Astrophysics Luncheon Seminar
How to Build a Cluster: The Formation of Massive Cluster Galaxies as Revealed by the Clusters Around Radio-Loud AGN (CARLA) Survey
Presented by Elizabeth Cooke
School of Physics and Astronomy, Unversity of Nottingham, UK
Monday, April 13, 2015
12:00 noon in 169-336
High redshift galaxy protoclusters are the precursors of today's massive clusters; the sites of formation of the most massive galaxies in the present-day Universe. In this talk I will examine the formation history of massive galaxies within high redshift protoclusters. We have obtained a sample of 37 dense clusters and protoclusters at 1.32. Taking the full cluster population into account, I will show that the formation of stars within the majority of massive cluster galaxies occurs over at least 2 Gyr, and peaks at z~2-3. From the average i' – [3.6] colours I will show that the star formation in these massive galaxies must have been rapidly terminated to produce the observed red colours. Finally, I will show that massive galaxies at z>2 must have assembled within 0.5 Gyr of them forming a significant fraction of their stars. This means that the formation mechanism of massive galaxies in clusters is redshift dependent: at z>2, few massive galaxies formed via dry mergers, whereas at z<2 dry merging is a more important formation mechanism.
JPL Contact: Daniel Stern (4-7264)