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

Abstract

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±0.08σv4.1±0.3 erg s1- h50-2 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 ∝ σ v4), 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.