Spitzer Space Telescope - General Observer Proposal #20193


IRS Spectral Mapping of Major Mergers

Principal Investigator: Lee Armus
           Institution: IPAC

Co-Investigators: 
J.D. Smith, University of Arizona                                     
Vassilis Charmandaris, University of Crete                            
John Hibbard, NRAO                                                    
Min Yun, University of Massachusetts                                  
Berhard Brandl, University of Leiden                                  
Jason Surace, SSC                                                     
Seppo Laine, SSC                                                      
Francois Schweizer, OCIW                                              
Tom Jarrett, IPAC                                                     
Aaron Evans, SUNY Stony Brook                                         

Science Category: interacting/merging galaxies 
 Observing Modes: IrsMap 
  Hours Approved: 44.9 

Abstract:
Interactions and mergers are important drivers of galaxy evolution.
Minor mergers can puff-up galactic disks, produce bars and rings, and
facilitate on-going star-formation through delivery of fresh fuel to
the parent galaxy.  Major mergers, those between more or less equal
mass galaxies, can completely disrupt the stellar and gaseous
morphologies of both systems, transform spirals into massive
ellipticals, and fuel both powerful starbursts and massive nuclear
black holes.  At high redshifts, mergers are responsible for the rapid
rise in the number counts seen in deep imaging surveys, and the
genesis of some of the most luminous galaxies observed.  We propose to
use the IRS on Spitzer in spectral mapping mode to study both the
morphology and the spectral properties of the gas and dust in a sample
of eight nearby, IR bright merging galaxies that span the range from
early (NGC 4676, NGC 6621, and NGC 7592) to mid (NGC 2623, NGC 520
and NGC 6240) to late (NGC 3921 and NGC 7252) major mergers.  With
these data we will be able to measure the spatial variations and
evolution in the hot and warm dust, search for buried AGN, and
directly couple the dust and ionized gas properties, even in regions
that are complete opaque in the optical.