Spitzer Space Telescope - General Observer Proposal #30940


Tracing Star Formation History in RCS Galaxy Clusters

Principal Investigator: Erica Ellingson
           Institution: University of Colorado

Co-Investigators: 
Jessica Jones, U. Colorado                                            
Howard Yee, University of Toronto                                     
Tracy Webb, McGill University                                         
Mike Gladders, U. Chicago                                             
Yeong Loh, U. Colorado                                                
Amy Bender, U. Colorado                                               

Science Category: Galaxy Clusters and Groups 
 Observing Modes: MipsPhot 
  Hours Approved: 63.7 

Abstract:
We propose to obtain MIPS 24micron images for 48 clusters selected
from the Red-Sequence Cluster Survey to study the evolution of star
formation history and AGN fraction and their dependence on galaxy
environment.  The cluster sample contains relatively rich clusters
(50% with estimated richness richer than mid-Abell class 1), and
covers a large redshift range (0.3 to 1.1) uniformly.  Current studies
of star formation in mid-redshift suggest that a significant fraction
of star formation in clusters may be hidden by dust.  A statistically
robust census using a well-defined cluster sample will greatly improve
our understanding of galaxy evolution clusters and the role the
environment plays.  We will be able to measure star formation rate to
30  Msun/yr, for the overall sample, and to ~10-15Msun/yr for a
subsample of z~1 clusters.  The combination of the MIPS data and
allocated IRAC imaging of the same sample will allow us to disentangle
starburst/AGN sources.  We will derive the excess 24micron sources in
clusters as a function of redshift, study the spatial distribution of
dusty starbursts and AGN in clusters, and the dependence of these
activities on the properties of the clusters.  Furthermore, these
clusters have extensive ancillary follow-up data, including deep
4-color optical photometry, H or K band NIR imaging, multi-object
spectroscopy, HST-ACS images, and SCUBA and deep radio imaging,
allowing us to carry out detailed studies of the properties of
24micron luminous galaxies in clusters.