Statistics of Reconnection-driven Turbulence

Author(s)

Kowal, Grzegorz ; Falceta-Goncalves, Diego A. ; Lazarian, Alex ; Vishniac, Ethan T.

• Document type: Journal article
• Source: ASTROPHYSICAL JOURNAL; v. 838, n. 2 APR 1 2017.
• Web of Science Citations: 17

Abstract

Magnetic reconnection is a process that changes magnetic field topology in highly conducting fluids. Within the standard Sweet-Parker model, this process would be too slow to explain observations (e.g., solar flares). In reality, the process must be ubiquitous as astrophysical fluids are magnetized and motions of fluid elements necessarily entail crossing of magnetic frozen-in field lines and magnetic reconnection. In the presence of turbulence, the reconnection is independent of microscopic plasma properties and may be much faster than previously thought, as proposed in Lazarian \& Vishniac and tested in Kowal et al. However, the considered turbulence in the LazarianVishniac model was imposed externally. In this work, we consider reconnection-driven magnetized turbulence in realistic three-dimensional geometry initiated by stochastic noise. We demonstrate through numerical simulations that the stochastic reconnection is able to self-generate turbulence through interactions between the reconnection outflows. We analyze the statistical properties of velocity fluctuations using power spectra and anisotropy scaling in the local reference frame, which demonstrates that the reconnection produces Kolmogorov-like turbulence, compatible with the Goldreich \& Sridhar model. Anisotropy statistics are, however, strongly affected by the dynamics of flows generated by the reconnection process. Once the broad turbulent region is formed, the typical anisotropy scalingl. l(parallel to) alpha l(perpendicular to)(2/3)is formed, especially for high resolution models, where the broader range of scales is available. The decay of reconnection outflows to turbulent-like fluctuations, characterized by different anisotropy scalings, strongly depends on the beta plasma parameter. Moreover, the estimated reconnection rates are weakly dependent on the model resolution, suggesting that no external processes are required to make reconnection fast. (AU)

• FAPESP's process: 13/04073-2 - Magnetic reconnection and related processes in collisional and collisionless astrophysical plasmas: from solar flares to extragalactic sources
• Grantee: Grzegorz Kowal
• Support type: Research Grants - Young Investigators Grants
• FAPESP's process: 13/18815-0 - Magnetic reconnection and related processes in collisional and collisionless astrophysical plasmas: from solar flares to extragalactic sources
• Grantee: Grzegorz Kowal
• Support type: Scholarships in Brazil - Young Researchers
• FAPESP's process: 13/10559-5 - Investigation of high energy and plasma astrophysics phenomena: theory, numerical simulations, observations, and instrument development for the Cherenkov Telescope Array (CTA)
• Grantee: Elisabete Maria de Gouveia Dal Pino
• Support type: Research Projects - Thematic Grants