Simulations of magnetized discs around black holes: Effects of black hole spin, disc thickness and magnetic field geometry

By R. Penna, J. McKinney, Ramesh Narayan, A. Tchekhovskoy, Rebecca Shafee, J. K. H. CfA, StanfordKIPAC, Harvard Center for Brain Science. 2010

247 citations recorded by the source corpus.

The standard general relativistic model of a razor-thin accretion disc around a black hole, developed by Novikov & Thorne (NT) in 1973, assumes the shear stress vanishes at the radius of the innermost stable circular orbit (ISCO) and that, outside the ISCO, the shear stress is produced by an effective turbulent viscosity. However, astrophysical accretion discs are not razor thin; it is uncertain whether the shear stress necessarily vanishes at the ISCO, and the magnetic field, which is thought to drive turbulence in discs, may contain large-scale structures that do not behave like a simple local scalar viscosity. We describe 3D general relativistic magnetohydrodynamic simulations of accretion discs around black holes with a range of spin parameters, and we use the simulations to assess the validity of the NT model. Our fiducial initial magnetic field consists of multiple (alternating polarity) poloidal field loops whose shape is roughly isotropic in the disc in order to match the isotropic turbulence expected in the poloidal plane. For a thin disc with an aspect ratio |h/r| ∼ 0.07 around a non-spinning black hole, we find a decrease in the accreted specific angular momentum of 2.9 per cent relative to the NT model and an excess luminosity from inside the ISCO of 3.5 per cent. The deviations in the case of spinning black holes are also of the same order. In addition, the deviations decrease with decreasing |h/r|. We therefore conclude that magnetized thin accretion discs in X-ray binaries in the thermal/high-soft spectral state ought to be well described by the NT model, especially at luminosities below 30 per cent of Eddington where we expect a very small disc thickness |h/r| ≲ 0.05. We use our results to determine the spin equilibrium of black hole accretion discs with a range of thicknesses and to determine how electromagnetic stresses within the ISCO depend upon black hole spin and disc thickness. We find that the electromagnetic stress and the luminosity inside the ISCO depend on the assumed initial magnetic field geometry. We consider a second geometry with field lines following density contours, which for thin discs leads to highly radially elongated magnetic field lines. This gives roughly twice larger deviations from NT for both the accreted specific angular momentum and the luminosity inside the ISCO. Lastly, we find that the disc's corona (including any wind or jet) introduces deviations from NT in the specific angular momentum that are comparable to those contributed by the disc component, while the excess luminosity of bound gas from within the ISCO is dominated by only the disc component. Based on these indications, we suggest that differences in results between our work and other similar work are due to differences in the assumed initial magnetic field geometry as well as the inclusion of disc gas versus all the gas when comparing the specific angular momentum from the simulations with the NT model.

Subfields: Astronomy and Astrophysics, Biomedical Engineering

View Paper: https://www.semanticscholar.org/paper/ab94fcca6b33dd6335b0ffc5b0625ec3d087b0b4

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Biomedical Engineering

Citations in the corpus

LOCAL STUDY OF ACCRETION DISKS WITH A STRONG VERTICAL MAGNETIC FIELD: MAGNETOROTATIONAL INSTABILITY AND DISK OUTFLOW (2012, methodology): “…the simulations are initialized either with single/multiple poloidal magnetic loops for a thick disk torus (Hawley 2000; De Villiers et al. 2003; Penna et al. 2010), or with pure toroidal magnetic field in a thin power-law disk (Fromang & Nelson 2006; Beckwith et al. 2011; Flock et al. 2011).”
Prograde and retrograde black holes: whose jet is more powerful? (2012, unknown): “0.05) radiatively-efficient discs (Penna et al. 2010).”
Precise mass and spin measurements for a stellar-mass black hole through X-ray timing: the case of GRO J1655-40 (2013, background): “Several different edges can be defined (Krolik & Hawley 2002; Abramowicz et al. 2010; Penna et al. 2010) and in all cases their minimum value lies in the vicinity of the ISCO.”
Measuring Black Hole Spin Using X-Ray Reflection Spectroscopy (2013, background): “This basic behavior is confirmed by magnetohydrodynamic simulations of thin accretion disks (Reynolds & Fabian 2008; Penna et al. 2010).”
ASSESSING QUANTITATIVE RESULTS IN ACCRETION SIMULATIONS: FROM LOCAL TO GLOBAL (2011, background): “It is worth noting that Penna et al. (2010) proposed an alternative definition of inflow equilibrium time at radius R, specifically 2R/〈vR〉 (rather than ∫ dR/〈vR〉), solely in terms of a general scaling argument.”
Numerical simulations of super-critical black hole accretion flows in general relativity (2013, methodology): “…been described in the literature (e.g., De Villiers et al. 2003; Gammie et al. 2003; Anninos et al. 2005; Del Zanna et al. 2007; Shafee et al. 2008; Penna et al. 2010; Tchekhovskoy et al. 2010a,b; Narayan et al. 2010; Noble et al. 2011; Tchekhovskoy et al. 2011; Tchekhovskoy & McKinney 2012a;…”
The spin of the black hole microquasar XTE J1550−564 via the continuum-fitting and Fe-line methods (2010, methodology): “The upper luminosity threshold ensures the disc is geometrically thin (McClintock et al. 2006; Penna et al. 2010), as required by the model.”
EVIDENCE FOR LOW BLACK HOLE SPIN AND PHYSICALLY MOTIVATED ACCRETION MODELS FROM MILLIMETER-VLBI OBSERVATIONS OF SAGITTARIUS A* (2010, background): “…magnetohydrodynamic and radiative-hydrodynamic simulations playing a central role (De Villiers et al. 2005; McKinney 2006; Hawley & Krolik 2006; Beckwith et al. 2008; McKinney & Blandford 2009; Tchekhovskoy et al. 2010; Dexter et al. 2010; Penna et al. 2010; Kurosawa & Proga 2009).”
Three-dimensional general relativistic radiation magnetohydrodynamical simulation of super-Eddington accretion, using a new code HARMRAD with M1 closure (2013, methodology): “0.3, the disk cools efficiently, and the inner accretion disk can collapse into an optically thick geometrically thin accretion disk (Shakura & Sunyaev 1973; Novikov & Thorne 1973; Thorne 1974; Esin et al. 1997, 1998; Martı́ & Müller 2003; McClintock & Remillard 2006; Done et al. 2007).”
BLAZARS IN THE FERMI ERA: THE OVRO 40 m TELESCOPE MONITORING PROGRAM (2010, methodology): “Full three-dimensional (non-axisymmetric) magnetohydrodynamic relativistic simulations are now being carried out that enable detailed interpretation of the observations over the whole electromagnetic spectrum(e.g. McKinney & Blandford 2009; Penna et al. 2010).”
Superradiance (2015, methodology): “Both the (mass-independent) shape of the iron Kα line seen in reflection [628] and the thermal emission from the inner edge of the disc [629] – assumed to be the ISCO [630, 631] – are commonly employed for both stellar mass BHs in binaries and supermassive BHs in active galactic nuclei (although the”
A Reconnection Switch to Trigger gamma-Ray Burst Jet Dissipation (2010, background): “…applicable to a neutrino-dominated accretion disc that takes on a quite thin geometry near a rotating BH where the jet is launched [see e.g. Kohri et al. (2005) and Chen & Beloborodov (2007), and for simulations of such magnetized thin discs, see e.g. Shafee et al. (2008) and Penna et al. (2010)].”
Black Hole Spin via Continuum Fitting and the Role of Spin in Powering Transient Jets (2013, methodology): “To answer this question, geometrically thin accretion disks around black holes have been simulated by a number of authors (Shafee et al. 2008a; Noble & Krolik 2009; Penna et al. 2010) using state-of-the-art GRMHD codes.”
The Event Horizon General Relativistic Magnetohydrodynamic Code Comparison Project (2019, methodology): “…important for large parameter surveys as in Mościbrodzka et al. (2016a), who applied HARM3D with 96×96×64 cells and for long time evolutions as in Penna et al. (2010), who ran a large suite of simulations with resolutions of effective 256×64×64 cells (accounting for the restricted f pD = ).”
Testing the Kerr Black Hole Hypothesis Using X-Ray Reflection Spectroscopy (2016, background): “Similar disks are thought to form when the source is in the thermal state with an accretion luminosity between a few percent and about 30% of its Eddington limit (McClintock et al. 2006; Penna et al. 2010; Steiner et al. 2010).”
The Masses and Spins of Neutron Stars and Stellar-Mass Black Holes (2014, background): “Currently, the most convincing relativistic line profile and best data are from an observation of Serpens X-1 with NuSTAR, which give rNS ≤ 15 km (and thus a surface redshift zNS ≥ 0.16 for MNS = 1.4 M⊙) for a broad set of fits, and rNS ≤ 12.6 km if the disk extends to the ISCO ([283]).”
Hot Accretion Flows Around Black Holes (2014, result): “This is in contrast to the case of thin disks, where the flow changes dramatically across the ISCO (Reynolds & Fabian 2008, Shafee et al. 2008, Penna et al. 2010, but see Noble et al. 2010).”
General relativistic magnetohydrodynamic simulations of magnetically choked accretion flows around black holes (2012, methodology): “By contrast, the same table diagnostics for the multi-field loop thin (θd ∼ 0.07) disk model A0HR07 in Penna et al. (2010) give αb ∼ αb,eff ∼ 0.04 for r = 7–9rg, so α-disk theory works quite well for those multi-loop field thin disk models.”