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

Wednesday, November 22, 2000 at 11:00

Andrei Bykov
St. Petersburg

A model for nonthermal emission from clusters of galaxies

Abstract. We present detailed kinetic modeling of nonthermal electron injection, acceleration and propagation in a virialized cluster of galaxies and find that the cluster halos are efficient electron accelerators and sources of extended hard X-ray and gamma-ray emission. The energy spectrum of the electrons is shaped by the joint action of first and second order Fermi acceleration at MHD shock fronts in a turbulent plasma with substantial Coulomb losses. Inverse-Compton, bremsstrahlung and synchrotron radiation by these electrons produce spectra that are in quantitative agreement with the hard X-ray and radio emission observed from the Coma cluster. We discuss also the nonthermal emission from large scale accretion shocks in clusters.

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