Spitzer Space Telescope - Archive Research Proposal #50443


PRIMUS: stellar mass growth since z=1 with redshifts over 8 sq deg of SWIRE

Principal Investigator: Michael Blanton
           Institution: New York University

     Technical Contact: Michael Blanton, New York University

Co-Investigators: 
John Moustakas, New York University                                   
Daniel Eisenstein, University of Arizona                              
Alison Coil, University of Arizona                                    
Richard Cool, University of Arizona                                   
Adam Bolton, Institute for Astronomy, University of Hawaii            
David Hogg, New York University                                       

Science Category: high-z galaxies (z>0.5) 
Dollars Approved: 125000 

Abstract:
We propose here for archival research funding to measure the build-up of stellar
mass over the last eight billion years, using an unprecedentedly large sample.
Measuring the increase of stellar mass in galaxies, and determining its
dependence on galaxy type and environment, yields crucial information about the
star-formation and merger history of galaxies. This history has been the subject
of intense research over the past few years, but has been limited by both
systematic effects and by the sizes of the available observational samples. Our
PRIMUS survey contains over 200,000 spectroscopic redshifts, measured at 1
percent precision, out to redshift z=1, covering 8 square degrees of SWIRE and
S-COSMOS imaging. Our sample is flux-limited at i=23 and includes all galaxy
types, spanning the red and blue galaxy populations. We have created this sample
using a special mode we have developed for the IMACS instrument on the Magellan
6.5m at Las Campanas Observatories: a low dispersion prism in combination with a
multi-slit mask. This configuration allows redshift determination of 1 percent
accuracy, while also allowing extreme multiplexing to obtain over 2,000 galaxy
spectra simultaneously. With the SWIRE optical and infrared imaging in
combination with our redshift determinations, we can recover much more accurate
estimates of the stellar mass of each galaxy and construct a high
signal-to-noise estimate of the stellar mass function over a range of redshifts.
These measurements will dramatically improve our current understanding of the
build-up of stellar mass, both by decreasing the statistical uncertainty due to
sample variance with our massive sample, and by decreasing the systematic
uncertainties in stellar masses by using the SWIRE and S-COSMOS imaging.