Modeling the Infrared Emission from Cygnus A
  The Spitzer Space Telescope provides a unique view of the Universe at
infrared wavelengths. Improved sensitivity and angular resolution over previous
missions enable detailed studies of astrophysical objects, both in imaging and
spectroscopic modes. Spitzer observations of active galactic nuclei can help
shed light on the physical conditions of the central regions of these active
glalaxies.
  The nearby radio galaxy Cygnus A is one of the most luminous radio sources in
the local Universe. In addition to the high radio power, it is also very
luminous in the infrared. New Spitzer spectroscopy and photometry of Cygnus A
is combined with data from the literature at radio and sub-mm wavelengths. The
resulting complication is modeled with a combination of: a synchrotron emitting
jet, a burst of star formation, and emission from an AGN torus.
  The infrared emission in Cyngus A shows contributions from all three
processes and the models are able to reproduce the observed emission over
almost 5 dex in frequency. The bolometric AGN luminosity is found to be ~10^45
erg s^-1, with a clumpy torus size of ~7 pc. Evidence is seen for a break in
the synchrotron spectrum in the mid-infrared. The relevant component of the
infrared emission suggests Cygnus A has a star formation rate of ~20 M_sun
yr^-1. Even in the absence of the AGN, it would still be a luminous infrared
source.
