Richness-based masses of rich and famous galaxy clusters^⋆,⋆⋆

INAF–Osservatorio Astronomico di Brera, via Brera 28, 20121 Milano, Italy
e-mail: stefano.andreon@brera.inaf.it

Accepted: 29 June 2015Received: 13 January 2016

Abstract

We present a catalog of galaxy cluster masses derived by exploiting the tight correlation between mass and richness, i.e., a properly computed number of bright cluster galaxies. The richness definition adopted in this work is properly calibrated, shows a small scatter with mass, and has a known evolution, which means that we can estimate accurate (0.16 dex) masses more precisely than by adopting any other richness estimates or X-ray or SZ-based proxies based on survey data. We measured a few hundred galaxy clusters at 0.05 < z < 0.22 in the low-extinction part of the Sloan Digital Sky Survey footprint that are in the 2015 catalog of Planck-detected clusters, that have a known X-ray emission, that are in the Abell catalog, or that are among the most most cited in the literature. Diagnostic plots and direct images of clusters are individually inspected and we improved cluster centers and, when needed, we revised redshifts. Whenever possible, we also checked for indications of contamination from other clusters on the line of sight, and found ten such cases. All this information, with the derived cluster mass values, are included in the distributed value-added cluster catalog of the 275 clusters with a derived mass larger than 10¹⁴M_⊙. Finally, in a technical appendix we illustrate with Planck clusters how to minimize the sensitivity of comparisons between masses listed in different catalogs to the specific overlapping of the considerd subsamples, a problem recognized but not solved in the literature.