APO3 - The Origins of Massive Black Holes and Quasars at High Redshifts |
Speaker_ |
Okuda, Toru |
Co-autors |
V. Teresi, D.Molteni |
Talk _ |
QPOs due to Centrifugally Supported Shocks around Stellar-Mass and Supermassive Black Holes |
Abstract _ |
We examine centrifugally supported shocks formed in low-angular momentum accretion flows around stellar-mass and supermassive black holes, by 2D-hydrodynamical calculations, while taking account of the cooling and heating of the gas and the radiation transport. With a set of adequate injection parameters, shock waves appear at 5-20 Schwartzschild radii. However, the radiative shocks are unstable with time and oscillate quasi-periodically around the above shock position. The resultant luminosities behave as the quasi-periodic oscillations (QPOs) with modulations of a factor 3 and with quasi-periods of a tenth seconds to several hours, depending on the black hole masses. These shock-oscillation models may not only explain the intermediate frequency QPO with 1–10 Hz observed in the black hole candidate GRS 1915+105 but also suggest the existence of QPOs with the period of hours in AGNs. |