Chandra Follow-Up of the SDSS DR8 redMaPPer Catalog Using the MATCha Pipeline

TL;DR

This paper introduces the MATCha pipeline for analyzing archival Chandra X-ray data of galaxy clusters, enabling the study of their properties and scaling relations with optical surveys like SDSS redMaPPer.

Contribution

The paper presents the development and application of the MATCha pipeline to analyze X-ray properties of clusters from the SDSS redMaPPer catalog, revealing scaling relations and centering offsets.

Findings

Detected 447 clusters and measured 246 temperatures.

Found a scaling relation between temperature and optical richness.

Identified the distribution of X-ray and optical center offsets.

Abstract

In order to place constraints on cosmology through optical surveys of galaxy clusters, one must first understand the properties of those clusters. To this end, we introduce the Mass Analysis Tool for Chandra (MATCha), a pipeline which uses a parallellized algorithm to analyze archival Chandra data. MATCha simultaneously calculates X-ray temperatures and luminosities and performs centering measurements for hundreds of potential galaxy clusters using archival X-ray exposures. We run MATCha on the redMaPPer SDSS DR8 cluster catalog and use MATCha's output X-ray temperatures and luminosities to analyze the galaxy cluster temperature-richness, luminosity-richness, luminosity-temperature, and temperature-luminosity scaling relations. We detect 447 clusters and determine 246 r2500 temperatures across all redshifts. Within 0.1 < z < 0.35 we find that r2500 Tx scales with optical richness as ln(kB Tx / 1.0 keV) = (0.52 \pm 0.05) ln({\lambda}/70) + (1.85 \pm 0.03) with intrinsic scatter of 0.27 \pm 0.02 (1 {\sigma}). We investigate the distribution of offsets between the X-ray center and redMaPPer center within 0.1 < z < 0.35, finding that 68.3 \pm 6.5% of clusters are well-centered. However, we find a broad tail of large offsets in this distribution, and we explore some of the causes of redMaPPer miscentering.