X-ray flares from propagation instabilities in long gamma-ray burst jets

Type Journal Article
Names D. Lazzati, C. H. Blackwell, B. J. Morsony, M. C. Begelman
Publication Monthly Notices of the Royal Astronomical Society
Volume 411
Issue 1
Pages L16-L20
Date February 1, 2011
URL http://adsabs.harvard.edu/abs/2011MNRAS.411L..16L
Library Catalog NASA ADS
Abstract We present a numerical simulation of a gamma-ray burst jet from a long-lasting engine in the core of a 16 solar mass Wolf-Rayet star. The engine is kept active for 6000 s with a luminosity that decays in time as a power law with index -5/3. Even though there is no short time-scale variability in the injected engine luminosity, we find that the jet's kinetic luminosity outside the progenitor star is characterized by fluctuations with relatively short time-scale. We analyse the temporal characteristics of those fluctuations and we find that they are consistent with the properties of observed flares in X-ray afterglows. The peak-to-continuum flux ratio of the flares in the simulation is consistent with some, but not all, the observed flares. We propose that propagation instabilities, rather than variability in the engine luminosity, are responsible for the X-ray flares with moderate contrast. Strong flares such as the one detected in GRB 050502B, instead, cannot be reproduced by this model and require strong variability in the engine activity.
Tags gamma-ray burst: general, radiation mechanisms: non-thermal
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