2000A&A...353..124B

We report the analysis of a very deep ROSAT HRI observation on one of the most interesting, distant lensing clusters, Cl 0024+17. Using the X-ray surface brightness we analyse the cluster morphology and constrain the gas and gravitational mass of the cluster. We confirm the small core radius of the mass halo of 66_–25⁺38h₅₀^–1kpc for this cluster inferred previously from a detailed strong lensing analysis by Tyson et al. (1998ApJ...498L.107T) and Smail et al. (1997ApJ...479...70S). Using estimated gas temperatures we find a cluster mass of about 3-14x10¹⁴h₅₀^–1 M_☉ for a fiducial radius of 3h₅₀^–1Mpc. This mass is lower than the mass implied by the weak lensing result of Bonnet et al. (1994ApJ...427L..83B) and inconsistent with a virial analysis based on the high observed galaxy velocity dispersion. The lower gravitational mass found in the present study implies, however, a gas mass fraction of the cluster e.g. at 1 h₅₀^–1Mpc radius of 17(11-28) h₅₀^–1.5% well consistent with the general observations in rich clusters. This favours a lower mass value for the relaxed part of Cl 0024+17 which could still be embedded in a larger structure achieving a consistency with the weak lensing observations.