1000 km s-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.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- November 2013
- DOI:
- 10.1088/0004-637X/778/1/18
- arXiv:
- arXiv:1308.1687
- Bibcode:
- 2013ApJ...778...18M
- Keywords:
-
- gamma-ray burst: general;
- gamma-ray burst: individual: GRB 100316D;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 9 pages, Submitted to ApJ