Spitzer Space Telescope - General Observer Proposal #20525


Which FR-I Radio Galaxies Host Broad-Line Radio Galaxies or Quasars?

Principal Investigator: Robert Antonucci
           Institution: University of California, Santa Barbara

Co-Investigators: 
David Whysong, University of California, Santa Barbara                
Pat Ogle, NASA Jet Propulsion Laboratory                              
Makoto Kishimoto, University of Edinburgh                             

Science Category: AGN/quasars/radio galaxies 
 Observing Modes: IrsStare 
  Hours Approved: 40.1 

Abstract:
According to the simplest Unified Model, all radio galaxies contain
hidden quasars surrounded by opaque dusty tori.  In that case all
radio galaxies should produce strong reprocessed IR emission from the
obscuring tori.  We've shown with Keck mid-IR imaging and the first of
our Cycle 1 data on FR II radio galaxies that this is false:  while
all of the most luminous FR IIs have hidden broad line radio galaxies
or quasars, only SOME of the FR IIs at lower luminosity have them!
Here we propose to test the FR Is in a similar way.  Contrary to
popular belief, many of those DO have visible or hidden broad-line
nuclei.  By identifying which are which, we can infer the probably
energy source for each.  If a hidden broad line radio galaxy, most of
the power is though to come from accretion and most of their
luminosity is radiative;  otherwise by default probably most of the
power comes from black hole rotation and emerges in the form of the
the kinetic luminosity of the radio jet.  This difference is likely to
be manifest in the detailed radio source properties.  We will also
look for AGN narrow emission lines, and compare our spectra with dusty
torus models.