Choked accretion onto a Schwarzschild black hole: A hydrodynamical jet-launching mechanism. (arXiv:1909.01527v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Tejeda_E/0/1/0/all/0/1">Emilio Tejeda</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Aguayo_Ortiz_A/0/1/0/all/0/1">Alejandro Aguayo-Ortiz</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hernandez_X/0/1/0/all/0/1">X. Hernandez</a>
We present a novel, relativistic accretion model onto a Schwarzschild black
hole. This consists of a purely hydrodynamical mechanism in which, by breaking
spherical symmetry, a radially accreting flow transitions into an
inflow-outflow configuration. The spherical symmetry is broken by considering
that the accreted material is more concentrated on an equatorial belt, leaving
the polar regions relatively under-dense. What we have found is a flux-limited
accretion regime in which, for a sufficiently large accretion rate, the
incoming material chokes at a gravitational bottleneck and the excess flux is
redirected by the density gradient as a bipolar outflow. The threshold value at
which the accreting material chokes is of the order of the mass accretion rate
found in the spherically symmetric case studied by Bondi and Michel. We
describe the choked accretion mechanism first in terms of a general
relativistic, analytic toy model based on the assumption of an
ultrarelativistic stiff fluid. We then relax this approximation and, by means
of numerical simulations show that this mechanism can operate also for general
polytropic fluids. Interestingly, the qualitative inflow-outflow morphology
obtained appears as a generic result of the proposed symmetry break, across
analytic and numeric results covering both the Newtonian and relativistic
regimes. Finally, we discuss the applicability of this model as a jet-launching
mechanism in different astrophysical settings.
We present a novel, relativistic accretion model onto a Schwarzschild black
hole. This consists of a purely hydrodynamical mechanism in which, by breaking
spherical symmetry, a radially accreting flow transitions into an
inflow-outflow configuration. The spherical symmetry is broken by considering
that the accreted material is more concentrated on an equatorial belt, leaving
the polar regions relatively under-dense. What we have found is a flux-limited
accretion regime in which, for a sufficiently large accretion rate, the
incoming material chokes at a gravitational bottleneck and the excess flux is
redirected by the density gradient as a bipolar outflow. The threshold value at
which the accreting material chokes is of the order of the mass accretion rate
found in the spherically symmetric case studied by Bondi and Michel. We
describe the choked accretion mechanism first in terms of a general
relativistic, analytic toy model based on the assumption of an
ultrarelativistic stiff fluid. We then relax this approximation and, by means
of numerical simulations show that this mechanism can operate also for general
polytropic fluids. Interestingly, the qualitative inflow-outflow morphology
obtained appears as a generic result of the proposed symmetry break, across
analytic and numeric results covering both the Newtonian and relativistic
regimes. Finally, we discuss the applicability of this model as a jet-launching
mechanism in different astrophysical settings.
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