Soft X-ray excess emission in clusters of galaxies observed with XMM-Newton

We present results on the spectroscopic analysis of XMM-Newton EPIC data of the central 0.5/h_50 Mpc regions of the clusters of galaxies Coma, A1795 and A3112. The temperature of the hot intracluster gas as determined by modeling the 2 - 7 keV PN and MOS data is consistent with that inferred from the FeXXV-FeXXVI line ratio. A significant warm emission component at a level above the systematic uncertainties is evident in the data and confirmed by ROSAT PSPC data for Coma and A1795. The non-thermal origin of the phenomenon cannot be ruled out at the current level of calibration accuracy, but the thermal model fits the data significantly better. The soft X-ray (0.2 - 2.0 keV) luminosity of the warm component is 10 - 30 % of that of the hot gas. The best-fit temperatures (0.6 - 1.3 keV), overdensities (200 - 1000) and metal abundances (0 - 0.15 of solar) of the warm component inside the central 0.5/h_50 Mpc are consistent with the results of recent cosmological simulations. Our results therefore offer observational support to the theories that predict a large fraction of the current epoch's baryons located in a warm-hot intergalactic medium