Spitzer Space Telescope - General Observer Proposal #3592


Spitzer Observations of the Highest-Redshift Gamma-Ray Bursts

Principal Investigator: Derek Fox
           Institution: Penn State University

Co-Investigators: 
Avishay Gal-Yam, California Institute of Technology                   
Alicia Soderberg, California Institute of Technology                  
Shri Kulkarni, California Institute of Technology                     
Edo Berger, California Institute of Technology                        
Brad Cenko, California Institute of Technology                        
Dae-Sik Moon, California Institute of Technology                      
Sarah Yost, California Institute of Technology                        
Fiona Harrison, California Institute of Technology                    
Dale Frail, National Radio Astronomy Observatory                      
Mario Hamuy, Observatories of the Carnegie Institution of Washi       
Steve Shectman, Observatories of the Carnegie Institution of Washi    
Eric Persson, Observatories of the Carnegie Institution of Washi      
Mark Phillips, Observatories of the Carnegie Institution of Washi     
Miguel Roth, Observatories of the Carnegie Institution of Washi       
Patrick McCarthy, Observatories of the Carnegie Institution of Washi  
Michael Rauch, Observatories of the Carnegie Institution of Washi     

Science Category: GRBs 
 Observing Modes:  
  Hours Approved: 23.4 

Abstract:
We propose to use the Spitzer Space Telescope to study the infrared
(3.6 to 8.0  micron) afterglow emission of GRBs from the 'dark ages'
of the universe, z>6.  Current theories of the early universe predict
the first star formation activity at z~20, and since GRBs are
associated with the deaths of massive stars they may be expected at
this epoch as well, before the formation of the first quasars.  Our
candidate high-redshift afterglows will be identified in ground-based
near-infrared imaging as objects with red J-K and H-K colors, J-K >
H-K > 3.0  mag.  For these bursts, 4-band IRAC imaging can provide the
crucial additional color information that will distinguish afterglows
at z>13 (H-band drop-outs) from those within high-extinction
environments at z>6 (rest-frame E_B-V>0.8).  We request time to carry
out two high-impact Spitzer TOO campaigns during the cycle.  The
confirmation of even a single z>6 burst will have immediate
implications for theories of the early universe, formation of the
first nonlinear structures, the nature of the earliest stars, and
cosmology.