The X-ray luminous cluster underlying the z = 1.04 quasar PKS1229-021

TL;DR

This study analyzes the extended X-ray emission around the high-redshift quasar PKS1229-021, revealing a cool core cluster with a luminosity of approximately 2 x 10^{44} erg/s, and discusses challenges in detecting such clusters at high redshift.

Contribution

First detailed X-ray analysis of a cool core cluster associated with a z=1.04 quasar, demonstrating methods to subtract quasar PSF and compare with similar radio galaxy profiles.

Findings

Extended X-ray emission traced to ~120 kpc

Presence of a cool core indicated by hardness ratio drop

Estimated cluster luminosity ~2 x 10^{44} erg/s

Abstract

We present a 100 ks Chandra observation studying the extended X-ray emission around the powerful z=1.04 quasar PKS1229-021. The diffuse cluster X-ray emission can be traced out to ~15 arcsec (~120 kpc) radius and there is a drop in the calculated hardness ratio inside the central 5 arcsec consistent with the presence of a cool core. Radio observations of the quasar show a strong core and a bright, one-sided jet leading to the SW hot spot and a second hot spot visible on the counter-jet side. Although the wings of the quasar PSF provided a significant contribution to the total X-ray flux at all radii where the extended cluster emission was detected, we were able to accurately subtract off the PSF emission using ChaRT and marx simulations. The resulting steep cluster surface brightness profile for PKS1229-021 appears similar to the profile for the FRII radio galaxy 3C444, which has a similarly rapid surface brightness drop caused by a powerful shock surrounding the radio lobes (Croston et al.). Using a model surface brightness profile based on 3C444, we estimated the total cluster luminosity for PKS1229-021 to be L_X ~ 2 x 10^{44} erg/s. We discuss the difficulty of detecting cool core clusters, which host bright X-ray sources, in high redshift surveys.