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arXiv · 1103.4823

Gamma-ray bursts afterglows in magnetized stellar winds

Martin Lemoine·Guy Pelletier
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Abstract

Recent analytical and numerical work argue that successful relativistic Fermi acceleration requires a weak magnetization of the unshocked plasma, all the more so at high Lorentz factors. The present paper tests this conclusion by computing the afterglow of a gamma-ray burst outflow propagating in a magnetized stellar wind using "ab initio" principles regarding the microphysics of relativistic Fermi acceleration. It is shown that in magnetized environments, one expects a drop-out in the X-ray band on sub-day scales as the synchrotron emission of the shock heated electrons exits the frequency band. At later times, Fermi acceleration becomes operative when the blast Lorentz factor drops below a certain critical value, leading to the recovery of the standard afterglow light curve. Interestingly, the observed drop-out bears resemblance with the fast decay found in gamma-ray bursts early X-ray afterglows.

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Martin Lemoine, Guy Pelletier. 2011-08-30. Gamma-ray bursts afterglows in magnetized stellar winds. https://doi.org/10.1111/j.1745-3933.2011.01144.x

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