Spitzer Space Telescope - Directors Discretionary Time Proposal #1096


Dust in ULIRG environments

Principal Investigator: Henrick Spoon
           Institution: Cornell University

Science Category: ULIRGS/LIRGS/HLIRGS 
 Observing Modes: IrsStare 
  Hours Approved: 10.0 

Abstract:
ISO spectroscopy has revealed that the spectra of ULIRGs are not
simply an ultra-luminous blend of AGN and starburst spectra.  Instead,
the 5-15 micron spectra show clear signs of ice and silicate
absorption features, which distort their mid-infrared spectra.
Especially puzzling are the 'modified' PAH emission features seen in
the ISO-CAM-CVF spectra of the more luminous and distant ULIRGs.  We
propose to study the effects of ice and silicate absorption on the
spectra of ULIRGs from the Tran et al.  ISO ("ZZ-ULIRG") sample.  This
sample is supplemented with less luminous galaxies, which ISO has
shown to be very dusty.  Our goal is to obtain full low-res spectra
for the complete sample and full high-res spectra for most of them.