1,413 research outputs found
Steady General Relativistic Magnetohydrodynamic Inflow/Outflow Solution along Large-Scale Magnetic Fields that Thread a Rotating Black Hole
General relativistic magnetohydrodynamic (GRMHD) flows along magnetic fields
threading a black hole can be divided into inflow and outflow parts, according
to the result of the competition between the black hole gravity and
magneto-centrifugal forces along the field line. Here we present the first
self-consistent, semi-analytical solution for a cold, Poynting flux-dominated
(PFD) GRMHD flow, which passes all four critical (inner and outer, Alfven and
fast magnetosonic) points along a parabolic streamline. By assuming that the
dominating (electromagnetic) component of the energy flux per flux tube is
conserved at the surface where the inflow and outflow are separated, the
outflow part of the solution can be constrained by the inflow part. The
semi-analytical method can provide fiducial and complementary solutions for
GRMHD simulations around the rotating black hole, given that the black hole
spin, global streamline, and magnetizaion (i.e., a mass loading at the
inflow/outflow separation) are prescribed. For reference, we demonstrate a
self-consistent result with the work by McKinney in a quantitative level.Comment: 13 Pages, incliding 2 tables and 5 Figures; accepted by Ap
Observable Emission Features of Black Hole GRMHD Jets on Event Horizon Scales
The general-relativistic magnetohydrodynamical (GRMHD) formulation for black
hole-powered jets naturally gives rise to a stagnation surface, wherefrom
inflows and outflows along magnetic field lines that thread the black hole
event horizon originate. We derive a conservative formulation for the transport
of energetic electrons which are initially injected at the stagnation surface
and subsequently transported along flow streamlines. With this formulation the
energy spectra evolution of the electrons along the flow in the presence of
radiative and adiabatic cooling is determined. For flows regulated by
synchrotron radiative losses and adiabatic cooling, the effective radio
emission region is found to be finite, and geometrically it is more extended
along the jet central axis. Moreover, the emission from regions adjacent to the
stagnation surface is expected to be the most luminous as this is where the
freshly injected energetic electrons concentrate. An observable stagnation
surface is thus a strong prediction of the GRMHD jet model with the prescribed
non-thermal electron injection. Future millimeter/sub-millimeter (mm/sub-mm)
very-long-baseline interferometric (VLBI) observations of supermassive black
hole candidates, such as the one at the center of M87, can verify this GRMHD
jet model and its associated non-thermal electron injection mechanism.Comment: 19 pages, 12 figure; accepted for publication in Ap
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