Published in Space Science Reviews, Volume 134, Issue 1-4, pp. 51-70
astro-ph/0801.0977

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SOFT X-RAY AND EXTREME ULTRAVIOLET EXCESS EMISSION FROM CLUSTERS OF GALAXIES

F. Durret ¹, J. S. Kaastra ^{2, 3}, J. Nevalainen ⁴, T. Ohashi ⁵ and N. Werner ^{2, 6}

¹ Institut d'Astrophysique de Paris, CNRS, UMR 7095, Université Pierre et Marie Curie, 98bis Bd Arago, F-75014 Paris, France durret@iap.fr
² SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, the Netherlands
³ Astronomical Institute, Utrecht University, P.O. Box 80000, 3508 TA Utrecht, The Netherlands
⁴ Observatory, P.O. Box 14, 00014 University of Helsinki, Finland
⁵ Department of Physics, Tokyo Metropolitan University, 1-1 Minami-Osawa, Tokyo 192-0397, Japan
⁶ SRON Netherlands Institute for Space Research, Sorbonnelaan 2, NL - 3584 CA Utrecht, the Netherlands
Max Planck Institute für Astrophysik, Karl-Schwarzschild-Strasse 1, 85749, Garching, Germany

Abstract. An excess over the extrapolation to the extreme ultraviolet and soft X-ray ranges of the thermal emission from the hot intracluster medium has been detected in a number of clusters of galaxies. We briefly present each of the satellites (EUVE, ROSAT PSPC and BeppoSAX, and presently XMM-Newton, Chandra and Suzaku) and their corresponding instrumental issues, which are responsible for the fact that this soft excess remains controversial in a number of cases. We then review the evidence for this soft X-ray excess and discuss the possible mechanisms (thermal and non-thermal) which could be responsible for this emission.

Key words: Galaxies: clusters X-ray: spectra

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