The Peak Energy Distribution of the νFν Spectra and the Implications for the Jet Structure Models of Gamma-Ray Bursts
Abstract
We study the peak energy (Ep) distribution of the νFν spectra of gamma-ray bursts (GRBs) and X-ray flashes (XRFs) with a sample of 57 bursts observed by High Energy Transient Explorer (HETE-2) French Gamma Telescope and discuss its implications for the jet structure models. Combining the observed Ep distribution of HETE-2 GRBs/XRFs with that of BATSE GRBs, we find that the observed Ep distribution of GRBs/XRFs is a bimodal one with peaks of <~30 keV and ~160-250 keV. According to the recently discovered equivalent-isotropic energy-Ep relationship, such a bimodal distribution implies a two-component structure of GRB/XRF jets. A simple simulation analysis shows that this structured jet model does roughly reproduce a bimodal distribution with peaks of ~15 and ~200 keV. We argue that future observations of the peak of ~15 keV in the Ep distribution would be evidence supporting this model. Swift, which covers an energy band of 0.2-150 keV, is expected to provide a key test for our results.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- June 2004
- DOI:
- 10.1086/422253
- arXiv:
- arXiv:astro-ph/0403677
- Bibcode:
- 2004ApJ...608L...9L
- Keywords:
-
- Gamma Rays: Bursts;
- Gamma Rays: Observations;
- ISM: Jets and Outflows;
- Methods: Statistical;
- Astrophysics
- E-Print:
- 4 pages plus 2 figures, emulateapj style, ApJ Letters, 608, in press