Spitzer Space Telescope - General Observer Proposal #50310


Unveiling the Physics of the First Galaxies

Principal Investigator: Peter Capak
           Institution: Spitzer Science Center

     Technical Contact: Peter Capak, Spitzer Science Center

Co-Investigators: 
Bahram Mobasher, University of California, Riverside                  
Nick Scoville, Caltech                                                
Yoshi Tanaguchi, Ehime Univsersity                                    
Mara Salvato, Caltech                                                 
Dave Sanders, University of Hawaii                                    

Science Category: high-z galaxies (z>0.5) 
 Observing Modes: IracMap 
  Hours Approved: 46 

Abstract:
We propose to observe 92 spectroscopically confirmed 4.5<z<6 galaxies with IRAC
on Spitzer, providing an unprecedented census of massive galaxies and star
formation in the epoch of early structure formation and reionization. These
observations, combined with our existing data, will allow us to estimate the
mass, age, dust content of these objects. This sample represents a ~10 fold
increase in the number of objects at z>4.5 bright enough to study in detail
(Eyles et al. 2007; Yan et al. 2005) and the proposed observations are a factor
of 5 more efficient than blank field surveys for these bright objects due to
their low surface density. Very little is known about galaxies in this redshift
range because they are faint and relatively rare. Also, the region of the galaxy
Spectral Energy Distribution (SED) containing mass and age information is
redshifted to the near and mid infrared where it is more difficult to measure.
The proposed IRAC observations provide some of the key pieces of information
required to study these high redshift objects. This project complements the
extremely deep observations of z>5 galaxies in GOODS and UDF by probing the
bright end and knee of the luminosity function as well as probing a large enough
volume to reduce the effects of cosmic variance.