Three-Dimensional General Relativistic Radiation Magnetohydrodynamical
  Simulation of Super-Eddington Accretion, using a new code HARMRAD with M1
  Closure
  Black hole (BH) accretion flows and jets are dynamic hot relativistic
magnetized plasma flows whose radiative opacity can significantly affect flow
structure and behavior. We describe a numerical scheme, tests, and an
astrophysically relevant application using the M1 radiation closure within a
new three-dimensional (3D) general relativistic (GR) radiation (R)
magnetohydrodynamics (MHD) massively parallel code called HARMRAD. Our 3D
GRRMHD simulation of super-Eddington accretion (about $20$ times Eddington)
onto a rapidly rotating BH (dimensionless spin $j=0.9375$) shows sustained
non-axisymmemtric disk turbulence, a persistent electromagnetic jet driven by
the Blandford-Znajek effect, and a total radiative output consistently near the
Eddington rate. The total accretion efficiency is of order $20\%$, the
large-scale electromagnetic jet efficiency is of order $10\%$, and the total
radiative efficiency that reaches large distances remains low at only order
$1\%$. However, the radiation jet and the electromagnetic jet both emerge from
a geometrically beamed polar region, with super-Eddington isotropic equivalent
luminosities. Such simulations with HARMRAD can enlighten the role of BH spin
vs.\ disks in launching jets, help determine the origin of spectral and
temporal states in x-ray binaries, help understand how tidal disruption events
(TDEs) work, provide an accurate horizon-scale flow structure for M87 and other
active galactic nuclei (AGN), and isolate whether AGN feedback is driven by
radiation or by an electromagnetic, thermal, or kinetic wind/jet. For example,
the low radiative efficiency and weak BH spin-down rate from our simulation
suggest that BH growth over cosmological times to billions of solar masses by
redshifts of $z\sim 6-8$ is achievable even with rapidly rotating BHs and ten
solar mass BH seeds.
