Submillimetre observations of galaxy clusters with BLAST: the star-formation activity in Abell 3112

TL;DR

This study uses submillimetre observations from BLAST to analyze star-formation activity in the galaxy cluster Abell 3112, revealing the distribution and properties of star-forming galaxies within the cluster.

Contribution

First submillimetre survey of Abell 3112, providing insights into star formation distribution and properties of cluster galaxies at multiple wavelengths.

Findings

Detected five bright submillimetre cluster members with high-mass, star-forming characteristics.

Mean submillimetre emission peaks near the cluster's virialized boundary region.

Most submillimetre emission originates from intermediate-mass galaxies outside the giant ellipticals.

Abstract

We present observations at 250, 350, and 500 um of the nearby galaxy cluster Abell 3112 (z=0.075) carried out with BLAST, the Balloon-borne Large Aperture Submillimeter Telescope. Five cluster members are individually detected as bright submillimetre sources. Their far-infrared SEDs and optical colours identify them as normal star-forming galaxies of high mass, with globally evolved stellar populations. They all have B-R colours of 1.38+/-0.08, transitional between the blue, active population and the red, evolved galaxies that dominate the cluster core. We stack to determine the mean submillimetre emission from all cluster members, which is determined to be 16.6+/-2.5, 6.1+/-1.9, and 1.5+/-1.3 mJy at 250, 350, and 500 um, respectively. Stacking analyses of the submillimetre emission of cluster members reveal trends in the mean far-infrared luminosity with respect to cluster-centric radius and Ks-band magnitude. We find that a large fraction of submillimetre emission comes from the boundary of the inner, virialized region of the cluster, at cluster-centric distances around R_500. Stacking also shows that the bulk of the submillimetre emission arises in intermediate-mass galaxies (L<L*), with Ks magnitude ~1 mag fainter than the giant ellipticals. The results and constraints obtained in this work will provide a useful reference for the forthcoming surveys to be conducted on galaxy clusters by Herschel.