Shearing Box Simulations of the MRI in a Collisionless Plasma

By Prateek Sharma, Gregory W. Hammett, E. Quataert, James M. Stone. 2005

177 citations recorded by the source corpus.

We describe local shearing box simulations of turbulence driven by the magnetorotational instability (MRI) in a collisionless plasma. Collisionless effects may be important in radiatively inefficient accretion flows, such as near the black hole in the Galactic center. The MHD version of ZEUS is modified to evolve an anisotropic pressure tensor. A fluid closure approximation is used to calculate heat conduction along magnetic field lines. The anisotropic pressure tensor provides a qualitatively new mechanism for transporting angular momentum in accretion flows (in addition to the Maxwell and Reynolds stresses). We estimate limits on the pressure anisotropy due to pitch angle scattering by kinetic instabilities. Such instabilities provide an effective "collision" rate in a collisionless plasma and lead to more MHD-like dynamics. We find that the MRI leads to efficient growth of the magnetic field in a collisionless plasma, with saturation amplitudes comparable to those in MHD. In the saturated state, the anisotropic stress is comparable to the Maxwell stress, implying that the rate of angular momentum transport may be moderately enhanced in a collisionless plasma.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/2974e548f6a513881057b146655002427dc7fe67

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In Astronomy and Astrophysics

1. Ramesh Narayan
2. F. Yuan
3. E. Quataert
4. T. Johannsen
5. Gregory G. Howes
6. Abraham Loeb
7. A. Broderick
8. S. Oh

Citations in the corpus

• A characteristic scale for cold gas (2016, background): “…such as the firehose and mirror instability, which feed off pressure anisotropies, provide an effective scattering mechanism and can reduce the particle mean free paths to orders of magnitude below their Coulomb value (Sharma et al., 2006; Bale et al., 2009; Kunz, Schekochihin & Stone, 2014).”
• Hot Accretion Flows Around Black Holes (2014, methodology): “The nonlinear development of the kinetic MRI has been studied using numerical simulations based on a fluid model with kinetic effects added (Sharma et al. 2006) as well as the more precise particle-in-cell technique (Riquelme et al. 2012).”
• ASTROPHYSICAL GYROKINETICS: KINETIC AND FLUID TURBULENT CASCADES IN MAGNETIZED WEAKLY COLLISIONAL PLASMAS (2007, methodology): “…5, ERMHD— § 7, HRMHD—Appendix E) as well as with the numerical studies based on various Landau fluid (Snyder et al. 1997; Goswami et al. 2005; Ramos 2005; Sharma et al. 2006, 2007; Passot & Sulem 2007) and gyrofluid (Hammett et al. 1991; Dorland & Hammett 1993; Snyder & Hammett 2001;…”
• Electron Heating in Hot Accretion Flows (2007, background): “Our recent work has focused on the evolution of the MRI in collisionless plasmas (Quataert et al. 2002; Sharma et al. 2003; Sharma et al. 2006, hereafter S06; for related work see Balbus 2004; Krolik & Zweibel 2006).”
• INCORPORATING KINETIC PHYSICS INTO A TWO-FLUID SOLAR-WIND MODEL WITH TEMPERATURE ANISOTROPY AND LOW-FREQUENCY ALFVÉN-WAVE TURBULENCE (2011, methodology): “A similar approach was employed by Sharma et al. (2006) in numerical simulations of accretion flows around black holes.”
• EVIDENCE FOR LOW BLACK HOLE SPIN AND PHYSICALLY MOTIVATED ACCRETION MODELS FROM MILLIMETER-VLBI OBSERVATIONS OF SAGITTARIUS A* (2010, background): “The applicability of the MHD prescription to Sgr A* is still unclear, where the accretion rate is sufficiently low that non-MHD effects may become important (Sharma et al. 2006, 2007).”