The Rapid Decline of the Prompt Emission in Gamma-Ray Bursts
Abstract
Many gamma-ray bursts (GRBs) have been observed with the Burst Alert Telescope and X-Ray Telescope of the Swift satellite. The successive "pulses" of these GRBs end with a fast decline and a fast spectral softening, until they are overtaken by another pulse or the last pulse's decline is overtaken by a less rapidly varying "afterglow." The fast-decline phase has been attributed, in the currently explored standard fireball model of GRBs, to "high-latitude" synchrotron emission from a collision of two conical shells. This high-latitude emission does not explain the observed spectral softening. In contrast, the temporal behavior and the spectral evolution during the fast-decline phase agree with the predictions of the cannonball model for GRBs.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- July 2008
- DOI:
- 10.1086/587952
- arXiv:
- arXiv:0709.4307
- Bibcode:
- 2008ApJ...681.1408D
- Keywords:
-
- gamma rays: bursts;
- radiation mechanisms: non-thermal;
- X-rays: general;
- Astrophysics
- E-Print:
- Four added figures comparing the evolution of the inferred effective photon spectral index during the fast decline phase of the prompt emission in 14 selected Swift GRBS and the cannonball (CB) model prediction