In this Letter, we suggest that the relativistic protons powering the outflows emanating from radio-loud systems containing black holes are accelerated at standing, centrifugally supported shocks in hot advection-dominated accretion disks. Such disks are ideal sites for first-order Fermi acceleration at shocks because the gas is tenuous, and consequently the mean free path for particle-particle...

We have carried out 2D and 3D general relativistic magnetohydrodynamic simulations of jets launched self-consistently from accretion disks orbiting Kerr black holes. The accretion flow generates energetic jets in the axial funnel region of the disk/jet system, as well as a substantial coronal wind. The jets feature knot-like structures of extremely hot, ultra-relativistic gas; the gas in these ...

We study the evolution of disk accretion during the merger of supermassive black hole binaries in galactic nuclei. In hierarchical galaxy formation models, the most common binaries are likely to arise from minor galactic mergers, and have unequal mass black holes. Once such a binary becomes embedded in an accretion disk at a separation a ∼ 0.1 pc, the merger proceeds in two distinct phases. Dur...

We present the first results from two-dimensional simulations of radiatively-efficient accretion of metal-free gas onto intermediate-mass black holes. We fix the shape of the spectral energy distribution of the radiation produced near the event horizon and study the structure of the irradiated low-angular-momentum accretion flow over three orders of magnitude in radius from the black hole, 1014...

I consider models of active galactic nuclei, stellar-mass accreting black holes and microquasars based on a previously developed (Katz (1997)) model of gamma-ray bursts. When energy fluxes exceed a critical value ∼ 10 erg/cms, as in GRB, a black-body equilibrium pair plasma forms. At the lower fluxes found in AGN, BHXS and microquasars accretion power electrodynamically accelerates a small numb...

We present a novel method to measure the accretion rate of radio emitting X-ray binaries (XRBs) and active galactic nuclei (AGN) independently of the X-ray luminosity. The radio emission of the jet is used as a tracer for the accretion rate and is normalised using sources of known accretion rates: island state neutron stars and efficiently radiating black holes close to a state transition. We s...

Recent X-ray observations of microquasars and Seyfert galaxies reveal the broad emission lines in their spectra, which can arise in the innermost parts of accretion disks. Simulation indicates that at low inclination angle the line is registered by distant observer with characteristic two-peak profile. However, at high inclination angles (> 85 •) two additional peaks arise. This phenomenon was ...

Accretion disks around supermassive black holes have regions where the Rosseland mean opacity can be larger than the electron scattering opacity due to the large number of bound–bound transitions in iron. We study the effects of this iron opacity “bump” on the thermal stability and vertical structure of radiation-pressure-dominated accretion disks, utilizing three-dimensional radiation magnetoh...

The existence of hot, two-temperature accretion flows is essential to the recent discussions of the low luminosity, hard X-ray emission from accreting neutron stars and black holes in Galactic binaries and massive black holes in low luminosity galactic nuclei. In these flows, protons are essentially virialized and relativistic energies for non-thermal protons are likely. Observational confirmat...