The connection between star formation and supermassive Black Hole
  activity in the local Universe
  We present a study of the active galactic nucleus (AGN) activity in the local
Universe (z < 0.33) and its correlation with the host galaxy properties,
derived from a Sloan Digital Sky Survey (SDSS DR8) sample with spectroscopic
star-formation rate (SFR) and stellar mass ($\mathcal{M}_{\ast}$)
determination. To quantify the level of AGN activity we used X-ray information
from the XMM-Newton Serendipitous Source Catalogue (3XMM DR8). Applying
multiwavelength AGN selection criteria (optical BPT-diagrams, X-ray/optical
ratio etc) we found that 24% of the detected sources are efficiently-accreting
AGN with moderate-to-high X-ray luminosity, which are twice as likely to be
hosted by star-forming galaxies than by quiescent ones. The distribution of the
specific Black Hole accretion rate (sBHAR, $\lambda_{\mathrm{sBHAR}}$) shows
that nuclear activity in local, non-AGN dominated galaxies peaks at very low
accretion rates ($-4 \lesssim \log\lambda_{\mathrm{sBHAR}} \lesssim -3$) in all
stellar mass ranges. However, we observe systematically larger values of sBHAR
for galaxies with active star-formation than for quiescent ones, as well as an
increase of the mean $\lambda_{\mathrm{sBHAR}}$ with SFR for both star-forming
and quiescent galaxies. These findings confirm the decreased level of AGN
activity with cosmic time and are consistent with a scenario where both
star-formation and AGN activity are fuelled by a common gas reservoir.
