Gemini and Chandra Observations of Abell 586, A Relaxed Strong‐lensing Cluster

Abstract

We analyze the mass content of the massive strong-lensing cluster Abell 586 (z = 0.17). We use optical data (imaging and spectroscopy) obtained with the Gemini Multi-Object Spectrograph (GMOS) mounted on the 8-m Gemini-North telescope, together with publicly available X-ray data taken with the textitChandra space telescope. Employing different techniques - velocity distribution of galaxies, weak gravitational lensing, and X-ray spatially resolved spectroscopy - we derive mass and velocity dispersion estimates from each of them. All estimates agree well with each other, within a 68% confidence level, indicating a velocity dispersion of 1000 - 1250 kms. The projected mass distributions obtained through weak-lensing and X-ray emission are strikingly similar, having nearly circular geometry. We suggest that Abell 586 is probably a truly relaxed cluster, whose last major merger occurred more than sim 4 Gyr ago