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

We present an estimate of the bolometric X-ray luminosity-velocity dispersion (Lx–σv) 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(σv) gives Lx= 1032.72±0.08σ4.1 ± 0.3v erg s−1h−250. 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 and σv–T. From this sample we obtain Lx∝T3.1±0.2 and σv∝T1.00±0.16, which are fully consistent with the above result for Lx–σv. The slopes of Lx–T and σv–T are incompatible with the values predicted by self-similarity (Lx∝T2∝σ4v), 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(σv) supports the self-similar model.