  Clusters of galaxies are strong emitters of EUV and soft X-rays substantially
in excess of the contribution from the hot intra-cluster medium at X-ray
temperatures. After the initial discovery of EUV excess emission in the Virgo
cluster, the phenomenon was reported also for the Coma, A1795 and A2199
clusters. Recent reobservations confirmed the finding, and further searches on
a large sample of nearby galaxy clusters are clearly revealing the cosmological
impact of the discovery.
