Tracing the cosmic growth of super massive black holes to z ~ 3 with
  Herschel
  We study a sample of Herschel-PACS selected galaxies within the GOODS-South
and the COSMOS fields in the framework of the PACS Evolutionary Probe (PEP)
project. Starting from the rich multi-wavelength photometric data-sets
available in both fields, we perform a broad-band Spectral Energy Distribution
(SED) decomposition to disentangle the possible active galactic nucleus (AGN)
contribution from that related to the host galaxy. We find that 37 per cent of
the Herschel-selected sample shows signatures of nuclear activity at the 99 per
cent confidence level. The probability to reveal AGN activity increases for
bright ($L_{\rm 1-1000} > 10^{11} \rm L_{\odot}$) star-forming galaxies at
$z>0.3$, becoming about 80 per cent for the brightest ($L_{\rm 1-1000} >
10^{12} \rm L_{\odot}$) infrared (IR) galaxies at $z \geq 1$. Finally, we
reconstruct the AGN bolometric luminosity function and the super-massive black
hole growth rate across cosmic time up to $z \sim 3$ from a Far-Infrared (FIR)
perspective. This work shows general agreement with most of the panchromatic
estimates from the literature, with the global black hole growth peaking at $z
\sim 2$ and reproducing the observed local black hole mass density with
consistent values of the radiative efficiency $\epsilon_{\rm rad}$
($\sim$0.07).
