Data Centre for Astrophysics
Astronomy Department of the University of Geneva
ISDC Seminar

Wednesday, 19 October 2011 at 14:00

Rolf Buehler
Kavli/SLAC, Stanford University, USA

Gamma-ray flares from the Crab-nebula: A new astrophysical puzzle

Abstract. The Large Area Telescope on board the Fermi Satellite observed the brightest gamma-ray flare detected to date on April 2011. The gamma-ray brightness of the nebula doubled within ~10 hours reaching peak fluxes which are a factor 30 above the average nebula flux value. Surprisingly, simultaneous observations with the Chandra Satellite and the Keck observatory revealed no counterpart to the gamma-ray emission at lower wavelength. The observations give us a new view on the particle acceleration happening within the nebula and imply that the emission region is relativistically beamed towards us.

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