2006 Supplement 1: WORKSHOP ON MULTIFREQUENCY BEHAVIOUR OF HIGH ENERGY COSMIC SOURCES: Frascati, 2005 / Dogiel

The Energetic Problem of X-Ray Emission from the Coma Cluster

V. A. Dogiel

Abstract


The stochastic acceleration of subrelativistic electrons from a background plasma is studied to find an explanation of the hard X-ray emission detected from the Coma cluster. We show that the temporal evolution of the electron distribution functions has, at its final stationary stage, a rather specific form determined by the interactions with charged background particles and electromagnetic fluctuations. These distribution functions cannot be described by simple exponential or power-law expressions. A broad transfer region is formed by Coulomb collisions at energies between the Maxwellian and power-law parts of the distribution functions. In this region the radiative lifetime of a single quasi-thermal electron differs greatly from the lifetime of the distribution function as a whole. This solves the problem of rapid cluster overheating by nonthermal electrons (Petrosian, 2001): while Petrosian's estimates are correct for nonthermal particles they are inapplicable in the quasi-thermal range.


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DOI: https://doi.org/10.1088/1009-9271/6/S1/09

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