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 is shown to rise with increasing radius within the central ~200 kpc of the cluster, and then remains approximately isothermal, with kT =11.5^{+1.5}_{-1.6} keV, 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 parameterization of Navarro, Frenk & White (1997), we measure a scale radius r_s~0.7 Mpc and a concentration parameter c~5. The best-fit X-ray mass model is in excellent agreement with independent measurements from strong and weak lensing studies and optical measurements of the galaxy velocity dispersion in the cluster. The X-ray gas-to-total-mass ratio rises with increasing radius within the central ~0.7 Mpc with f_gas \approxpropto r^{0.3}. At r = 0.9 Mpc, we measure f_gas = 15.7^{+5.6}_{-4.1} per cent (90 per cent confidence limits). 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 S_X \approxpropto r^{-1.4} to S_X \approxpropto r^{-3.7}. The data for the central ~70 kpc radius indicate the presence of a strong cooling flow with a mass deposition rate of 200-250 \Msunpyr and an age of ~3 Gyr.Keywords
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