The origins and impact of outflow from super-Eddington flow

It is widely believed that super-Eddington accretion flow can produce powerful outflow, but where does this originate and how much mass and energy are carried away in which directions? To answer these questions, we perform a new large-box, two-dimensional radiation hydrodynamic simulation, paying special attention lest the results should depend on the adopted initial and boundary conditions. We achieve a quasi-steady state at an unprecedentedly large range, r = 2-600r(S) (with r(S) being the Schwarzschild radius), from the black hole. The accretion rate onto the central 10M(circle dot) black hole is (M)over dot(BH) similar to 180L(Edd)/c(2), whereas the mass outflow rate is (M)over dot(outflow) similar to 24L(Edd)/c(2) (where L-Edd and c are the Eddington luminosity and the speed of light, respectively). The ratio (M)over dot(outflow)/(M)over dot(BH) similar to 0.14 is much less than previously reported. By careful inspection we find that most of the outflowing gas reaching the outer boundary originates from the region at R less than or similar to 140r(S), while gas at 140-230r(S) forms failed outflow. Therefore, significant outflow occurs inside the trapping radius similar to 450r(S). The mechanical energy flux (or mass flux) reaches its maximum in the direction of similar to 15 degrees (similar to 80 degrees) from the rotation axis. The total mechanical luminosity is L-mec similar to 0.16L(Edd), while the isotropic X-ray luminosity varies from L-X(ISO) similar to 2.9L(Edd) (for a face-on observer) to similar to 2.1L(Edd) (for a nearly edge-on observer). The power ratio is L-mec/L-X(ISO) similar to 0.05-0.08, in good agreement with observations of ultraluminous X-ray sources surrounded by optical nebulae.

Automated summary

Research through simulation found that most of the mass and energy outflow generated by super-Eddington accretion flow originates near the black hole, with the majority of the outflowing gas forming inside the trapping radius. The mechanical energy flux reaches its maximum in the direction of 15 degrees from the rotation axis.