Spitzer Space Telescope - General Observer Proposal #50245


Evolution of IR-luminous SED from 0.1 < z < 0.6

Principal Investigator: Benjamin Bertincourt
           Institution: Institut d'Astrophysique Spatiale

     Technical Contact: Benjamin Bertincourt, Institut d'Astrophysique Spatiale

Co-Investigators: 
Guilaine Lagache, IAS, France                                         
Emeric Le Floc'h, University of Arizona, US                           
Christopher Willmer, University of Arizona, US                        
Casey Papovich, University of Arizona, US                             
Herve Dole, IAS, France                                               
Nicolas Bavouzet, IAS, France                                         
George Helou, IPAC / Caltech, US                                      
Jean-Loup Puget, IAS, France                                          
Francois Boulanger, IAS, France                                       

Science Category: intermediate-z galaxies (0.05<z<0.5) 
 Observing Modes: MipsPhot 
  Hours Approved: 17.1 

Abstract:
Luminous Infrared Galaxies (LIRGs) are primary contributors to the energy
production at redshift ~1. They are responsible for the dramatic increase of the
star formation density from z=0 to z=1. Establishing proper spectral energy
distribution for this class of sources to characterize the physics of the high
star formation activity is one of the challenge of the coming decade. We have
obtained IRS low resolution spectra of a sample of 40 LIRGs at 0.1<z<0.6. The
sample shows on average a strong evolution of PAH ratios and continuum emission
with redshift. However, the interpretation of the evolution is hampered by the
lack of precise determination of IR luminosity and dust temperature. We thus
request for deep MIPS 70 and 160 photometric data. With these new data we will
be able to place our measured mid-IR continuum, PAH strengths, and dust
temperature in a coherent physical model of SED (similar as in Dopita et al.
2005).