Inception of a first quasar at cosmic dawn
  Earliest quasars at the cosmic dawn are powered by mass accretion onto
supermassive black holes of a billion solar masses. Massive black hole seeds
forming through the direct collapse mechanism are considered the most promising
candidates but how do they grow and co-evolve with their host galaxies at early
cosmic times remains unknown. We here present results from a cosmological
radiation hydrodynamical simulation including self-consistent modeling of both
Pop III and Pop II star formation, their radiative and supernova feedback in
the host galaxy along with X-ray feedback from an accreting massive black hole
(MBH) of $\rm 10^5 ~M_{\odot}$ in a halo of $\rm 2 \times 10^9~M_{\odot}$ from
$z=26$ down to $z=16$. Our results show that energy deposition from X-rays in
the proximity of MBH suppresses Pop III star formation for about 12 Myr while
at the same time these X-rays catalyze $\rm H_2$ formation which leads to the
formation of a Pop III star cluster of 500 $\rm M_{\odot}$ in the close
vicinity of the MBH. We find that mode of star formation for Pop III is
episodic and bursty due to the clumpy accretion while for Pop II it is
continuous. The stellar mass of the host galaxy at $z \sim 16$ is $\rm 2 \times
10^7~M_{\odot}$ with a star formation rate (SFR) of $\rm \sim
0.1-1~M_{\odot}/yr$. In total, the MBH accretes $\rm 1.5 \times 10^6~M_{\odot}$
during 120 Myr with the mean accretion rate of $\rm \sim 0.01~M_{\odot}/yr$
corresponding to an average Eddington fraction of 50\%.
