Gemini and Chandra observations of Abell 586, a relaxed strong-lensing cluster

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 Chandra space telescope. Employing different techniques - velocity distribution of galaxies, weak gravitational lensing, and spatially resolved X- ray 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 km s (-1). 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 similar to 4 Gyr ago.