Self - similarity of clusters of galaxies and the L X − T relation

In this paper based on ROSAT/PSPC data we investigate the emission measure profiles of a sample of hot clusters of galaxies (kT > 3.5 keV) in order to explain the differences between observed and theoretically predicted LX–T relation. Looking at the form of the emission measure profiles as well as their normalizations we find clear indication that indeed the profiles have similar shapes once scaled to the virial radius, however, the normalization of the profiles shows a strong temperature dependence. We introduce a Mgas–T relation with the dependence Mgas ∝ T 1.94. This relationship explains the observed LX–T relation and reduces the scatter in the scaled profiles by a factor of 2 when compared to the classical scaling. We interpret this finding as strong indication that the Mgas–T relation in clusters deviates from classical scaling.