* Astronomy

Title: Probing cluster dynamics in RXCJ1504.1-0248 via radial and two-dimensional gas and galaxy properties
Authors: Yu-Ying Zhang, Miguel Verdugo, Matthias Klein, Peter Schneider

We studied one of the most X-ray luminous cluster of galaxies in the REFLEX survey, RXC J1504.1-0248 (hereafter R1504; z=0.2153), using XMM-Newton X-ray imaging spectroscopy, VLT/VIMOS optical spectroscopy and WFI optical imaging. The mass distributions were determined using the hydrostatic method with X-ray imaging spectroscopy and dynamical method with optical spectroscopy, respectively, which yield M^{H.E.}_{500}=(5.81±0.49)*1.e14 solar masses and M^{caustic}_{500}=(4.17±0.42)*1e14 solar masses. According to recent calibrations the richness derived mass estimates agree well with the hydrostatic and dynamical mass estimates. The line-of-sight velocities of spectroscopic members reveal a high-velocity (>1000 km/s) group at a projected distance near r^{H.E.}_{500}=(1.18+/-0.03) Mpc south-east of the cluster centroid, which is also indicated in the X-ray two-dimensional (2-D) temperature, density, entropy and pressure maps. The dynamical mass estimate is 80% of the hydrostatic mass estimate at r^{H.E.}_{500}. It can be partially explained by the ~20% scatter in the 2-D pressure map that could be propagated in the hydrostatic mass estimate. The uncertainty of the dynamical mass estimate due to the substructure of the high-velocity group is ~14%. The dynamical mass estimate using blue members is 1.23 times of that using red members. The observed scaling relations of R1504 agree with those for nearby clusters although its stellar mass fraction is rather low.

Read more (493kb, PDF)

Position (J2000): R.A. 15 4 11.62  |  Dec. -2° 47' 30.12''