The X-ray luminosity-velocity dispersion relation in the REFLEX cluster survey

We present an estimate of the bolometric X-ray luminosity - velocity dispersion (Lxv) relation measured from a new, large and homogeneous sample of 171 low redshift, X-ray selected galaxy clusters. The linear fitting of log(Lx) log(�v) gives Lx = 10 32.72±0.08 � 4.1±0.3 v erg s 1 h 2 50 . Furthermore, a study of 54 clusters, for which the X-ray temperature of the intracluster medium T is available, allows us to explore two other scaling relations, Lx T andv T. From this sample we obtain Lx / T 3.1±0.2 andv / T 1.00±0.16 , which are fully consistent with the above result for the Lx-�v. The slopes of Lx T andv T are incompatible with the values predicted by self-similarity (Lx / T 2 / � 4), thus suggesting the presence of non-gravitational energy sources heating up the intracluster medium, in addition to the gravitational collapse, in the early stages of cluster formation. On the other hand, the result on log(Lx) log(�v) supports the self-similar model.