Asymmetric evolution of magnetic reconnection in collisionless accretion disk

Abstract

An evolution of a magnetic reconnection in a collisionless accretion disk is investigated using a 2.5 dimensional hybrid code simulation. In astrophysical disks, magnetorotational instability (MRI) is considered to play an important role by generating turbulence in the disk and contributes to an effective angular momentum transport through a turbulent viscosity. Magnetic reconnection, on the other hand, also plays an important role on the evolution of the disk through a dissipation of a magnetic field enhanced by a dynamo effect of MRI. In this study, we developed a hybrid code to calculate an evolution of a differentially rotating system. With this code, we first confirmed a linear growth of MRI. We also investigated a behavior of a particular structure of a current sheet, which would exist in the turbulence in the disk. From the calculation of the magnetic reconnection, we found an asymmetric structure in the out-of-plane magnetic field during the evolution of reconnection, which can be understood by a coupling of the Hall effect and the differential rotation. We also found a migration of X-point whose direction is determined only by an initial sign of J_0 \times Ω_0, where J_0 is the initial current density in the neutral sheet and Ω_0 is the rotational vector of the background Keplerian rotation. Associated with the migration of X-point, we also found a significant enhancement of the perpendicular magnetic field compared to an ordinary MRI. MRI-Magnetic reconnection coupling and the resulting magnetic field enhancement can be an effective process to sustain a strong turbulence in the accretion disk and to a transport of angular momentum.

arXiv comment21 pages, 10 figures

References in corpus (10)

• Linear Analysis of the Hall Effect in Protostellar Disks
• Shearing Box Simulations of the MRI in a Collisionless Plasma
• The Effect of the Hall Term on the Nonlinear Evolution of the Magnetorotational Instability: I. Local Axisymmetric Simulations
• The Magnetorotational Instability in a Collisionless Plasma
• Saturation and Thermalization of the Magnetorotational Instability: Recurrent Channel Flows and Reconnections
• Local 2D Particle-in-cell simulations of the collisionless MRI
• Particle Acceleration during Magnetorotational Instability in a Collisionless Accretion Disk
• The inner structure of collisionless magnetic reconnection: The electron-frame dissipation measure and Hall fields
• The Relation between Ion Temperature Anisotropy and Formation of Slow Shocks in Collisionless Magnetic Reconnection
• Finite Larmor Radius Effects on the Magnetorotational Instability

Cited by in corpus (3)

• Stochastic Particle Acceleration in Turbulence Generated by the Magnetorotational Instability
• Pressure tensor in the presence of velocity shear: stationary solutions and self-consistent equilibria
• On properties of Velikhov-Chandrasekhar MRI in ideal and non-ideal plasma