Ongoing Star Formation In AGN Host Galaxy Disks: A View From
  Core-collapse Supernovae
  The normalized radial distribution of young stellar populations (and cold
gas) in nearby galactic disks is compared between AGN host galaxies and
starforming galaxies (both with Hubble types between S0/a and Scd) by using
type II supernovae (SNe) as tracers. A subset of 140 SNe\,II with available
supernova position measurements are selected from the SAI-SDSS image catalog by
requiring available SDSS spectroscopy data of their host galaxies. Our sample
is finally composed of 46 AGNs and 94 starforming galaxies. Both directly
measured number distributions and inferred surface density distributions
indicate that a) the SNe detected in starforming galaxies follow an exponential
law well; b) by contrast, the SNe detected in AGN host galaxies significantly
deviate from an exponential law, which is independent of both morphological
type and redshift. Specifically, we find a detection deficit around
$R_{\mathrm{SN}}/R_{25,\mathrm{cor}}\sim0.5$ and an over-detection at outer
region $R_{\mathrm{SN}}/R_{25,\mathrm{cor}}\sim0.6-0.8$. This finding provides
a piece of evidence supporting that there is a link between ongoing star
formation (and cold gas reservoir) taking place in the extended disk and
central AGN activity.
