Spitzer Space Telescope - General Observer Proposal #60112


A SURVEY OF CLUSTER-GROWTH AT EARLY EPOCHS

Principal Investigator: Nina Hatch
           Institution: Universiteit Leiden

     Technical Contact: Nina Hatch, Universiteit Leiden

Co-Investigators: 
Nick Seymour, MSSL, UCL, UK                                           
George Miley, Leiden Observatory, NL                                  
Carlos De Breuck, ESO                                                 
Tadayuki Kodama, Nat Astro Obs Japan                                  
Joel Vernet, ESO                                                      
Huub Rottgering, Leiden Observatory                                   
Audrey Galametz, ESO                                                  
Bram Venemans, ESO                                                    
Jaron Kurk, MPIA, Germany                                             
Alessandro Rettura, University of California, Davis                   
Masayuki Tanaka, ESO                                                  
Michelle Doherty, ESO                                                 

Science Category: galaxy clusters and groups(high-z) 
 Observing Modes: IRAC Post-Cryo Mapping
  Hours Approved: 28.9 

Abstract:
Forming clusters of galaxies, protoclusters, are unique laboratories for
studying galaxy evolution as they contain large numbers of galaxies in the same
rich environment. We propose to use Spitzer to study galaxy and cluster
evolution during the formative epoch of dense structures (1.7 < z < 3) by
observing a well-defined sample of 10 protocluster fields. These fields have
already been observed at shorter wavelengths (Y, J, H, K) using the new HAWK-I
wide-field imager on the VLT and form the first statistically significant sample
of evolved protocluster galaxies ( ~ 800 protocluster galaxy candidates). We
propose to obtain 3.6 and 4.5 micron data on the 10 fields in order to: (i)
distinguish between dusty starbursts and passively evolving galaxies; and (ii)
measure the masses of the protocluster galaxies. The Spitzer data will
facilitate population studies of high density environments, enabling us to
create the first mass-selected samples of galaxies in protoclusters at 1.7 < z <
3, and select H-alpha emitting starburst galaxies for spectroscopic follow-up.