Groups of Galaxies at Intermediate Redshift

TL;DR

This study investigates intermediate-redshift galaxy groups using X-ray observations to understand their properties, evolution, and connection to optical data, significantly expanding the sample of well-characterized groups at this redshift.

Contribution

It presents deep X-ray follow-up observations of 10 galaxy groups at intermediate redshift, nearly tripling the known sample with measured temperatures and luminosities.

Findings

All observed targets are confirmed as diffuse, thermal X-ray sources.

Derived temperatures and luminosities indicate these are rich groups or poor clusters.

The results help constrain non-gravitational effects on intragroup medium energetics.

Abstract

Galaxy groups are key tracers of galaxy evolution, cluster evolution, and structure formation, yet they are difficult to study at even moderate redshift. We have undertaken a project to observe a flux-limited sample of intermediate-redshift (0.1 < z < 0.5) group candidates identified by the XBootes Chandra survey. When complete, this project will nearly triple the current number of groups with measured temperatures in this redshift range. Here we present deep Suzaku/XIS and Chandra/ACIS follow-up observations of the first 10 targets in this project; all are confirmed sources of diffuse, thermal emission with derived temperatures and luminosities indicative of rich groups/poor clusters. By exploiting the multi-wavelength coverage of the XBootes/NOAO Deep Wide Field Survey (NDWFS) field, we aim to (1) constrain non-gravitational effects that alter the energetics of the intragroup medium, and (2) understand the physical connection between the X-ray and optical properties of groups. We discuss the properties of the current group sample in the context of observed cluster scaling relations and group and cluster evolution and outline the future plans for this project.