AGN radiative feedback in the early growth of massive black holes
  Growing observational evidence confirms the existence of massive black holes
($M_{BH} \sim 10^9 M_{\odot}$), accreting at rates close to the Eddington
limit, at very high redshifts ($z \gtrsim 6-7$) in the early Universe. Recent
observations indicate that the host galaxies of the first quasars are
chemically evolved systems, containing unexpectedly large amounts of dust. Such
a combination of high luminosities and large dust content should form
favourable physical conditions for radiative dusty feedback. We explore the
impact of the active galactic nucleus (AGN) feedback, driven by radiation
pressure on dust, on the early growth of massive black holes. Assuming
Eddington-limited exponential black hole growth, we find that the dynamics and
energetics of the radiation pressure-driven outflows also follow exponential
trends at late times. We obtain modest outflow energetics (with momentum flux
$\dot{p} \lesssim L/c$ and kinetic power $\dot{E}_{k} \lesssim 10^{-3} L$),
comparable with available observations of quasar-driven outflows at very high
redshifts, but significantly lower than typically observed in local quasars and
predicted by wind energy-driven models. AGN radiative dusty feedback may thus
play an important role in powering galactic outflows in the first quasars in
the early Universe.
