We perform one-dimensional radiation hydrodynamical simulations to solve accretion flows onto massive black holes ( BHs ) with a very high rate .
Assuming that photon trapping limits the luminosity emerging from the central region to L \la L _ { Edd } , Inayoshi , Haiman & Ostriker ( 2016 ) have shown that an accretion flow settles to a “ hyper-Eddington ” solution , with a steady and isothermal ( T \simeq 8000 K ) Bondi profile reaching \ga 5000 times the Eddington accretion rate \dot { M } _ { Edd } \equiv L _ { Edd } / c ^ { 2 } .
Here we address the possibility that gas accreting with finite angular momentum forms a bright nuclear accretion disc , with a luminosity exceeding the Eddington limit ( 1 \la L / L _ { Edd } \la 100 ) .
Combining our simulations with an analytic model , we find that a transition to steady hyper-Eddington accretion still occurs , as long as the luminosity remains below L / L _ { Edd } \lesssim 35 ~ { } ( M _ { BH } / 10 ^ { 4 } ~ { } M _ { \odot } ) ^ { 3 / 2 } ( n _ { \infty } / 10 % ^ { 5 } ~ { } { cm ^ { -3 } } ) ( T _ { \infty } / 10 ^ { 4 } ~ { } { K } ) ^ { -3 / 2 } ( r _ { \star } / 10 ^ { 14 } ~ { } % { cm } ) ^ { -1 / 2 } , where n _ { \infty } and T _ { \infty } are the density and temperature of the ambient gas , and r _ { \star } is the radius of the photosphere , at which radiation emerges .
If the luminosity exceeds this value , accretion becomes episodic .
Our results can be accurately recovered in a toy model of an optically thick spherical shell , driven by radiation force into a collapsing medium .
When the central source is dimmer than the above critical value , the expansion of the shell is halted and reversed by ram pressure of the collapsing medium , and by shell ’ s weight .
Our results imply that rapid , unimpeded hyper-Eddington accretion is possible even if the luminosity of the central source far exceeds the Eddington limit , and can be either steady or strongly episodic .