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R. C. Berrington, C. D. Dermer (Naval Research Lab)
We have developed a numerical model for the temporal evolution of particle and photon spectra resulting from nonthermal processes at the shock fronts formed in merging clusters of galaxies. We approximate Fermi acceleration by injecting power-law distributions of particles during a merger event, subject to constraints on maximum particle energies. Synchrotron, bremsstrahlung, Compton, and Coulomb processes for the electrons, nuclear, photomeson, and Coulomb processes for the protons, knock-on electron production, and particle adiabatic heating during the merging process are considered. The broadband radio through gamma-ray emission radiated by nonthermal protons and primary and secondary electrons is calculated both during and after the merger event. Using ROSAT observations to establish typical parameters for the matter density profile of clusters of galaxies, we find that typical merger shocks are weak and accelerate particles with relatively soft spectra. We consider the prospects for detecting nonthermal radio and gamma-ray emission from clusters of galaxies and implications for the origin of ultra-high energy cosmic rays and the diffuse gamma-ray background. The temporal evolution of the nonthermal particle pressure is calculated for protons and primary and secondary electrons. We discuss implications on derived properties of the intracluster medium.
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The author(s) of this abstract have provided an email address for comments about the abstract: rberring@gamma.nrl.navy.mil
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Bulletin of the American Astronomical Society, 34, #4
© 2002. The American Astronomical Soceity.