AGN luminosity and stellar age -- two missing ingredients for AGN
  unification as seen with iPTF supernovae
  Active Galactic Nuclei (AGN) are extremely powerful cosmic objects, driven by
accretion of hot gas upon super-massive black holes. The zoo of AGN classes are
divided into two major groups, with Type-1 AGN displaying broad Balmer emission
lines and Type-2 narrow ones. For a long time it was believed that a Type-2 AGN
is a Type-1 AGN viewed through a dusty kiloparsec-size torus, but an emerging
body of observations suggests more than just the viewing angle matters. Here we
report significant differences in supernova counts and classes in the first
study to date of supernovae near Type-1 and Type-2 AGN host galaxies, using
data from the intermediate Palomar Transient Factory, the Sloan Digital Sky
Survey Data Release 7 and Galaxy Zoo. We detect many more supernovae in Type-2
AGN hosts (size of effect $\sim$ 5.1$\sigma$) compared to Type-1 hosts, which
shows that the two classes of AGN are located inside host galaxies with
different properties. In addition, Type-1 and Type-2 AGN that are dominated by
star formation according to WISE colours $m_{W1} - m_{W2} < 0.5$ and are
matched in 22 $\mu$m absolute magnitude differ by a factor of ten in
$L$[OIII]$\lambda$5007 luminosity, suggesting that when residing in similar
type of host galaxies Type-1 AGN are much more luminous. Our results
demonstrate two more factors that play an important role in completing the
current picture: the age of stellar populations and the AGN luminosity. This
has immediate consequences for understanding the many AGN classes and galaxy
evolution.
