The Massive and Distant Clusters of $WISE$ Survey. XII. Exploring X-ray AGN in Dynamically Active Massive Galaxy Clusters at z~1

TL;DR

This study investigates the relationship between X-ray morphology and AGN activity in z~1 galaxy clusters, revealing that disturbed clusters tend to host more AGN, with AGN density inversely related to cluster mass and influenced by dynamical state.

Contribution

It provides new evidence linking cluster dynamical disturbance to increased AGN activity and explores the mass dependence of AGN incidence in high-redshift clusters.

Findings

Disturbed clusters show higher AGN excess compared to relaxed ones.

AGN surface density inversely scales with cluster mass (~M^{-0.5}).

Tentative divergence in AGN trends between disturbed and relaxed clusters near outskirts.

Abstract

We present an analysis of the cluster X-ray morphology and active galactic nucleus (AGN) activity in nine $z\sim1$ galaxy clusters from the Massive and Distant Clusters of $WISE$ Survey (MaDCoWS) observed with $Chandra$. Using photon asymmetry ($A_{\text{phot}}$) to quantify X-ray morphologies, we find evidence that the four most dynamically disturbed clusters are likely to be mergers. Employing a luminosity cut of $7.6\times10^{42}$ erg/s to identify AGN in the 0.7-7.0 keV, we show that the majority of these clusters host excess AGN compared to the local field. We use the cumulative number-count ($\log N-\log S$) model to predict AGN incidence in cluster isophotes under this luminosity cut. Our analysis finds evidence (at $> 2\sigma$) of a positive correlation between AGN surface densities and photon asymmetry, suggesting that a disturbed cluster environment plays a pivotal role in regulating AGN triggering. Studying AGN incidence in cluster X-ray isophotes equivalent in area to $1.0r_{500}$, we find that the AGN space density inversely scales with cluster mass as $\sim M^{-0.5^{+0.18}_{-0.18}}$ at the 3.18$\sigma$ level. Finally, when we separately explore the cluster mass dependence of excess AGN surface density in disturbed and relaxed clusters, we see tentative evidence that the two morphologically distinct sub-populations exhibit diverging trends, especially near the outskirts, likely due to cluster merger-driven AGN triggering/suppression.