Ultra-deep catalog of X-ray groups in the Extended Chandra Deep Field South

TL;DR

This paper presents an ultra-deep X-ray survey in the ECDF-S, cataloging 46 galaxy groups up to redshift 1.6, and analyzes their properties and mass relations using X-ray, optical, and lensing data.

Contribution

It provides the deepest X-ray group catalog in ECDF-S, extending the understanding of low-mass, high-redshift groups and validating scaling relations across different surveys.

Findings

Catalog of 46 X-ray groups up to z=1.6.

Consistency of ECDF-S properties with LCDM.

Weak lensing confirms low-mass nature of detected groups.

Abstract

Ultra-deep observations of ECDF-S with Chandra and XMM-Newton enable a search for extended X-ray emission down to an unprecedented flux of $2\times10^{-16}$ ergs s$^{-1}$ cm$^{-2}$. We present the search for the extended emission on spatial scales of 32$^{\prime\prime}$ in both Chandra and XMM data, covering 0.3 square degrees and model the extended emission on scales of arcminutes. We present a catalog of 46 spectroscopically identified groups, reaching a redshift of 1.6. We show that the statistical properties of ECDF-S, such as logN-logS and X-ray luminosity function are broadly consistent with LCDM, with the exception that dn/dz/d$\Omega$ test reveals that a redshift range of $0.2<z<0.5$ in ECDF-S is sparsely populated. The lack of nearby structure, however, makes studies of high-redshift groups particularly easier both in X-rays and lensing, due to a lower level of clustered foreground. We present one and two point statistics of the galaxy groups as well as weak-lensing analysis to show that the detected low-luminosity systems are indeed low-mass systems. We verify the applicability of the scaling relations between the X-ray luminosity and the total mass of the group, derived for the COSMOS survey to lower masses and higher redshifts probed by ECDF-S by means of stacked weak lensing and clustering analysis, constraining any possible departures to be within 30% in mass. Abridged.