Evidence on the Origin of Ergospheric Disk Field Line Topology in
  Simulations of Black Hole Accretion
  This Letter investigates the origin of the asymmetric magnetic field line
geometry in the ergospheric disk (and the corresponding asymmetric powerful
jet) in 3-D perfect magnetohydrodynamic (MHD) numerical simulations of a
rapidly rotating black hole accretion system reported in \citet{pun10}.
Understanding, why and how these unexpected asymmetric structures form is of
practical interest because an ergospheric disk jet can boost the black hole
driven jet power many-fold possibly resolving a fundamental disconnect between
the energy flux estimates of powerful quasar jets and simulated jet power
\citep{pun11}. The new 3-D simulations of \citet{bec09} that were run with
basically the same code that was used in the simulation discussed in
\citet{pun10} describe the "coronal mechanism" of accreting poliodal magnetic
flux towards the event horizon. It was determined that reconnection in the
inner accretion disk is a "necessary" component for this process. The coronal
mechanism seems to naturally explain the asymmetric ergospheric disk field
lines that were seen in the simulations. Using examples from the literature, it
is discussed how apparently small changes in the reconnection geometry and
rates can make enormous changes in the magnetospheric flux distribution and the
resultant black hole driven jet power in a numerical simulation. Unfortunately,
reconnection is a consequence of numerical diffusion and not a detailed (yet to
be fully understood) physical mechanism in the existing suite of perfect MHD
based numerical simulations. The implication is that there is presently great
uncertainty in the flux distribution of astrophysical black hole magnetospheres
and the resultant jet power.
