Spitzer Space Telescope - Directors Discretionary Time Proposal #268


Star Formation in High Redshift Clusters with Spitzer

Principal Investigator: John Blackwell
           Institution: Grainer Observatory, Phillips Exeter Academy

Co-Investigators: 
Velvet Dowdy, Graves County High School                               
Rosa Hemphill, Oregon Espiscopal School                               
Ardis Herrold, Grosse Pointe North High School                        
Thomas Loughran, Saint Joseph's High School                           
Dwight Taylor, South Anchorage High School                            
Gregory Rudnick, NOAO                                                 
Rose Finn, Siena College                                              
Vandana Desai, Caltech                                                

Science Category: high-z galaxies (z>0.5) 
 Observing Modes: IracMap MipsPhot 
  Hours Approved: 2.5 

Abstract:
We propose to study the evolution of star formation in galaxy cluster
environments by making measurements at epochs between 0.54 < z < 0.63.
We will measure the integrated SFRs for three optically selected
galaxy clusters from the ESO Distant Cluster Survey (EDisCS) using
MIPS 24micron photometry.  We will measure total past SFRs, i.e.
stellar masses, from rest-frame near-infrared (near-IR) photometry
obtained with IRAC.  Two of the three galaxy clusters already have
IRAC data.  We propose taking new IRAC data for CL1232.5-1250  to
complete the set.  We have found that H_alpha-derived star-formation
rates depend on both cluster mass and redshift (Finn et al.  2004,
2005a), demonstrating the necessity of sampling a large range in mass
to disentangle evolutionary trends from trends in mass.  Our three
targeted clusters span the range in mass from near-group environment
to the most massive cluster in the EDisCS sample.  This mass range
fills the gaps in existing studies, which are dominated by studies of
field environments or of very massive clusters.