Reconnection in weakly stochastic<i>B</i>-fields in 2D

Kulpa-Dybeł, K.; Kowal, Grzegorz; Otmianowska-Mazur, K.; Lazarian, A.; Vishniac, Ethan T.

doi:10.1051/0004-6361/200913218

Cited by 17 publications

(17 citation statements)

References 45 publications

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“…This is really a case of small-scale magnetic reconnection, as considered in our previous Section 5.3, and not directly relevant to the issue of reconnection of large-scale flux tubes. Two other numerical studies have recently been made of large-scale magnetic reconnection in 2D, by Loureiro et al (2009) and Kulpa-Dybeł et al (2010), which reach different conclusions. On the one hand, Loureiro et al (2009) had a better resolution but used periodic boundary conditions, which strongly constrain the ability to do averaging of the reconnection rate and the attainment of the steady state for reconnection.…”

Section: D Mhd Turbulence and Reconnectionmentioning

confidence: 98%

“…They inferred from their data that the 2D turbulent reconnection rate may be independent of resistivity. On the other hand, Kulpa-Dybeł et al (2010) used smaller data cubes but longer averaging, which is enabled by their outflow boundary conditions. They concluded that the reconnection does depend on resistivity and therefore is slow.…”

Section: D Mhd Turbulence and Reconnectionmentioning

confidence: 99%

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Fast Magnetic Reconnection and Spontaneous Stochasticity

Eyink

Lazarían²,

Vishniac

2011

ApJ

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183

260

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Magnetic field lines in astrophysical plasmas are expected to be frozen-in at scales larger than the ion gyroradius. The rapid reconnection of magnetic-flux structures with dimensions vastly larger than the gyroradius requires a breakdown in the standard Alfvén flux-freezing law. We attribute this breakdown to ubiquitous MHD plasma turbulence with power-law scaling ranges of velocity and magnetic energy spectra. Lagrangian particle trajectories in such environments become "spontaneously stochastic," so that infinitely many magnetic field lines are advected to each point and must be averaged to obtain the resultant magnetic field. The relative distance between initial magnetic field lines which arrive at the same final point depends upon the properties of two-particle turbulent dispersion. We develop predictions based on the phenomenological Goldreich & Sridhar theory of strong MHD turbulence and on weak MHD turbulence theory. We recover the predictions of the Lazarian & Vishniac theory for the reconnection rate of large-scale magnetic structures. Lazarian & Vishniac also invoked "spontaneous stochasticity," but of the field lines rather than of the Lagrangian trajectories. More recent theories of fast magnetic reconnection appeal to microscopic plasma processes that lead to additional terms in the generalized Ohm's law, such as the collisionless Hall term. We estimate quantitatively the effect of such processes on the inertial-range turbulence dynamics and find them to be negligible in most astrophysical environments. For example, the predictions of the Lazarian & Vishniac theory are unchanged in Hall MHD turbulence with an extended inertial range, whenever the ion skin depth δ i is much smaller than the turbulent integral length or injection-scale L i .

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Section: D Mhd Turbulence and Reconnectionmentioning

confidence: 98%

Section: D Mhd Turbulence and Reconnectionmentioning

confidence: 99%

Fast Magnetic Reconnection and Spontaneous Stochasticity

Eyink

Lazarían²,

Vishniac

2011

ApJ

Self Cite

183

260

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“…Loureiro et al (2009) studied two-dimensional turbulent reconnection performing high-resolution simulations in a periodic box for Lundquist numbers up to 5 × 10 4 concluding the existence of a critical threshold of the injection rate above which the reconnection rate is enhanced. Kulpa-Dybeł et al (2010) performed numerical simulations of the LV99 model in two dimensions showing that the relations between the reconnection speed and turbulence properties are different than those predicted by the LV99 model, and the reconnection is not fast in the presence of turbulence, since it still depends on the resistivity. In any case, it is obvious that the difference in physics of magnetic turbulence in 2D and 3D makes two dimentional studies a subject of pure academic interest.…”

Section: A Testing Lv99 Predictions With Mhd Codesmentioning

confidence: 99%

3D turbulent reconnection: Theory, tests, and astrophysical implications

Lazarían¹,

et al. 2020

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Magnetic reconnection, topological change in magnetic fields, is a fundamental process in magnetized plasmas. It is associated with energy release in regions of magnetic field annihilation, but this is only one facet of this process. Astrophysical fluid flows normally have very large Reynolds numbers and are expected to be turbulent, in agreement with observations. In strong turbulence magnetic field lines constantly reconnect everywhere and on all scales, thus making magnetic reconnection an intrinsic part of the turbulent cascade. We note in particular that this is inconsistent with the usual practice of regarding magnetic field lines as persistent dynamical elements. A number of theoretical, numerical, and observational studies starting with the Lazarian & Vishniac 1999 paper proposed that 3D turbulence makes magnetic reconnection fast and that magnetic reconnection and turbulence are intrinsically connected. In particular, we discuss the dramatic violation of the textbook concept of magnetic flux-freezing in the presence of turbulence. We demonstrate that in the presence of turbulence the plasma effects are subdominant to turbulence as far as the magnetic reconnection is concerned. The latter fact justifies an MHD-like treatment of magnetic reconnection on all scales much larger than the relevant plasma scales. We discuss numerical and observational evidence supporting the turbulent reconnection model. In particular, we demonstrate that the tearing reconnection is suppressed in 3D and, unlike the 2D settings, 3D reconnection induces turbulence that makes magnetic reconnection independent of resistivity. We show that turbulent reconnection dramatically affects key astrophysical processes, e.g. star formation, turbulent dynamo, acceleration of cosmic rays. We provide criticism of the concept of "reconnection-mediated turbulence" and explain why turbulent reconnection is very different from enhanced turbulent resistivity and hyper-resistivity, and why the latter have fatal conceptual flaws.

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“…3 A comparison between 3D and 2D reconnection in the presence of turbulence is made in Kulpa-Dybe" et al (2010). This work confirmed that the reconnection does depend on the dimensions of the system with the rate of 2D reconnection showing dependence on resistivity.…”

Section: Testing Of Lazarian and Vishniac 99 Modelmentioning

confidence: 56%

Fast magnetic reconnection and energetic particle acceleration

Lazarían

Kowal

Vishniac

et al. 2011

Planetary and Space Science

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a b s t r a c tOur numerical simulations show that the reconnection of magnetic field becomes fast in the presence of weak turbulence in the way consistent with the Lazarian and Vishniac (1999) model of fast reconnection. We trace particles within our numerical simulations and show that the particles can be efficiently accelerated via the first order Fermi acceleration. We discuss the acceleration arising from reconnection as a possible origin of the anomalous cosmic rays measured by Voyagers.

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Reconnection in weakly stochasticB-fields in 2D

Cited by 17 publications

References 45 publications

Fast Magnetic Reconnection and Spontaneous Stochasticity

Fast Magnetic Reconnection and Spontaneous Stochasticity

3D turbulent reconnection: Theory, tests, and astrophysical implications

Fast magnetic reconnection and energetic particle acceleration

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