ChandraObservations of A2029: The Dark Matter Profile Down to below 0.01rvirin an Unusually Relaxed Cluster

Abstract

We have used a high resolution Chandra observation to examine the core mass distribution of the unusually regular cD cluster Abell 2029. This system is especially well-suited for analysis of its mass distribution under the assumption of hydrostatic equilibrium: it exhibits an undisturbed X-ray morphology and a single-phase ICM. We estimate the total mass, and the contributions of the gas and dark matter components from 100 beyond 200 kpc. The consistency with an NFW halo model and the large M/L suggest the cluster is DM-dominated down to <~ 0.01 r_vir. We observe a gas mass fraction = 0.139+/-0.004 at the limit of our observations, finding an upper limit to Omega_m <= 0.29+/-0.03 (abridged)