GeV emission from Gamma-Ray Burst afterglows

Abstract

We calculate the GeV afterglow emission expected from a few mechanisms related to GRBs and their afterglows. Given the brightness of the early X-ray afterglow emission measured by Swift/XRT, GLAST/LAT should detect the self-Compton emission from the forward-shock driven by the GRB ejecta into the circumburst medium. Novel features discovered by Swift in X-ray afterglows (plateaus and chromatic light-curve breaks) indicate the existence of a pair-enriched, relativistic outflow located behind the forward shock. Bulk and inverse-Compton upscattering of the prompt GRB emission by such outflows provide another source of GeV afterglow emission detectable by LAT. The large-angle burst emission and synchrotron forward-shock emission are, most likely, too dim at high photon energy to be observed by LAT. The spectral slope of the high-energy afterglow emission and its decay rate (if it can be measured) allow the identification of the mechanism producing the GeV transient emission following GRBs.

8 pages, accepted by MNRAS

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Cited by in corpus (9)

• High energy gamma-ray emission from Gamma-Ray Bursts -- before GLAST
• On the Implications of Late Internal Dissipation for Shallow-Decay Afterglow Emission and Associated High-Energy Gamma-Ray Signals
• GeV Emission from Prompt and Afterglow Phases of Gamma-Ray Bursts
• MAGIC observation of the GRB080430 afterglow
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• Less noticeable shallow decay phase in early X-ray afterglows of GeV/TeV-detected gamma-ray bursts
• GRB observations by Fermi LAT revisited: new candidates found
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