Super-Eddington Black-Hole Models for SS 433

Okuda, Tôru

doi:10.1093/pasj/54.2.253

Cited by 51 publications

(51 citation statements)

References 49 publications

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“…Owing to their apparent complexity, the equations of radiation hydrodynamics, when applied to supercritically accreting compact objects and their surroundings, are often solved numerically (Eggum et al 1988;Okuda 2002;Okuda et al 2005;Ohsuga et al 2005;Ohsuga 2007). Simulations of such systems have also been extended to include magnetic fields (radiation magnetohydrodynamic; RMHD), the presence of which is potentially important not only for the dynamics of the gas but also for MRI-induced accretion and jet collimation (Turner et al 2003;Ohsuga et al 2009;Sądowski et al 2014;McKinney et al 2014).…”

Section: Discussionmentioning

confidence: 99%

The General Relativistic Equations of Radiation Hydrodynamics in the Viscous Limit

Coughlin

Begelman

2014

ApJ

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We present an analysis of the general relativistic Boltzmann equation for radiation, appropriate to the case where particles and photons interact through Thomson scattering, and derive the radiation energy-momentum tensor in the diffusion limit, with viscous terms included. Contrary to relativistic generalizations of the viscous stress tensor that appear in the literature, we find that the stress tensor should contain a correction to the comoving energy density proportional to the divergence of the fourvelocity, as well as a finite bulk viscosity. These modifications are consistent with the framework of radiation hydrodynamics in the limit of large optical depth, and do not depend on thermodynamic arguments such as the assignment of a temperature to the zeroth-order photon distribution. We perform a perturbation analysis on our equations and demonstrate that, as long as the wave numbers do not probe scales smaller than the mean free path of the radiation, the viscosity contributes only decaying, i.e., stable, corrections to the dispersion relations. The astrophysical applications of our equations, including jets launched from super-Eddington tidal disruption events and those from collapsars, are discussed and will be considered further in future papers.

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Section: Discussionmentioning

confidence: 99%

The General Relativistic Equations of Radiation Hydrodynamics in the Viscous Limit

Coughlin

Begelman

2014

ApJ

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“…These are the first simulations of supercritical accretion flow in the quasi-steady state. Although the research history of such simulations stems back to the late 1980s, when Eggum et al (1987) performed numerical simulations for the first time, their calculations were restricted to the first few seconds (see also Kley 1989;Okuda et al 1997;Kley & Lin 1999;Okuda 2002). Back-reactions were not fully taken into account in their simulations.…”

Section: Overview Of the Simulated Flowmentioning

confidence: 99%

Why Is Supercritical Disk Accretion Feasible?

Ohsuga

Mineshige

2007

ApJ

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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 twodimensional, long-term radiation-hydrodynamic simulations. To clarify why this accretion is possible, we quantitatively investigate the dynamics of a simulated supercritical accretion flow with a mass accretion rate of $10 2 L E /c 2 (with L E and c being, respectively, the Eddington luminosity and the speed of light). We confirm two important mechanisms underlying supercritical disk accretion flow, as previously claimed, one of which is the radiation anisotropy arising from the anisotropic density distribution of very optically thick material. We qualitatively show that despite a very large radiation energy density, E 0 k 10 2 L E /4r 2 c (with r being the distance from the black hole), the radiative flux F 0 $ cE 0 / could be small due to a large optical depth, typically $ 10 3 , in the disk. Another mechanism is photon trapping, quantified by vE 0 , where v is the flow velocity. With a large jvj and E 0 , this term significantly reduces the radiative flux and even makes it negative (inward) at r < 70r S , where r S is the Schwarzschild radius. Due to the combination of these effects, the radiative force in the direction along the disk plane is largely attenuated so that the gravitational force barely exceeds the sum of the radiative force and the centrifugal force. As a result, matter can slowly fall onto the central black hole mainly along the disk plane with velocity much less than the free-fall velocity, even though the disk luminosity exceeds the Eddington luminosity. Along the disk rotation axis, in contrast, the strong radiative force drives strong gas outflows.

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“…The dynamics of supercritical accretion flows have been studied by radiation hydrodynamic simulations (Eggum et al 1988;Okuda 2002;Ohsuga et al 2005;Ohsuga 2006) and radiation magnetohydrodynamic (MHD) simulations (Ohsuga & Mineshige 2011;Ohsuga et al 2009). Kawashima et al (2009) performed axisymmetric two-dimensional radiation hydrodynamic simulations of supercritical black hole accretion flows incorporating the Compton cooling/heating.…”

Section: Introductionmentioning

confidence: 99%

Comptonized Photon Spectra of Supercritical Black Hole Accretion Flows With Application to Ultraluminous X-Ray Sources

Kawashima

Ohsuga

Mineshige

et al. 2012

ApJ

118

140

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Radiation spectra of supercritical black hole accretion flows are computed using a Monte Carlo method by postprocessing the results of axisymmetric radiation hydrodynamic simulations. We take into account thermal/bulk Comptonization, free-free absorption, and photon trapping. We found that a shock-heated region (∼10 8 K) appears at the funnel wall near the black hole where the supersonic inflow is reflected by the centrifugal barrier of the potential. Both thermal and bulk Comptonization significantly harden photon spectra although most of the photons upscattered above 40 keV are swallowed by the black hole due to the photon trapping. When the accretion rate onto the black hole isṀ2 , where L E is the Eddington luminosity, the spectrum has a power-law component which extends up to ∼10 keV by upscattering of photons in the shock-heated region. In higher mass accretion rates, the spectra roll over around 5 keV due to downscattering of the photons by cool electrons in the dense outflow surrounding the jet. Our results are consistent with the spectral features of ultraluminous X-ray sources, which typically show either a hard power-law component extending up to 10 keV or a rollover around 5 keV. We found that the spectrum of NGC 1313 X-2 is quite similar to the spectrum numerically obtained for high accretion rate2 ) source observed with low viewing angle (i = 10Our numerical results also demonstrate that the face-on luminosity of supercritically accreting stellar mass black holes (10 M ) can significantly exceed 10 40 erg s −1 .

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Super-Eddington Black-Hole Models for SS 433

Cited by 51 publications

References 49 publications

The General Relativistic Equations of Radiation Hydrodynamics in the Viscous Limit

The General Relativistic Equations of Radiation Hydrodynamics in the Viscous Limit

Why Is Supercritical Disk Accretion Feasible?

Comptonized Photon Spectra of Supercritical Black Hole Accretion Flows With Application to Ultraluminous X-Ray Sources

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