The early growth of supermassive black holes in cosmological hydrodynamic simulations with constrained Gaussian realizations. (arXiv:1906.00242v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Huang_K/0/1/0/all/0/1">Kuan-Wei Huang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Feng_Y/0/1/0/all/0/1">Yu Feng</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Matteo_T/0/1/0/all/0/1">Tiziana Di Matteo</a>
We examine the early growth of supermassive black holes (SMBHs) using
constrained realization cosmological simulations. We reconstruct the initial
conditions (ICs) in the large volume BlueTides (BT) hydrodynamic simulation and
run them to $z=6$. We compare the constrained simulations with BT to test the
accuracy of this method for reproducing the first quasars and their
environments. At the high redshifts of interest, non-linear mode coupling on
the scale of even small simulation box sizes is not present. This allows our
re-simulations in a volume of $(15h^{-1}{rm Mpc})^3$ to correctly recover the
evolution of large-scale structure, and the stellar and BH mass functions in
the vicinity of a $sim10^{12}M_{odot}$ halo which we identified in BT at
$zsim7$ to be hosting a $sim10^9M_{odot}$ SMBH. Our re-simulations confirm
that only with the lowest tidal field, high-density peaks in the ICs can induce
the fastest BH growth required to explain the $z>6$ quasars. We carry out three
simulations with the same ICs but different BH seed masses of $5times10^3$,
$5times10^4$, and $5times10^5h^{-1}M_{odot}$ (the one used in BT) while
keeping the halo to BH mass ratio fixed. We find that the BH mass converges to
$sim10^9M_{odot}$ by $z=6$ regardless of the seeding procedure while their
early growth histories at $z>10$ differ. The simulations with small BH seeds
lead to the emergence of a large population of BHs which merge frequently at
early times (four BH mergers, with masses $10^4sim10^6M_{odot}$ at
$zgtrsim12$). This is also accompanied by a few major BH mergers at
$zlesssim8$ for intermediate and small BH seeds while there are no mergers in
the large BH seed simulation. The increased BH merger rate for low mass BH
seeds provides an exciting prospect for discriminating BH formation mechanisms
with the advent of multi-messenger astrophysics and next-generation GW
facilities.
We examine the early growth of supermassive black holes (SMBHs) using
constrained realization cosmological simulations. We reconstruct the initial
conditions (ICs) in the large volume BlueTides (BT) hydrodynamic simulation and
run them to $z=6$. We compare the constrained simulations with BT to test the
accuracy of this method for reproducing the first quasars and their
environments. At the high redshifts of interest, non-linear mode coupling on
the scale of even small simulation box sizes is not present. This allows our
re-simulations in a volume of $(15h^{-1}{rm Mpc})^3$ to correctly recover the
evolution of large-scale structure, and the stellar and BH mass functions in
the vicinity of a $sim10^{12}M_{odot}$ halo which we identified in BT at
$zsim7$ to be hosting a $sim10^9M_{odot}$ SMBH. Our re-simulations confirm
that only with the lowest tidal field, high-density peaks in the ICs can induce
the fastest BH growth required to explain the $z>6$ quasars. We carry out three
simulations with the same ICs but different BH seed masses of $5times10^3$,
$5times10^4$, and $5times10^5h^{-1}M_{odot}$ (the one used in BT) while
keeping the halo to BH mass ratio fixed. We find that the BH mass converges to
$sim10^9M_{odot}$ by $z=6$ regardless of the seeding procedure while their
early growth histories at $z>10$ differ. The simulations with small BH seeds
lead to the emergence of a large population of BHs which merge frequently at
early times (four BH mergers, with masses $10^4sim10^6M_{odot}$ at
$zgtrsim12$). This is also accompanied by a few major BH mergers at
$zlesssim8$ for intermediate and small BH seeds while there are no mergers in
the large BH seed simulation. The increased BH merger rate for low mass BH
seeds provides an exciting prospect for discriminating BH formation mechanisms
with the advent of multi-messenger astrophysics and next-generation GW
facilities.
http://arxiv.org/icons/sfx.gif
