Probing cluster dynamics in RXC J1504.1-0248 via radial and two-dimensional gas and galaxy properties

¹ Argelander-Institut für Astronomie, Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany
e-mail: yyzhang@astro.uni-bonn.de
² Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße, 85748 Garching, Germany
³ University of Vienna, Department of Astronomy, Türkenschanzstraße 17, 1180 Vienna, Austria

Received: 7 February 2012
Accepted: 12 April 2012

Abstract

We study one of the most X-ray luminous cluster of galaxies in the REFLEX survey, RXC J1504.1-0248 (hereafter R1504; z_cl = 0.2153), using XMM-Newton X-ray imaging spectroscopy, VLT/VIMOS optical spectroscopy, and WFI optical imaging. The mass distributions were determined using both the so-called hydrostatic method with X-ray imaging spectroscopy and the dynamical method with optical spectroscopy, respectively, which yield M₅₀₀^H.E. = (5.81±0.49)×10¹⁴ M_⊙ and M₅₀₀^caustic = (4.17±0.42)×10¹⁴ M_⊙. According to recent calibrations, the richness-derived mass estimates closely agree with the hydrostatic and dynamical mass estimates. The line-of-sight velocities of spectroscopic members reveal a group of galaxies with high velocities (>1000 km s^-1) at a projected distance of about r₅₀₀^H.E. = (1.18±0.03) Mpc south-east of the cluster centroid, which is also indicated in the X-ray two-dimensional (2D) temperature, density, entropy, and pressure maps. The dynamical mass estimate is 80% of the hydrostatic mass estimate at r₅₀₀^H.E.. It can be partially explained by the  ~20% scatter in the 2D pressure map that can be propagated into the hydrostatic mass estimate. The uncertainty in the dynamical mass estimate caused by the substructure of the high velocity group is  ~14%. The dynamical mass estimate using blue members is 1.23 times that obtained using red members. The global properties of R1504 obey the observed scaling relations of nearby clusters, although its stellar-mass fraction is rather low.