Dust-enshrouded star formation in XMM-LSS galaxy clusters

TL;DR

This study investigates dust-enshrouded star formation in galaxy clusters across redshifts 0.05 to 1.05 using mid-IR data, revealing increased obscured activity at intermediate redshifts and specific cluster regions.

Contribution

It provides new insights into the distribution and density of obscured star-forming galaxies in clusters over a wide redshift range, highlighting the evolution of the Butcher-Oemler effect.

Findings

High numbers of bright 24um sources in intermediate redshift clusters.

Evidence of excess mid-IR sources at cluster-centric radii 200-500 kpc for z ≥ 0.4.

Presence of excess sources at larger radii in some cases.

Abstract

We present an investigation of the dust-enshrouded activity in a sample of X-ray selected clusters drawn from the XMM-LSS survey in the redshift range z ~ 0.05 - 1.05. By taking advantage of the contiguous mid-IR coverage of the XMM-LSS field by the Spitzer SWIRE legacy survey, we examined the distribution and number density of mid-IR bright sources out to the cluster periphery and its dependence on redshift to probe the obscured side of the Butcher-Oemler effect. Toward intermediate redshift clusters we identified surprisingly high numbers of bright 24um sources, whose photometric redshifts are compatible with cluster membership. The stacked surface density profile of 24um sources in clusters within four redshift bins gives evidence for an excess of bright mid-IR sources at redshift z $\geq$ 0.4 at cluster-centric radii ~ 200 - 500 kpc. Some traces of excess appear to be present at larger radii as well.