2008ApJ...677..425L -
Astrophys. J., 677, 425-431 (2008/April-2)
Analytical solutions for expanding fireballs.
LI C. and SARI R.
Abstract (from CDS):
Many models of gamma-ray bursts (GRBs) as well as of soft gamma repeaters (SGRs) involve a fireball–an optically thick concentration of radiation energy with a high ratio of energy density to rest mass. We study the asymptotic behavior of an ultrarelativistic fireball consisting of electron-positron pairs and photons. We show that in the ultrarelativistic limit, after photons decouple from the pairs, the photon distribution function remains a blackbody spectrum in some appropriate Lorentz frame, allowing us to define an effective Lorentz factor and temperature for the photon gas. We also study the freezing out of electron-positron pairs and their asymptotic Lorentz factor γ∞. The dependence of these quantities on initial conditions can be described by simple scaling laws. We apply our results to SGR 1806-20 and find that the energy carried by electron-positron pairs is higher than calculated by former estimates, but is still an order of magnitude short of the minimum energy required to produce the observed afterglow. A viable solution of the energy budget is that the fireball is loaded by baryons or electromagnetic flux.
Abstract Copyright:
∼
Journal keyword(s):
Gamma Rays: Bursts - Hydrodynamics - Radiative Transfer
Simbad objects:
1
Full paper
View the references in ADS
To bookmark this query, right click on this link: simbad:2008ApJ...677..425L and select 'bookmark this link' or equivalent in the popup menu