Swift and Fermi observations of X-ray flares: the case of Late Internal Shock
Nov 5, 2014
12 pages
Published in:
- Astrophys.J. 803 (2015) 1, 10
- Published: Apr 8, 2015
e-Print:
- 1411.1415 [astro-ph.HE]
View in:
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Abstract: (IOP)
Simultaneous Swift and Fermi observations of gamma-ray bursts (GRBs) offer a unique broadband view of their afterglow emission, spanning more than 10 decades in energy. We present the sample of X-ray flares observed by both Swift and Fermi during the first three years of Fermi operations. While bright in the X-ray band, X-ray flares are often undetected at lower (optical), and higher (MeV to GeV) energies. We show that this disfavors synchrotron self-Compton processes as the origin of the observed X-ray emission. We compare the broadband properties of X-ray flares with the standard late internal shock model, and find that in this scenario, X-ray flares can be produced by a late-time relativistic (Γ > 50) outflow at radii R ~ 10(13)-10(14) cm. This conclusion holds only if the variability timescale is significantly shorter than the observed flare duration, and implies that X-ray flares can directly probe the activity of the GRB central engine.Note:
- 13 pages, 4 figures, accepted for publication in ApJ
- gamma-ray burst: general
- radiation mechanisms: non-thermal
References(87)
Figures(16)