Detecting Star Formation in Brightest Cluster Galaxies with GALEX

TL;DR

This study uses GALEX UV observations to detect and analyze star formation in brightest cluster galaxies within cool core clusters, revealing correlations with cluster properties and dust attenuation.

Contribution

First comprehensive UV analysis of BCGs in cool core clusters showing star formation linked to cooling gas and cluster properties.

Findings

UV detection of star formation in BCGs up to z≥0.45

Correlation between UV excess and cluster cooling properties

Moderate-to-high dust attenuation in star-forming regions

Abstract

We present the results of GALEX observations of 17 cool core (CC) clusters of galaxies. We show that GALEX is easily capable of detecting star formation in brightest cluster galaxies (BCGs) out to $z\ge 0.45$ and 50-100 kpc. In most of the CC clusters studied, we find significant UV luminosity excesses and colors that strongly suggest recent and/or current star formation. The BCGs are found to have blue UV colors in the center that become increasingly redder with radius, indicating that the UV signature of star formation is most easily detected in the central regions. Our findings show good agreement between UV star formation rates and estimates based on H$\alpha$ observations. IR observations coupled with our data indicate moderate-to-high dust attenuation. Comparisons between our UV results and the X-ray properties of our sample suggest clear correlations between UV excess, cluster entropy, and central cooling time, confirming that the star formation is directly and incontrovertibly related to the cooling gas.