Spitzer Space Telescope - General Observer Proposal #40640


The most extreme starbursts in the local Universe

Principal Investigator: Steve Croft
           Institution: University of California, Davis

     Technical Contact: Steve Croft, University of California, Davis

Co-Investigators: 
Wim de Vries, UC Davis                                                
Edward Laag, UC Riverside                                             
Gabriela Canalizo, UC Riverside                                       
Mark Lacy, JPL                                                        
Wil van Breugel, LLNL / UC Merced                                     
Bob Becker, UC Davis                                                  

Science Category: ULIRGS/LIRGS/HLIRGS 
 Observing Modes: MipsPhot 
  Hours Approved: 31.4 

Abstract:
We select galaxies with extreme star formation rates (SFR > 200 solar masses per
year) in a volume-limited (0.1 < z < 0.3) sample from the Brinchmann et al.
(2004) study of star-forming galaxies in the local Universe. Such galaxies are
predicted to have infrared (IR) luminosities greater than 10^12 solar
luminosities, and as such are the optically-selected counterparts to
ultraluminous infrared galaxies (ULIRGs). We propose to obtain MIPS 24, 70 and
160 micron observations of this sample to study the luminosities, SEDs, and dust
temperatures of the host galaxies, their merger companions, and other galaxies
in their environs. We will look for evidence (from SEDs) of hidden "Type 2" AGN,
and correlate merger fraction, merger stage (from optical images), and AGN
fraction with other properties such as IR luminosity and color. Trends within
the sample, as well as comparison with IR-selected ULIRGs, will shed light on
the evolutionary processes linking extreme star formation, AGN fueling, and the
fate of gas and dust in the mergers which are believed to lead to the formation
of large elliptical galaxies. The extreme SFRs in our sample are more familiar
from high-redshift systems such as sub-mm galaxies, Lyman break galaxies, and
distant radio galaxies. This is an excellent opportunity to study with
unprecedented detail and sensitivity the local analogs of these systems which
were so important in the evolution of galaxies in the early Universe.