| Speaker: | Dr. Assaf Pe'er, Harvard-Smithsonian Center for Astrophysics |
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| Title: | THERMAL AND NON-THERMAL EMISSION IN THE PROMPT PHASE OF GRBs |
| Abstract: |
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The launch of Fermi opened a new era in the study of Gamma-Ray Bursts
(GRBs) prompt emission. The broad band data show complex behavior
that urge the need for a new interpretation. I will show that
photospheric (thermal) emission is naturally expected. Light
aberration in this relativistically expanding environment modifies
the Planck spectrum that is expected to be observed as a multicolor
black-body emission component. Moreover, these photons serve as seed
photons for Compton scattering by energetic electrons, following
kinetic energy dissipation above the photosphere. The high energy
spectrum therefore results from various radiative processes, and as
such is not easy to model. I will show how the analysis method
proposed results in a complete, self consistent picture of the
physical conditions at both emission sites of the thermal and
non-thermal radiation. Furthermore, it enables a new insight into the
physical conditions in the innermost regions of the outflow, hence
constrain progenitor models.
References Pe'er & Ryde, 2010, arXiv:1008:4590 Pe'er et. al., 2010, arXiv:1007:2228 Ryde et al., 2010, ApJ, 709, L172 Ryde & Pe'er, 2009, ApJ, 702, 1211 Pe'er, 2008, ApJ, 682, 436 |