Steady General Relativistic Magnetohydrodynamic Inflow/Outflow Solution Along Large-Scale Magnetic Fields That Thread a Rotating Black Hole

Pu, Hung-Yi; Nakamura, Masanori; Hirotani, Kouichi; Mizuno, Yosuke; Wu, Kinwah; Asada, Keiichi

doi:10.1088/0004-637x/801/1/56

Cited by 42 publications

(67 citation statements)

References 52 publications

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“…All of the codes cited above work in the ideal MHD regime (thus neglecting resistivity or magnetic diffusivity). Steady-state GR-MHD accretion-outflow solutions were presented by Pu et al (2015).…”

Section: Introductionmentioning

confidence: 99%

rHARM: ACCRETION AND EJECTION IN RESISTIVE GR-MHD

Qian

Fendt

Noble

et al. 2016

ApJ

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Turbulent magnetic diffusivity plays an important role for accretion disks and the launching of disk winds. We have implemented magnetic diffusivity, respective resistivity in the general relativistic MHD code HARM. This paper describes the theoretical background of our implementation, its numerical realization, our numerical tests and preliminary applications. The test simulations of the new code rHARM are compared with an analytic solution of the diffusion equation and a classical shock tube problem. We have further investigated the evolution of the magneto-rotational instability (MRI) in tori around black holes for a range of magnetic diffusivities. We find indication for a critical magnetic diffusivity (for our setup) beyond which no MRI develops in the linear regime and for which accretion of torus material to the black hole is delayed. Preliminary simulations of magnetically diffusive thin accretion disks around Schwarzschild black holes that are threaded by a large-scale poloidal magnetic field show the launching of disk winds with mass fluxes of about 50% of the accretion rate. The disk magnetic diffusivity allows for efficient disk accretion that replenishes the mass reservoir of the inner disk area and thus allows for long-term simulations of wind launching for more than 5000 time units.

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Section: Introductionmentioning

confidence: 99%

rHARM: ACCRETION AND EJECTION IN RESISTIVE GR-MHD

Qian

Fendt

Noble

et al. 2016

ApJ

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“…To investigate the energy variation of non-thermal electrons within a background GRMHD flow, we proceed to construct a "qualitatively correct" GRMHD flow configuration as illustrated in Figure 2 (see also McKinney 2006;Pu et al 2015).…”

Section: Flow In An Axisymmetric and Stationary Grmhd Jetmentioning

confidence: 99%

“…A global magnetic field and MHD out-flow solution is related to the mass loading onto the field lines (Beskin et al 1998;Beskin & Nokhrina 2006;Globus & Levinson 2013;Pu et al 2015) and is computationally expensive to calculate. For a description mimicking the outflow properties, we instead employ the following working assumptions.…”

Section: Flow In An Axisymmetric and Stationary Grmhd Jetmentioning

confidence: 99%

“…the relativistic Bernoulli equation in the cold limit. As shown in Pu et al (2015), a magnetically-dominated GRMHD inflow solution is insensitive to mass loading, because its Alfvén surface and fast surface are constrained to be close to the inner light surface and the event horizon, respectively. Based on such characteristic features, we have the freedom to choose a representative inflow solution for the four-velocity u µ of the inflow, for a given magnetization sufficiently high to result in a negative energy inflow, from which the black hole rotational energy is extracted outward.…”

Section: Flow Dynamicsmentioning

confidence: 99%

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Observable Emission Features of Black Hole GRMHD Jets on Event Horizon Scales

Younsi³

et al. 2017

ApJ

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The general-relativistic magnetohydrodynamical (GRMHD) formulation for black hole-powered jets naturally gives rise to a stagnation surface, wherefrom inflows and outflows along magnetic field lines that thread the black hole event horizon originate. We derive a conservative formulation for the transport of energetic electrons which are initially injected at the stagnation surface and subsequently transported along flow streamlines. With this formulation the energy spectra evolution of the electrons along the flow in the presence of radiative and adiabatic cooling is determined. For flows regulated by synchrotron radiative losses and adiabatic cooling, the effective radio emission region is found to be finite, and geometrically it is more extended along the jet central axis. Moreover, the emission from regions adjacent to the stagnation surface is expected to be the most luminous as this is where the freshly injected energetic electrons concentrate. An observable stagnation surface is thus a strong prediction of the GRMHD jet model with the prescribed non-thermal electron injection. Future millimeter/sub-millimeter (mm/sub-mm) very-long-baseline interferometric (VLBI) observations of supermassive black hole candidates, such as the one at the center of M87, can verify this GRMHD jet model and its associated non-thermal electron injection mechanism.

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“…We adopt the well-defined model for GRMHD shock formation in accreting plasma, discussed in a series of papers (T02, T06, F07) in a formalism closely aligned with other simulations, for example, by Pu et al (2015). We consider stationary (∂ t =0) and axisymmetric (∂ f =0) ideal MHD accretion in Kerr geometry whose spacetime metric component mn g is described by the Boyer-Lindquist coordinates (t, r, θ, f) In the context of ideal GRMHD, the properties of the accreting plasma are governed by (1) the particle number conservation law, a a nu ; ( ) , where n is the proper particle number density and u α is the plasma four-velocity; (2) the equation of motion, = and m r = + P n ( ) is the relativistic enthalpy, P is the thermal gas pressure, ρ is the total energy density, and n is the plasma number density.…”

Section: Formalismmentioning

confidence: 99%

Soft X-Ray Excess From Shocked Accreting Plasma in Active Galactic Nuclei

Fukumura

Hendry

Clark

et al. 2016

ApJ

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We propose a novel theoretical model to describe the physical identity of the soft X-ray excess that is ubiquitously detected in many Seyfert galaxies, by considering a steady-state, axisymmetric plasma accretion within the innermost stable circular orbit around a black hole (BH) accretion disk. We extend our earlier theoretical investigations on general relativistic magnetohydrodynamic accretion, which implied that the accreting plasma can develop into a standing shock under suitable physical conditions, causing the downstream flow to be sufficiently hot due to shock compression. We perform numerical calculations to examine, for sets of fiducial plasma parameters, the physical nature of fast magnetohydrodynamic shocks under strong gravity for different BH spins. We show that thermal seed photons from the standard accretion disk can be effectively Compton up-scattered by the energized sub-relativistic electrons in the hot downstream plasma to produce the soft excess feature in X-rays. As a case study, we construct a three-parameter Comptonization model of inclination angle θ obs , disk photon temperature kT in , and downstream electron energy kT e to calculate the predicted spectra in comparison with a 60 ks XMM-Newton/EPIC-pn spectrum of a typical radio-quiet Seyfert 1 active galactic nucleus, Ark120. Our χ 2 -analyses demonstrate that the model is plausible for successfully describing data for both non-spinning and spinning BHs with derived ranges of 61.3 keV  kT e  144.3 keV, 21.6 eV  kT in  34.0 eV, and 17°.5  θ obs  42°.6, indicating a compact Comptonizing region of three to four gravitational radii that resembles the putative X-ray coronae.

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Steady General Relativistic Magnetohydrodynamic Inflow/Outflow Solution Along Large-Scale Magnetic Fields That Thread a Rotating Black Hole

Cited by 42 publications

References 52 publications

rHARM: ACCRETION AND EJECTION IN RESISTIVE GR-MHD

rHARM: ACCRETION AND EJECTION IN RESISTIVE GR-MHD

Observable Emission Features of Black Hole GRMHD Jets on Event Horizon Scales

Soft X-Ray Excess From Shocked Accreting Plasma in Active Galactic Nuclei

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