A Radiation-Hydrodynamical Model for Supermassive Black Hole-to-Bulge Mass Relation and Quasar Formation

As a potential mechanism to build up supermassive black holes (BHs) in a spheroidal system, we consider the radiation drag effect by bulge stars, which extracts angular momentum from interstellar gas and thus allows the gas to accrete onto the galactic center. By incorporating the radiation hydrodynamical equation with simple stellar evolution, it is shown that the BH-to-bulge mass ratio, f_BH, is basically determined by a fundamental constant, that is, the energy conversion efficiency for nuclear fusion of hydrogen to helium, ɛ=0.007. More specifically, f_BH is predicted to be 0.3ɛ-0.5ɛ. Based on the present model for BH growth, a scenario for quasar formation is addressed in relation to ultraluminous infrared galaxies.