The radiative efficiency of super-Eddington accreting black holes ( BHs ) is explored for magnetically-arrested disks ( MADs ) , where magnetic flux builds-up to saturation near the BH .
Our three-dimensional general relativistic radiation magnetohydrodynamic ( GRRMHD ) simulation of a spinning BH ( spin a / M = 0.8 ) accreting at \sim 50 times Eddington shows a total efficiency \sim 50 \% when time-averaged and total efficiency \gtrsim 100 \% in moments .
Magnetic compression by the magnetic flux near the rotating BH leads to a thin disk , whose radiation escapes via advection by a magnetized wind and via transport through a low-density channel created by a Blandford-Znajek ( BZ ) jet .
The BZ efficiency is sub-optimal due to inertial loading of field lines by optically thick radiation , leading to BZ efficiency \sim 40 \% on the horizon and BZ efficiency \sim 5 \% by r \sim 400 r _ { g } ( gravitational radii ) via absorption by the wind .
Importantly , radiation escapes at r \sim 400 r _ { g } with efficiency \eta \approx 15 \% ( luminosity L \sim 50 L _ { Edd } ) , similar to \eta \approx 12 \% for a Novikov-Thorne thin disk and beyond \eta \lesssim 1 \% seen in prior GRRMHD simulations or slim disk theory .
Our simulations show how BH spin , magnetic field , and jet mass-loading affect the radiative and jet efficiencies of super-Eddington accretion .