Properties of the Turbulence Associated with Electron-only Magnetic Reconnection in Earth’s Magnetosheath

Stawarz, J. E.; Eastwood, J. P.; Phan, T. D.; Gingell, Imogen; Shay, M. A.; Burch, J. L.; Ergun, R. E.; Giles, B. L.; Gershman, D. J.; Contel, O. Le; Lindqvist, Per‐Arne; Russell, C. T.; Strangeway, R. J.; Torbert, R. B.; Argall, M. R.; Fischer, D.; Magnes, W.; Franci, Luca

doi:10.3847/2041-8213/ab21c8

Cited by 94 publications

(122 citation statements)

References 46 publications

Supporting

Mentioning

103

Contrasting

Unclassified

Order By: Relevance

“…The essential physical result is that if the initial collapsing solution is not sufficiently anisotropic when its thickness is above the ion scales, the collapse continues down to a thickness well below the ion scale, and electron-only reconnection will occur. Remarkably (considering the formal limitation of KREHM to low β), we will see that our model seems to agree rather well with the magnetosheath observations of electron-only reconnection (Phan et al 2018;Stawarz et al 2019).…”

Section: Introductionsupporting

confidence: 82%

The onset of electron-only reconnection

Mallet

2020

J. Plasma Phys.

View full text Add to dashboard Cite

Motivated by recent observations of ‘electron-only’ magnetic reconnection, without an ion-scale sheet or ion outflows, in both the Earth’s magnetosheath and in numerical simulations, we study the formation and reconnection of electron-scale current sheets at low plasma $\unicode[STIX]{x1D6FD}$ . We first show that ideal sheets collapse to thicknesses much smaller than the ion scales, by deriving an appropriate analogue of the Chapman–Kendall collapse solution. Second, we show that, in practice, reconnection onset happens in these collapsing sheets once they reach a critical aspect ratio, because the tearing instability then becomes faster than their collapse time scale. We show that this can happen for sheet thicknesses larger than the ion scale or at only a few times the electron scale, depending on plasma parameters and the aspect ratio of the collapsing structure, thereby unifying the usual picture of ion-coupled reconnection and the new regime of electron-only reconnection. We derive relationships between plasma $\unicode[STIX]{x1D6FD}$ , ion-to-electron temperature ratio, the aspect ratio, electron outflow velocity and the final thickness of the sheets, and thus determine under what circumstances electron-scale sheets form and reconnect.

show abstract

Section: Introductionsupporting

confidence: 82%

The onset of electron-only reconnection

Mallet

2020

J. Plasma Phys.

View full text Add to dashboard Cite

show abstract

“…Analysis of the location of active reconnection sites associated with shock waves has shown that the phenomenon is localized to the shock and thus separated from turbulent reconnection occurring in the magnetosheath (Phan et al, ; Stawarz et al, ). This is consistent with the expectations set by hybrid simulations of Earth's bow shock presented by Gingell et al (), which show that reconnection sites are generated on sub‐ion timescales in a transient, localized transition region.…”

Section: Discussionmentioning

confidence: 99%

Statistics of Reconnecting Current Sheets in the Transition Region of Earth's Bow Shock

et al. 2020

Self Cite

View full text Add to dashboard Cite

We have conducted a comprehensive survey of burst mode observations of Earth's bow shock by the Magnetospheric Multiscale mission to identify and characterize current sheets associated with collisionless shocks, with a focus on those containing fast electron outflows, a likely signature of magnetic reconnection. The survey demonstrates that these thin current sheets are observed within the transition region of approximately 40% of shocks within the burst mode data set of Magnetospheric Multiscale. With only small apparent bias toward quasi-parallel shock orientations and high Alfvén Mach numbers, the results suggest that reconnection at shocks is a universal process, occurring across all shock orientations and Mach numbers. On examining the distributions of current sheet properties, we find no correlation between distance from the shock, sheet width, or electron jet speed, though the relationship between electron and ion jet speed supports expectations of electron-only reconnection in the region. Furthermore, we find that robust heating statistics are not separable from background fluctuations, and thus, the primary consequence of reconnection at shocks is in relaxing the topology of the disordered magnetic field in the transition region.

show abstract

“…It is interesting to analyze this result in light of recent MMS observations of so-called electron-only reconnection in the Earth's magnetosheath (Phan et al 2018;Stawarz et al 2019). In Boldyrev & Loureiro (2019) we have estimated that the decoupling of the ions in these events requires λ/d e ≪ d i /d e or λ/d e ≪ (d i /d e ) 2/3 depending on whether one assumes a tanh(x/λ) or sin(x/λ) magnetic field profile for the reconnecting field B ξ (x) in the eddy.…”

Section: Reconnection At Kinetic Scalesmentioning

confidence: 99%

Nonlinear Reconnection in Magnetized Turbulence

Loureiro

Boldyrev

2020

ApJ

View full text Add to dashboard Cite

Recent analytical works on strong magnetized plasma turbulence have hypothesized the existence of a range of scales where the tearing instability may govern the energy cascade. In this paper, we estimate the conditions under which such tearing may give rise to full nonlinear magnetic reconnection in the turbulent eddies, thereby enabling significant energy conversion and dissipation. When those conditions are met, a new turbulence regime is accessed where reconnection-driven energy dissipation becomes common, rather than the rare feature that it must be when they are not.

show abstract

Properties of the Turbulence Associated with Electron-only Magnetic Reconnection in Earth’s Magnetosheath

Cited by 94 publications

References 46 publications

The onset of electron-only reconnection

The onset of electron-only reconnection

Statistics of Reconnecting Current Sheets in the Transition Region of Earth's Bow Shock

Nonlinear Reconnection in Magnetized Turbulence

Contact Info

Product

Resources

About