X‐Ray Measurements of the Gravitational Potential Profile in the Central Region of the Abell 1060 Cluster of Galaxies

Abstract

X-ray spectral and imaging data from ASCA and ROSAT were used to measure the total mass profile in the central region of Abell 1060, a nearby and relatively poor cluster of galaxies. The ASCA X-ray spectra, after being corrected for the spatial response of the X-ray telescope, show an isothermal distribution of the intracluster medium (ICM) within at least ~12' (or 160 h kpc; H0 = 70 h70 km s-1 Mpc-1) in radius of the cluster center. The azimuthally averaged surface brightness profile from the ROSAT Position Sensitive Proportional Counter (PSPC) exhibits a central excess above an isothermal β model. The ring-sorted ASCA Gas Imaging Spectrometer spectra and the radial surface brightness distribution from the ROSAT PSPC were simultaneously utilized to constrain the gravitational potential profile. Some analytic models of the total mass density profile were examined. The ICM density profile was also specified by analytic forms. The ICM temperature distribution was constrained to satisfy the hydrostatic equilibrium and to be consistent with the data. Then, the total mass distribution was found to be described better by the universal dark halo profile recently proposed by Navarro, Frenk, & White than by a King-type model with a flat density core. A profile with a central cusp together with a logarithmic radial slope of ~1.5 was also consistent with the data. Discussions are presented concerning the estimated dark matter distribution around the cluster center.