Particle injection and reacceleration in clusters of galaxies and the EUV excess: the case of Coma

Abstract

We calculate the energy distribution of the relativistic particles injected in the ICM during a phase of reacceleration of the relativistic particles in the cluster volume. We apply our results to the case of the Coma cluster in which recent merging activity and the presence of the radio halo may suggest that reacceleration processes are efficient. We find that the electron population injected in the central part of the cluster by the head-tail radio galaxy NGC 4869 may account for a large fraction, if not all, of the detected EUV excess via inverse Compton scattering of the cosmic microwave background (CMB) photons. If radio haloes are powered by reacceleration mechanisms active in the cluster volume, moderate non-thermal EUV excesses (of order of $\sim 1-5\cdot 10^{42}$erg s^{-1}) should be a common feature of clusters containing powerful head-tail radio galaxies and/or AGNs.

22 pages, plus 9.ps figures, Latex, elsart.cls included, New Astronomy, accepted

References in corpus (3)

• Particle reacceleration in Coma cluster: radio properties and hard X-ray emission
• EUV Emission in Abell 1795, Abell 2199, and the Coma Cluster
• Extreme Ultraviolet Emission from Abell 4059

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• Spectral properties and origin of the radio halo in A3562
• Soft X-ray Excess in the Coma Cluster from a Cosmic Axion Background
• On the non-thermal high energy radiation of galaxy clusters
• The EUV Emission in the Coma Cluster of Galaxies and the Underlying Source of this Radiation
• Testing the cosmic ray content in galaxy clusters
• Analytical Models for the Energetics of Cosmic Accretion Shocks, their Cosmological Evolution, and the Effect of Environment
• A deep study of A399-401: An application for wide-field facet calibration