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Article Dans Une Revue Astrophys.J. Année : 2015

Swift and Fermi observations of X-ray flares: the case of Late Internal Shock

E. Troja
  • Fonction : Auteur
L. Piro
  • Fonction : Auteur
N. Omodei
  • Fonction : Auteur
J.M. Burgess
  • Fonction : Auteur
S. Cutini
  • Fonction : Auteur
V. Connaughton
  • Fonction : Auteur
J.E. Mcenery
  • Fonction : Auteur

Résumé

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.

Dates et versions

hal-02051662 , version 1 (27-02-2019)

Identifiants

Citer

E. Troja, L. Piro, V. Vasileiou, N. Omodei, J.M. Burgess, et al.. Swift and Fermi observations of X-ray flares: the case of Late Internal Shock. Astrophys.J., 2015, 803 (1), pp.10. ⟨10.1088/0004-637X/803/1/10⟩. ⟨hal-02051662⟩
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