Shock oscillation model for quasi-periodic oscillations in stellar mass and supermassive black holes

Abstract

We numerically examine centrifugally supported shock waves in 2D rotating accretion flows around a stellar mass (10 M⊙) and a supermassive (10 6 M⊙) black holes over a wide range of input accretion rates of 10 7 ≥) M/ME≥ 10 -4 . The resultant 2D shocks are unstable with time and the luminosities show quasi-periodic oscillations (QPOs) with modulations of a factor of 2-3 and with periods of a tenth of a second to several hours, depending on the black hole masses. The shock oscillation model may explain the intermediate frequency QPOs with 1-10 Hz observed in the stellar mass black hole candidates and also suggest the existence of QPOs with the period of hours in active galactic nuclei. When the accretion rate M is low, the luminosity increases in proportion to the accretion rate. However, when M greatly exceeds the Eddington critical rate M E , the luminosity is insensitive to the accretion rate and is kept constantly around ∼3L E· On the other hand, the mass-outflow rate M loss increases in proportion to M and it amounts to about a few per cent of the input mass-flow rate.