ChandraReveals Galaxy Cluster with the Most Massive Nearby Cooling Core: RXC J1504.1−0248

Abstract

A Chandra follow-up observation of an X-ray-luminous galaxy cluster with a compact appearance, RXC J1504.1-0248, discovered in our REFLEX Cluster Survey, reveals an object with one of the most prominent cluster cooling cores. A β-model fit to the X-ray surface brightness profile gives a core radius of ~30 h kpc, which is much smaller than the cooling radius with ~140 kpc. As a consequence, more than 70% of the high X-ray luminosity of Lbol = 4.3 × 1045 h ergs s-1 of this cluster is radiated inside the cooling radius. A simple modeling of the X-ray morphology of the cluster leads to a formal mass deposition rate within the classical cooling flow model of 1500-1900 M☉ yr-1 (for h100 = 0.7; 2300-3000 M☉ yr-1 for h100 = 0.5). The center of the cluster is marked by a giant elliptical galaxy, which is also a known radio source. Thus, it is very likely that we are observing one of the interaction systems where the central cluster active galactic nucleus (AGN) is heating the cooling core region in a self-regulated way to prevent a massive cooling of the gas, similar to several such cases studied in detail in more nearby clusters. The interest raised by this system is then due to the high power recycled in RXC J1504-0248 over cooling timescales, which is about 1 order of magnitude higher than what occurs in the studied, nearby cooling core clusters. The assumption that cooling is exactly balanced by the AGN heating implies a central black hole mass growth rate of the order of 0.5 M☉ yr-1. This cluster is therefore a prime target for the study of AGN-intracluster medium interaction at very extreme conditions. Further features common to cooling cores found in this cluster are a strong temperature drop toward the center and narrow, low-ionization emission lines in the central cluster galaxy. The cluster is also found to be very massive, with a global X-ray temperature of about 10.5 keV and a total mass of about 1.7 × 1015 h M☉ inside 3 h Mpc.