Deep Chandra Observations of the z = 1.16 Relaxed, Cool-core Galaxy Cluster SPT-CL J2215-3537

TL;DR

This paper presents deep Chandra X-ray observations of the high-redshift galaxy cluster SPT-CL J2215-3537 at z=1.16, providing insights into its mass, thermodynamics, and evolution as a relaxed, cool-core cluster.

Contribution

It reports the discovery and detailed analysis of the second most distant relaxed, cool-core galaxy cluster, offering valuable data on cluster formation and evolution at high redshift.

Findings

Constraints on the cluster's mass profile and thermodynamic properties.

Identification of a cool core and metal enrichment in the cluster.

Comparison with lower-redshift relaxed clusters to understand evolution.

Abstract

Galaxy clusters serve as a unique and valuable laboratory for probing cosmological models and understanding astrophysics at the high-mass limit of structure formation. Clusters that are dynamically relaxed are especially useful targets of study because of their morphological and dynamical simplicity. However, at redshifts z > 1, very few such clusters have been identified. We present results from new Chandra observations of the cluster SPT-CL J2215-3537 (hereafter SPT J2215), at z = 1.16, the second most distant relaxed, cool-core cluster identified to date. We place constraints on the cluster's total mass profile and investigate its thermodynamic profiles, scaling relations (gas mass, average temperature, and X-ray luminosity), and metal enrichment, resolving the cool core and providing essential context for the massive starburst seen in its central galaxy. We contextualize the thermodynamic and cosmological properties of the cluster within a sample of well-studied, lower-redshift relaxed systems. In this way, SPT J2215 serves as a powerful high-redshift benchmark for understanding the formation of cool cores and the evolution of massive clusters of galaxies.