Numerical simulations of super-critical black hole accretion flows in general relativity

Sądowski, Aleksander; Narayan, Ramesh; McKinney, Jonathan C.; Tchekhovskoy, Alexander

doi:10.1093/mnras/stt2479

Cited by 286 publications

(361 citation statements)

References 74 publications

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“…This prescription is motivated by the simulations withṁ 1, mentioned above, which find that photon trapping do not fully suppress the luminosity emerging from the central region (e.g., Jiang, Stone & Davis 2014;Sadowski et al 2014). We set spherical coordinates with a logarithmicallyspaced grid in the radial direction as follows.…”

Section: Basic Equations and Numerical Schemesmentioning

confidence: 99%

Hyper-Eddington mass accretion on to a black hole with super-Eddington luminosity

Sakurai

Inayoshi

Haiman

2016

Mon. Not. R. Astron. Soc.

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We perform one-dimensional radiation hydrodynamical simulations to solve accretion flows onto massive black holes (BHs) with a very high rate. Assuming that photon trapping limits the luminosity emerging from the central region to L L Edd , Inayoshi, Haiman & Ostriker (2016) have shown that an accretion flow settles to a "hyper-Eddington" solution, with a steady and isothermal (T 8000 K) Bondi profile reaching 5000 times the Eddington accretion rateṀ Edd ≡ L Edd /c 2 . Here we address the possibility that gas accreting with finite angular momentum forms a bright nuclear accretion disc, with a luminosity exceeding the Eddington limit (1 L/L Edd 100). Combining our simulations with an analytic model, we find that a transition to steady hyper-Eddington accretion still occurs, as long as the luminosity remains below L/L Edd 35 (M BH /10 4 M ) 3/2 (n ∞ /10 5 cm −3 )(T ∞ /10 4 K) −3/2 (r /10 14 cm) −1/2 , where n ∞ and T ∞ are the density and temperature of the ambient gas, and r is the radius of the photosphere, at which radiation emerges. If the luminosity exceeds this value, accretion becomes episodic. Our results can be accurately recovered in a toy model of an optically thick spherical shell, driven by radiation force into a collapsing medium. When the central source is dimmer than the above critical value, the expansion of the shell is halted and reversed by ram pressure of the collapsing medium, and by shell's weight. Our results imply that rapid, unimpeded hyper-Eddington accretion is possible even if the luminosity of the central source far exceeds the Eddington limit, and can be either steady or strongly episodic.

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Section: Basic Equations and Numerical Schemesmentioning

confidence: 99%

Hyper-Eddington mass accretion on to a black hole with super-Eddington luminosity

Sakurai

Inayoshi

Haiman

2016

Mon. Not. R. Astron. Soc.

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“…The magnetic field is not only able to provide the stress we need to transfer angular momentum, but also generates an additional cooling mechanism (Turner 2004;Hirose et al 2009aHirose et al , 2009bBlaes et al 2011;Jiang et al 2013a) and coronae above the disk (Jiang et al 2014b). Structures of accretion disks in the super-Eddington regime have also been studied with global two (2D) as well three-dimensional (3D) magneto-hydrodynamic (MHD) simulations, where radiative transfer equation is solved with flux-limited diffusion (FLD) or M1 closure (Ohsuga & Mineshige 2011;McKinney et al 2014;Sadowski et al 2014). These global simulations confirm many properties of the slim disk model.…”

Section: Introductionmentioning

confidence: 99%

A Global Three-Dimensional Radiation Magneto-Hydrodynamic Simulation of Super-Eddington Accretion Disks

Jiang

Stone

Davis

2014

ApJ

387

473

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We study super-Eddington accretion flows onto black holes using a global three-dimensional radiation magneto-hydrodynamical simulation. We solve the time-dependent radiative transfer equation for the specific intensities to accurately calculate the angular distribution of the emitted radiation. Turbulence generated by the magneto-rotational instability provides self-consistent angular momentum transfer. The simulation reaches inflow equilibrium with an accretion rate ∼220 L Edd /c 2 and forms a radiation-driven outflow along the rotation axis. The mechanical energy flux carried by the outflow is ∼20% of the radiative energy flux. The total mass flux lost in the outflow is about 29% of the net accretion rate. The radiative luminosity of this flow is ∼10 L Edd . This yields a radiative efficiency ∼4.5%, which is comparable to the value in a standard thin disk model. In our simulation, vertical advection of radiation caused by magnetic buoyancy transports energy faster than photon diffusion, allowing a significant fraction of the photons to escape from the surface of the disk before being advected into the black hole. We contrast our results with the lower radiative efficiencies inferred in most models, such as the slim disk model, which neglect vertical advection. Our inferred radiative efficiencies also exceed published results from previous global numerical simulations, which did not attribute a significant role to vertical advection. We briefly discuss the implications for the growth of supermassive black holes in the early universe and describe how these results provided a basis for explaining the spectrum and population statistics of ultraluminous X-ray sources.

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“…The overall behaviour of the net angular momentum in the simulations by Shafee et al (2008) conforms well with the conventional picture of hydrodynamic transonic accretion: nearly Keplerian rotation outside the last stable orbit, Keplerian rotation at the sonic surface and roughly constant angular momentum (uϕ) in the supersonic region. On the other hand, Sadowski et al (2014) find the net angular momentum rapidly decreasing inside the last stable orbit.…”

Section: Numerical Simulationsmentioning

confidence: 91%

“…In simulations B1h and D1, we assumed the initial magnetic field potential scaling with the rest-mass density as Aϕ ∝ ρ. However, in Sadowski et al (2014), the magnetic field obeys a different, more complicated law making it stronger further from the black hole. This leads to a gradual increase in magnetization of the accreting matter even during quasi-stationary accretion (see also Fig.…”

Section: Numerical Simulationsmentioning

confidence: 99%

See 1 more Smart Citation

On the Eddington limit for relativistic accretion discs

Abolmasov¹,

Chashkina²

2015

Mon. Not. R. Astron. Soc.

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Standard accretion disc model relies upon several assumptions, the most important of which is geometrical thinness. Whenever this condition is violated, new physical effects become important such as radial energy advection and mass loss from the disc. These effects are important, for instance, for large mass accretion rates when the disc approaches its local Eddington limit. In this work, we study the upper limits for standard accretion disc approximation and find the corrections to the standard model that should be considered in any model aiming on reproducing the transition to super-Eddington accretion regime. First, we find that for thin accretion disc, taking into account relativistic corrections allows to increase the local Eddington limit by about a factor of two due to stronger gravity in General Relativity (GR). However, violation of the local Eddington limit also means large disc thickness. To consider consequently the disc thickness effects, one should make assumptions upon the twodimensional rotation law of the disc. For rotation frequency constant on cylinders r sin θ = const, vertical gravity becomes stronger with height on spheres of constant radius. On the other hand, effects of radial flux advection increase the flux density in the inner parts of the disc and lower the Eddington limit. In general, the effects connected to disc thickness tend to increase the local Eddington limit even more. The efficiency of accretion is however decreased by advection effects by about a factor of several.

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Numerical simulations of super-critical black hole accretion flows in general relativity

Cited by 286 publications

References 74 publications

Hyper-Eddington mass accretion on to a black hole with super-Eddington luminosity

Hyper-Eddington mass accretion on to a black hole with super-Eddington luminosity

A Global Three-Dimensional Radiation Magneto-Hydrodynamic Simulation of Super-Eddington Accretion Disks

On the Eddington limit for relativistic accretion discs

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