Imaging a Cluster of Galaxies at Redshift 2.38

Abstract

We have discovered 8 galaxies at redshift 2.38, forming what we believe to be a rich galaxy cluster in the early stages of formation. A sub-set of 4 galaxies within the cluster form a very compact {< 100 kpc} galaxy group and may be merging to form a giant elliptical galaxy. This proto- elliptical is embedded in an extended, Ly-Alpha emitting, lumpy cloud of gas and dust, which is probably responsible for a complex of Lyman-limit absorption systems in the spectrum of a background QSO. We propose to image the cluster both in broad-band colours and in Ly-Alpha. These images will allow us to search for compact starbursts, which we hypothesise are responsible for the presence of dust in the extended gaseous cloud surrounding the proto-elliptical. The detailed morphology of the Ly-Alpha emission will tell us about the distribution of dust and gas, and their interaction with the stellar population. The colours, sizes and morphologies of the galaxies will give us a picture of n ew-born cluster ellipticals. Show more