Environments and morphologies of red sequence galaxies with residual star formation in massive clusters

Abstract

We present a photometric investigation into recent star formation in galaxy clusters at z ~ 0.1. We use spectral energy distribution templates to quantify recent star formation in large Xray- selected clusters from the LARCS survey using matched GALEX near-ultraviolet (NUV) photometry. These clusters all have signs of red sequence galaxy recent star formation (as indicated by the blue NUV - R colour), regardless of the cluster morphology and size. A trend in environment is found for these galaxies, such that they prefer to occupy low-density, highcluster- radius environments. The morphology of these UV-bright galaxies suggests that they are in fact red spirals, which we confirm with light profiles and Galaxy Zoo voting percentages as morphological proxies. These UV-bright galaxies are therefore seen to be either truncated spiral galaxies, caught by ram pressure infalling into the cluster, or high-mass spirals, with the photometry dominated by the older stellar population. © 2013 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.