Spitzer Space Telescope - General Observer Proposal #3406


Intermediate Aged Stars at Very High Redshifts:  Constraining the
Progeny of the Sources Responsible for Re-Ionization

Principal Investigator: Malcolm Bremer
           Institution: Bristol University

Co-Investigators: 
Matthew Lehnert, MPE                                                  
Aprajita Verma, MPE                                                   
Laura Douglas, Bristol University                                     

Science Category: high-z galaxies (z>0.5) 
 Observing Modes: IracMap 
  Hours Approved: 13.0 

Abstract:
We wish to image fields containing more than 20  spectroscopically
confirmed z>5 galaxies in the 3.6, 4.5, 5.8 and 8.0  micron bands.
When combined with our existing extremely deep optical data on the
fields we can determine the complete observed SEDs of the sources to
4.5 microns, and possibly to 8 microns.  Using these SEDs we can
determine approximate star formation histories for these sources.  If
they are shown to have undergone bursts or extended periods of star
formation to z>10, then this gives strong support for an extended or
multiple reionization of the Universe.  Non-detections will mean that
these sources are undergoing their first burst of star formation at
z<6,and cannot have contributed to any very early period of
reionization.