Global MHD Simulation of the Inner Accretion Disk in a Pseudo-Newtonian Potential

By J. Hawley, Julian Krolik. 2000

190 citations recorded by the source corpus.

We present a detailed three-dimensional magnetohydrodynamic (MHD) simulation describing the inner region of a disk accreting onto a black hole. To avoid the technical complications of general relativity, the dynamics are treated in Newtonian fashion using the pseudo-Newtonian Paczyński-Wiita potential. The disk evolves as a result of angular momentum transport that is produced naturally from MHD turbulence generated by the magnetorotational instability. We find that the resulting stress is continuous across the marginally stable orbit, in contradiction to the widely held assumption that the stress should go to zero there. As a consequence, the specific angular momentum of the matter accreted into the hole is smaller than the specific angular momentum at the marginally stable orbit. The disk exhibits large fluctuations in almost every quantity, both spatially and temporally. In particular, the ratio of stress to pressure (the local analog of the Shakura-Sunyaev α parameter) exhibits both systematic gradients and large fluctuations; from ~10-2 in the disk midplane at large radius, it rises to ~10 both at a few gas density scale heights above the plane at large radius and near the midplane well inside the plunging region. Driven in part by large-amplitude waves excited near the marginally stable orbit, both the mass accretion rate and the integrated stress exhibit large fluctuations whose Fourier power spectra are smooth "red" power laws stretching over several orders of magnitude in timescale.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/a240dc9d0fc8d0ec61b1677fe28bb4e45736ccda

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Citations in the corpus

What broad emission lines tell us about how active galactic nuclei work (2009, background): “…the development of more sophisticated programs by several groups have allowed increasingly detailed magneto-hydrodynamic (MHD) simulations of accretion flows (e.g., Hawley & Krolik 2001; Proga 2003; Anninos, Fragile, & Salmonson 2005; Ohsuga et al. 2009; Shafee et al. 2008, and references therein).”
The Dynamical Structure of Nonradiative Black Hole Accretion Flows (2002, background): “A high-resolution torus simulation (Hawley & Krolik 2001) found that the magnetic stress can remain large down to and beyond the marginally stable orbit.”
Enhanced Angular Momentum Transport in Accretion Disks (2003, background): “Hawley & Krolik (2001, 2002) investigate the evolution of a magnetized accretion torus lying near the marginally stable orbit in a pseudo-Newtonian model potential for the black hole (Paczyńsky & Wiita 1980).”
ASSESSING QUANTITATIVE RESULTS IN ACCRETION SIMULATIONS: FROM LOCAL TO GLOBAL (2011, background): “…made it possible to carry out global disk simulations of increasing complexity, as the state-of-the-art has risen from pseudo-Newtonian dynamics (Hawley & Krolik 2001; Machida & Matsumoto 2003) to full three-dimensional general relativistic physics (De Villiers & Hawley 2003; Gammie et al.…”
Broad Iron-Kα Emission Lines as a Diagnostic of Black Hole Spin (2007, result): “A comparison of this result with those of Hawley & Krolik (2001) supports the conjecture (Armitage et al. 2001; Afshordi & Paczynski 2003) that the magnetic extraction of energy and angular momentum fromwithin the ISCO (Krolik 1999; Gammie 1999) becomes less important as one considers progressively…”
A Magnetohydrodynamic Nonradiative Accretion Flow in Three Dimensions (2001, background): “A higher resolution torus simulation (Hawley & Krolik 2001) shows that the magnetic stress can remain large down to and beyond the marginally stable orbit.”
Magnetic Braking and Protostellar Disk Formation: The Ideal MHD Limit (2007, background): “Spontaneous symmetry breaking is observed in MHD simulations of black hole accretion (Hawley & Krolik 2001; Stone & Pringle 2001).”
Magnetically Driven Accretion Flows in the Kerr Metric. I. Models and Overall Structure (2003, background): “In particular, a number of pseudo-Newtonian simulations have focused on the inner edge of an accretion disk orbiting a black hole (Hawley & Krolik 2001, 2002, hereafter HK01, HK02, respectively; Armitage, Reynolds, & Chiang 2001; Armitage & Reynolds 2003; Machida & Matsumoto 2003).”
Three-dimensional Magnetohydrodynamic Simulations of Radiatively Inefficient Accretion Flows (2003, background): “Perhaps for this reason, a number of recent numerical simulations of MHD accretion flows around black holes have employed this boundary condition (e.g., Hawley 2000, 2001; Hawley & Krolik 2001, 2002; Armitage, Reynolds, & Chiang 2001; Krolik & Hawley 2002).”
THREE-DIMENSIONAL MAGNETOHYDRODYNAMIC SIMULATIONS OF CIRCUMBINARY ACCRETION DISKS: DISK STRUCTURES AND ANGULAR MOMENTUM TRANSPORT (2011, background): “Although that might be a reasonable approximation for vertically-integrated and time-averaged conditions in the main body of a disk, it becomes unrealistic for highly time-dependent turbulent accretion flows and low density regions outside the disk body(Hawley & Krolik 2001).”
Fluorescent iron lines as a probe of astrophysical black hole systems (2002, background): “Simulations of MHD accretion disks within this potential have been presented in a number of papers[124,125,131–133].”
A Unified Description of the Timing Features of Accreting X-Ray Binaries (2002, background): “…Bao and Ostgaard 1995; Takeuchi, Mineshige, & Negoro 1995), short-lived magnetic flares in the accretion-disk coronae (Poutanen & Fabian 1999), erratic injections of soft photons in a Comptonizing medium (Kazanas & Hua 1999), MHD instabilities in the accretion disks (Hawley & Krolik 2001), etc.”
Three-dimensional general relativistic radiation magnetohydrodynamical simulation of super-Eddington accretion, using a new code HARMRAD with M1 closure (2013, background): “Instead, simulations with various initial conditions lead to evolved disk states of various disk thicknesses, such as |H/R| ∼ 0.1–0.15 (Hawley & Krolik 2001; De Villiers et al. 2003; Beckwith et al. 2008b,a, 2009) and |H/R| ∼ 0.2 (Hawley & Balbus 2002; Machida et al. 2000; Martı́ & Müller 2003;…”
DIRECT CALCULATION OF THE RADIATIVE EFFICIENCY OF AN ACCRETION DISK AROUND A BLACK HOLE (2008, background): “Stimulated by this recognition, the past decade has seen many numerical simulations of global disk dynamics incorporating magnetic forces under the assumption of ideal magnetodhyrodynamics (MHD) (Hawley & Krolik 2001, 2002; Armitage et al. 2001; Reynolds & Armitage 2001; Armitage & Reynolds 2003; Ma”
Global Radiation-Magnetohydrodynamic Simulations of Black-Hole Accretion Flow and Outflow: Unified Model of Three States (2009, background): “…1991), multi-dimensional global magneto-hydrodynamics (MHD) simulations are being rather extensively performed recently as a model for the disks with low luminosities (Matsumoto 1999; Machida et al. 2000; Hawley & Krolik 2001; Koide et al. 2001; De Villiers et al. 2003; Hawley & Krolik 2006) .”
Magnetically Driven Accretion Flows in the Kerr Metric. II. Structure of the Magnetic Field (2003, methodology): “…accretion onto black holes employed codes solving the equations of pseudo-Newtonian physics, i.e. Newtonian dynamics but with a gravitational potential of the Paczyński-Wiita form (Hawley 2000; Hawley & Krolik 2001, 2002; Armitage et al. 2001; Armitage & Reynolds 2003; Machida & Matsumoto 2003).”
X-ray continuum variability of MCG-6-30-15 (2002, background): “…criticality in an accretion disc (Mineshige, Ouchi & Nishimori 1994); fluctuations in the accretion rate propagating through the disc (Lyubarskii 1997; Churazov et al. 2001; Kotov, Churazov & Gilfanov 2001) and magnetohydrodynamic instabilities in the inner accretion disc (Hawley & Krolik 2001).”
XMM-EPIC observation of MCG-6-30-15: direct evidence for the extraction of energy from a spinning black hole? (2001, background): “Nonrelativistic accretion disk simulations employing pseudoNewtonian potentials suggest that the stresses and presumably the dissipation remain fairly flat within this region (Hawley & Krolik 2001; Armitage, Reynolds & Chiang 2001).”
Hot Accretion Flows Around Black Holes (2014, background): “Early pioneers in global MHD simulations include Matsumoto & Shibata (1997), Armitage (1998), Hawley (2000), Machida et al. (2000), Stone & Pringle (2001), Hawley & Krolik (2001), and Igumenshchev & Narayan (2002).”