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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