Chandra measurements of the distribution of mass in the luminous lensing cluster Abell 2390

Abstract

We present spatially resolved X-ray spectroscopy of the luminous lensing cluster Abell 2390, using observations made with the Chandra observatory. The temperature of the X-ray gas rises with increasing radius within the central ∼ 200 kpc of the cluster, and then remains approximately isothermal, with kT = 11.5+1.5-1.6keV, out to the limits of the observations at r ∼ 1.0 Mpc. The total mass profile determined from the Chandra data has a form in good agreement with the predictions from numerical simulations. Using the parametrization of Navarro, Frenk and White, we measure a scale radius rs ∼ 0.8 Mpc and a concentration parameter c ∼ 3. The best-fitting X-ray mass model is in good agreement with independent gravitational lensing results and optical measurements of the galaxy velocity dispersion in the cluster. The X-ray gas to total mass ratio rises with increasing radius with fgas ∼ 21 per cent at r = 0.9 Mpc. The azimuthally averaged 0.3-7.0 keV surface brightness profile exhibits a small core radius and a clear 'break' at r ∼ 500 kpc, where the slope changes from SX ∝∼ r -1.5 to SX ∝∼ r-3.6. The data for the central region of the cluster indicate the presence of a cooling flow with a mass deposition rate of 200-300 M⊙ yr-1 and an effective age of 2-3 Gyr.