An ASCA - ROSAT Study of the Distant , Lensing Cluster A 2390

We present the results of a combined study of ASCA and ROSAT observations of the distant cluster Abell 2390. For this cluster a gravitational arc as well as weak lensing shear have been previously discovered. We determine the surface brightness profile and the gas density distribution of the cluster from the ROSAT PSPC and HRI data. A combined spatially resolved spectral analysis of the ASCA and ROSAT data show that the temperature distribution of the intracluster medium of A2390 is consistent with an isothermal temperature distribution in the range 9 to 12 keV except for the central region. Within a radius of 160h −1 50 kpc the cooling time is found to be shorter than the Hubble time, implying the presence of a cooling flow. In this central region we find strong evidence for a multi-temperature structure. Detailed analysis of the combined ASCA and ROSAT data yields a self-consistent result for the spectral structure and the surface brightness profile of the cluster with a cooling flow of about 500 − 700 M ⊙ y −1 and an age of about 10 10 y. From the constraints on the temperature and density profile of the intracluster gas we determine the gravita-tional mass profile of the cluster and find a mass of about 2 · 10 15 M ⊙ within a radius of 3h −1 50 Mpc. A comparison of the projected mass profiles of the cluster shows an excellent agreement between the mass determined from X-ray data and the mass determined from the models for the gravitational arc and the weak lensing results. This agreement in this object, as compared to other cases where a larger lensing mass was implied, may probably be due to the fact that A2390 is more relaxed than most other cases for which gravitational lensing mass and X-ray mass have been compared so far.