Chandra Observation of 3C288 - Reheating the Cool Core of a 3 keV Cluster from a Nuclear Outburst at z = 0.246

TL;DR

This study uses Chandra X-ray observations to analyze the hot gas and shock features around the radio galaxy 3C288, revealing a recent nuclear outburst that reheated the cluster core and disrupted cool core conditions.

Contribution

It provides the first detailed analysis of shock-induced heating and core disruption caused by a nuclear outburst in a galaxy cluster at z=0.246.

Findings

Detection of 3 keV gas extending to 0.5 Mpc

Identification of surface brightness discontinuities as shocks

Energy of outburst estimated at ~10^60 ergs

Abstract

We present results from a 42 ks Chandra/ACIS-S observation of the transitional FRI/FRII radio galaxy 3C288 at z = 0.246. We detect $\sim$3 keV gas extending to a radius of $\sim$0.5 Mpc with a 0.5-2.0 keV luminosity of 6.6 $\times$ 10$^{43}$ ergs s$^{-1}$, implying that 3C288 lies at the center of a poor cluster. We find multiple surface brightness discontinuities in the gas indicative of either a shock driven by the inflation of the radio lobes or a recent merger event. The temperature across the discontinuities is roughly constant with no signature of a cool core, thus disfavoring either the merger cold-front or sloshing scenarios. We argue therefore that the discontinuities are shocks due to the supersonic inflation of the radio lobes. If they are shocks, the energy of the outburst is $\sim$10^{60} ergs, or roughly 30% of the thermal energy of the gas within the radius of the shock, assuming that the shocks are part of a front produced by a single outburst. The cooling time of the gas is $\sim$10^8 yrs, so that the energy deposited by the nuclear outburst could have reheated and efficiently disrupted a cool core.