Spitzer Space Telescope - General Observer Proposal #20475


The Einstein Cross Quasar:  The Hottest Dust Around a Quasar in the
Universe?

Principal Investigator: Eric Agol
           Institution: University of Washington

Co-Investigators: 
Varoujan Gorjian, Jet Propulsion Laboratory                           
Amy Kimball, University of Washington                                 

Science Category: AGN/quasars/radio galaxies 
 Observing Modes: IracMap IrsStare 
  Hours Approved: 4.0 

Abstract:
The Einstein Cross radio-quiet quasar images show microlensing by
stars in the lens galaxy which allows constraints to be placed on the
size of the ultraviolet and infrared emission regions.  Preliminary
ground-based data indicates that this quasar has the hottest dust of
any known quasar.  We propose to measure the mid-infrared spectral
energy distribution with IRAC and IRS to determine whether most of the
dust emission comes from dust near the sublimation temperature.  In
addition, we will look for the presence of PAH features.  These
measurements, in conjunction with microlensing measurements, will
provide a probe of accretion disk physics, an indication of the dust
composition, and an estimate of the size of the infrared emission
region which can be used in simulations of lensing by dark matter
substructure.