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We present a novel, relativistic accretion model for accretion onto aSchwarzschild black hole. This consists of a purely hydrodynamical mechanism inwhich, by breaking spherical symmetry, a radially accreting flow transitionsinto an inflow-outflow configuration. The spherical symmetry is broken byconsidering that the accreted material is more concentrated on an equatorialbelt, leaving the polar regions relatively under-dense. What we have found is aflux-limited accretion regime in which, for a sufficiently large accretionrate, the incoming material chokes at a gravitational bottleneck and the excessflux is redirected by the density gradient as a bipolar outflow. The thresholdvalue at which the accreting material chokes is of the order of the massaccretion rate found in the spherically symmetric case studied by Bondi andMichel. We describe the choked accretion mechanism first in terms of a generalrelativistic, analytic toy model based on the assumption of anultrarelativistic stiff fluid. We then relax this approximation and, by meansof numerical simulations, show that this mechanism can operate also for generalpolytropic fluids. Interestingly, the qualitative inflow-outflow morphologyobtained appears as a generic result of the proposed symmetry break, acrossanalytic and numeric results covering both the Newtonian and relativisticregimes. The qualitative change in the resulting steady state flowconfiguration appears even for a very small equatorial to polar densitycontrast ($\sim 0.1\,\%$) in the accretion profile. Finally, we discuss theapplicability of this model as a jet-launching mechanism in differentastrophysical settings.

Choked accretion onto a Schwarzschild black hole: A hydrodynamical jet-launching mechanism