Decreased Specific Star Formation Rates in AGN Host Galaxies
  We investigate the location of an ultra-hard X-ray selected sample of AGN
from the Swift Burst Alert Telescope (BAT) catalog with respect to the main
sequence (MS) of star-forming galaxies using Herschel-based measurements of the
star formation rate (SFR) and stellar mass (\mstar) from Sloan Digital Sky
Survey (SDSS) photometry where the AGN contribution has been carefully removed.
We construct the MS with galaxies from the Herschel Reference Survey and
Herschel Stripe 82 Survey using the exact same methods to measure the SFR and
\mstar{} as the Swift/BAT AGN. We find a large fraction of the Swift/BAT AGN
lie below the MS indicating decreased specific SFR (sSFR) compared to non-AGN
galaxies. The Swift/BAT AGN are then compared to a high-mass galaxy sample
(COLD GASS), where we find a similarity between the AGN in COLD GASS and the
Swift/BAT AGN. Both samples of AGN lie firmly between star-forming galaxies on
the MS and quiescent galaxies far below the MS. However, we find no
relationship between the X-ray luminosity and distance from the MS. While the
morphological distribution of the BAT AGN is more similar to star-forming
galaxies, the sSFR of each morphology is more similar to the COLD GASS AGN. The
merger fraction in the BAT AGN is much higher than the COLD GASS AGN and
star-forming galaxies and is related to distance from the MS. These results
support a model in which bright AGN tend to be in high mass star-forming
galaxies in the process of quenching which eventually starves the supermassive
black hole itself.
