Accreting SMBHs in the COSMOS field and the connection to their host
  galaxies
  Using the wide multi-band photometry available in the COSMOS field we explore
the host galaxy properties of a large sample of Active Galactic Nuclei (AGN)
obtained by combining X-ray and optical spectroscopic selections. Based on a
careful study of their Spectral Energy Distribution (SED), which has been
parametrized using a 2-component (AGN+galaxy) model fit, we derived
dust-corrected rest-frame magnitudes, colors, stellar masses and star formation
rates (SFRs). We find that AGN hosts span a large range of stellar masses and
SFRs. No color-bimodality is seen at any redshift in the AGN hosts, which are
found to be mainly massive, red galaxies. Once accounting for the color-mass
degeneracy in well defined mass-matched samples, we find a residual marginal
enhancement of AGN incidence in redder galaxies with lower specific star
formation rates, and we argue that this result might emerge because of our
ability to properly account for AGN light contamination and dust extinction.
Interestingly, we find that the probability for a galaxy to host a black hole
growing at any given "specific accretion rate" (i.e. the ratio of X-ray
luminosity to the host stellar mass) is almost independent of the host galaxy
mass, while it decreases as a power-law with Lx/M. By analyzing the
normalization of such probability distribution, we show how the incidence of
AGN increases with redshift as rapidly as (1+z)^4, in close resemblance with
the overall evolution of the specific star formation rate of the entire galaxy
population. Although AGN activity and star formation in galaxies do appear to
have a common triggering mechanism, at least in a statistical sense, within the
COSMOS sample we do not find strong evidence of any 'smoking gun' signaling
powerful AGN influence on the star-forming properties of their hosts galaxies.
