We describe three-dimensional general relativistic magnetohydrodynamic simulations of a geometrically thin accretion disk around a non-spinning black hole. The disk has a thickness h/r ∼ 0.05−0.1 over the radius range (2−20)GM/c2. In steady state, the specific angular momentum profile of the inflowing magnetized gas deviates by less than 2% from that of the standard thin disk model of Novikov &...

We have carried out 2D and 3D general relativistic magnetohydrodynamic simulations of jets launched self-consistently from accretion disks orbiting Kerr black holes and applied the results to the inner engine of the collapsar model of gamma-ray bursts. The accretion flow launches energetic jets in the axial funnel region of the disk/jet system, as well as a substantial coronal wind. The jets fe...

Special and general relativistic effects on the X-ray emissions, especially the continuum spectra, from the accretion disks around black holes are investigated using the ray-tracing method. Because both the special and general relativistic effects are more important at distances closer to the black hole, the relativistic modifications to the emitted X-ray spectra are more significant at higher ...

We present a systematic numerical study of two-dimensional axisymmetric accretion flows around black holes. The flows have no radiative cooling and are treated in the framework of the hydrodynamical approximation. The models calculated in this study cover the large range of the relevant parameter space. There are four types of flows, determined by the values of the viscosity parameter α and the...

We consider the radial structure of radiatively inefficient hydrodynamic accretion flows around black holes. We show that low-viscosity flows consist of two zones: an outer convection-dominated zone and an inner advection-dominated zone. The transition between these two zones occurs at ∼ 50 Schwarzschild radii. Subject headings: accretion, accretion disks — black hole physics — convection Depar...

Qualitative arguments are presented to demonstrate that the energy density of magnetic fields in matter accreting onto a black hole inside the marginally stable orbit is automatically comparable to the rest-mass energy density of the accretion flow. Several consequences follow: magnetic effects must be dynamically significant, but cannot be so strong as to dominate; outward energy transport in ...

We calculate the spectra of two-component accretion flows around black holes of various masses, from quasars to nano-quasars. Specifically, we fit the observational data of M87 very satisfactorily using our model and find that the spectrum may be well fitted by a sub-Keplerian component alone, and there is little need of any Keplerian component. The non-thermal distribution of electrons produce...

We provide a schematic framework for understanding observations of jet suppression in soft state black hole X-ray binaries based on the Blandford-Payne process and the net magnetic flux threading the black hole. Due to the geometrical thinness of soft state disks, mass-loading of field lines is ineffective compared to both geometrically thick disks as well as thin disks with greater black hole ...

The faintest ultraluminous X-ray sources (ULXs), those with 0.3–10 keV luminosities 1 < LX/10 39 < 3 erg s, tend to have X-ray spectra that are disk-like but broader than expected for thin accretion disks. These ‘broadened disk’ spectra are thought to indicate nearor mildly super-Eddington accretion onto stellar remnant black holes. Here we report that a sample of bright thermal-dominant black ...