Related papers: State Transitions in Black Hole Candidates
In currently favoured hierarchical cosmologies, the formation of massive black hole binaries (MBHBs) following galaxy mergers is unavoidable. Still, due the complex physics governing the (hydro)dynamics of the post-merger dense environment…
We present a set of four three-dimensional, general relativistic, radiation MHD simulations of black hole accretion at super-critical mass accretion rates, $\dot{M} > \dot{M}_{\rm Edd}$. We use these simulations to study how disk properties…
In this paper I review and discuss the basic concepts of accretion disks, focused especially on the case of accretion disks around black holes. The well known alpha-model is revisited, showing the strengths and weaknesses of the model.…
Accretion flows are fundamentally turbulent systems, yet are classically modelled with viscous theories only valid on length scales significantly greater than the typical size of turbulent eddies in the flow. We demonstrate that, while this…
Compact binaries have long been a paradigm for accretion theory. Much of our present view of how accretion occurs comes directly from the comparison of theory with observations of these sources. Since theory differs little for other objects…
It has long been suspected that black hole accretion-outflow coupling is invariant from the stellar to supermassive scales. Stellar mass black hole accretion flows are known to launch jets and outflows as they transition through critical…
We investigate the properties of accretion flows onto a black hole (BH) with a mass of $M_{\rm BH}$ embedded in an initially uniform gas cloud with a density of $n_{\infty}$ in order to study rapid growth of BHs in the early Universe. In…
Truncated accretion disks are commonly invoked to explain the spectro-temporal variability from accreting black holes in both small systems, i.e. state transitions in galactic black hole binaries (GBHBs), and large systems, i.e.…
A summary is given of the high-lights during the Reykjavik Midsummer Symposium on Non-Linear Phenomena in Accretion Discs around Black Holes. Such high-lights include the recent advances on understanding: 1) the accretion disc solution…
Although the occurrence of steady supercritical disk accretion onto a black hole has been speculated about since the 1970s, it has not been accurately verified so far. For the first time, we previously demonstrated it through…
The brane-world description of our universe entails a large extra dimension and a fundamental scale of gravity that might be lower by several orders of magnitude compared to the Planck scale. An interesting consequence of the brane-world…
We present a detailed temporal analysis of a set of hydrodynamic and magnetohydrodynamic (MHD) simulations of geometrically-thin (h/r~0.05) black hole accretion disks. The black hole potential is approximated by the Paczynski-Wiita…
Aims: The hard and soft spectral states of black hole accretion are understood as connected with ADAF accretion (truncated disk) and standard disk accretion, respectively. However, observations indicate the existence of cool gas in the…
Following a tidal disruption event (TDE), the accretion rate can evolve from quiescent to near-Eddington levels and back over months - years timescales. This provides a unique opportunity to study the formation and evolution of the…
Supermassive black holes (BH) accrete gas from their surroundings and coalesce with companions during galaxy mergers, and both processes change the BH mass and spin. By means of high-resolution hydrodynamical simulations of galaxies, either…
We present results of several numerical simulations of two dimensional axi-symmetric accretion flows around black holes using the Smoothed Particle Hydrodynamics (SPH). We consider both stellar black holes and as well as super-massive black…
Context: Accretion onto galactic and supermassive black holes occurs in different modes, which are documented in hard and soft spectral states, commonly attributed to an advection-dominated flow (ADAF) inside a truncated disk and standard…
Accretion onto supermassive black holes (SMBHs) in realistic halos is time-variable, governed by turbulence, cooling, and multiphase condensation. In chaotic cold accretion (CCA), clouds and filaments condense out of the hot gas and feed…
We study the thermal and viscous stability of accretion flows in Low Mass Black Hole Binaries (LMBHBs). We consider a model in which an inner advection-dominated accretion flow (ADAF) is surrounded by a geometrically thin accretion disk,…
We present time-dependent simulations of a two-phase accretion flow around a black hole. The accretion flow initially is composed of an optically thick and cool disc close to the midplane, while on top and below the disc there is a hot and…