Spitzer Space Telescope - General Observer Proposal #80134


Measuring Mass In The WFC3 Infrared Spectroscopic Parallels Survey

Principal Investigator: James Colbert
           Institution: Spitzer Science Center

     Technical Contact: James Colbert, Spitzer Science Center

Co-Investigators: 
Harry Teplitz, Spitzer Science Center                                 
Claudia Scarlata, University of Minnesota                             
Brian Siana, Caltech                                                  
Matt Malkan, UCLA                                                     
Patrick McCarthy, Carnegie                                            
Alaina Henry, UCSB                                                    
Hakim Atek, SSC                                                       
Robert Fosbury, ESO                                                   
Nathanial Ross, UCLA                                                  
Nimish Hathi, Carnegie                                                
Carrie Bridge, Caltech                                                
Andrew Bunker, Oxford                                                 
Alan Dressler, Carnegie                                               
Hyunjin Shim, SSC                                                     

Science Category: high-z galaxies (z>0.5) 
 Observing Modes: IRAC Post-Cryo Mapping
  Hours Approved: 39.4 

Abstract:
The WFC3 Infrared Spectroscopic Parallel (WISP) Survey is using 500 HST orbits
to study the epoch of peak star formation. Its slitless grism spectroscopy over
a wide, continuous spectral range (0.8-1.7 micron) provides an unbiased
selection of thousands of emission?line galaxies over 0.5 < z < 2.5. Hundreds of
these galaxies are detected in multiple emission lines, allowing for important
diagnostics of metallicity and dust extinction. We propose deep 3.6 micron
imaging (5 sigma, 0.9 micro-Jy) of all 62 of the WISP fields observed with the
combination of G102+G141 grisms, in order to detect emission-line galaxies down
to 0.1 L*. Combined with our optical and near?IR photometry, these IRAC data
will be critical to determining accurate stellar masses for both passive and
active galaxies in our survey. We will determine the evolution of the faint end
slope of the stellar mass function and the mass-metallicity relation down to
low-mass galaxies, including measurement of a possible mass-metallicity-SFR
fundamental plane. The addition of the IRAC photometry will also provide much
stronger constraints on dust extinction and star formation history, especially
when combined with information available from the emission lines themselves.
Finally, it will also allow us to constrain the properties of stellar
populations in luminous z>6 Lyman alpha-emitters.