Electron-only Reconnection in Kinetic-Alfvén Turbulence

Vega, Cristian; Roytershteyn, V.; Delzanno, Gian Luca; Boldyrev, Stanislav

doi:10.3847/2041-8213/ab7eba

Cited by 30 publications

(21 citation statements)

References 36 publications

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“…Relativistic turbulence has been recently studied as a mechanism of particle acceleration that is alternative or complementary to previously considered particle ener-gization by shocks (e.g., Marcowith et al 2016) or magnetic reconnection (e.g., Guo et al 2020;Drake et al 2013). (In fact, reconnection is an inherent part of magnetic plasma turbulence (e.g., Loureiro & Boldyrev 2017;Mallet et al 2017a,b;Loureiro & Boldyrev 2018;Vech et al 2018;Walker et al 2018;Dong et al 2018;Boldyrev & Loureiro 2019;Vega et al 2020) and it plays significant role at the initial stages of particle acceleration (e.g., Comisso & Sironi 2019).) In the present work, we have argued that magnetically dominated relativistic turbulence quickly evolves into the state of mildly relativistic turbulence of relativistically hot plasma.…”

Section: Discussionmentioning

confidence: 99%

Turbulence and particle acceleration in a relativistic plasma

Vega,

Boldyrev,

Roytershteyn

et al. 2021

Preprint

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In a collisionless plasma, the energy distribution function of plasma particles can be strongly affected by turbulence, in particular, it can develop a non-thermal power-law tail at large energies. We argue that turbulence with initially relativistically strong magnetic perturbations (magnetization parameter σ 1) quickly evolves into a state with ultra-relativistic plasma temperature but mildly relativistic turbulent fluctuations. We present a phenomenological and numerical study suggesting that in this case, the exponent α in the power-law particle energy distribution function, f (γ)dγ ∝ γ −α dγ, depends on magnetic compressibility of turbulence. Our analytic prediction for the scaling exponent α is in good agreement with the numerical results.

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Section: Discussionmentioning

confidence: 99%

Turbulence and particle acceleration in a relativistic plasma

Vega,

Boldyrev,

Roytershteyn

et al. 2021

Preprint

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“…These observations meet every observational criterion for an EDR except the ion response one might expect in traditional magnetic reconnection (Phan et al., 2018). Two mechanisms have been proposed for this process: low frequency, high amplitude waves (specifically below the lower hybrid frequency; Vega et al., 2020; R. Wang et al., 2018), and the current sheet having a small length (in the L direction) to width (in the N direction) ratio (Mallett, 2020, Pyakurel et al., 2019). However, due to few observations and the disparate nature and rarity of “electron‐only” reconnection, a consensus on their origin or nature has not yet been established.…”

Section: Introductionmentioning

confidence: 99%

Electron‐Only Tail Current Sheets and Their Temporal Evolution

Hubbert

Russell

et al. 2021

Geophysical Research Letters

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The Earth's magnetotail contains a current sheet separating the anti‐Sunward field of the southern lobe from the sunward‐pointing northern lobe. Herein, we report tail current sheets that are supported only by electron currents. We examine one electron‐only current sheet in detail and briefly discuss 10 others. Three current sheets are interpreted in terms of the time‐evolution of reconnection onset. These current sheets show evidence of parallel electron heating, perpendicular ion heating, and current sheet expansion. These features are consistent with electron and ion behavior during traditional “electron‐ion” reconnection. Ground‐based and in‐situ data show that electron‐ion reconnection occurs shortly after each “pre‐ion reconnection” electron‐only reconnection event. This suggests that electron‐only reconnection can act as a precursor to electron‐ion reconnection. We note that five events occur shortly after a period of electron‐ion reconnection, which suggests that electron‐only reconnection is more than merely a precursor to ion reconnection.

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“…Examples are the ionosphere [1,2], the Earth's magnetosheath [3], the solar corona [4,5] and some instances of the solar wind [6,7]. Turbulence may play a role in structure formation, energy dissipation, magnetic reconnection, heat conduction, and other processes relevant for the dynamics and thermodynamics of such systems [6,[8][9][10][11][12][13][14][15][16]. Despite vigorous investigation, the nature of turbulent fluctuations in low beta regimes remains incompletely understood and continues to attract considerable interest [3,[17][18][19][20].…”

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confidence: 99%

Dynamic Phase Alignment in Inertial Alfvén Turbulence

et al. 2020

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In weakly-collisional plasma environments with sufficiently low electron beta, Alfvénic turbulence transforms into inertial Alfvénic turbulence at scales below the electron skin-depth, k ⊥ de 1. We argue that, in inertial Alfvénic turbulence, both energy and generalized kinetic helicity exhibit direct cascades. We demonstrate that the two cascades are compatible due to the existence of a strong scale-dependence of the phase alignment angle between velocity and magnetic field fluctuations, with the phase alignment angle scaling as cos α k ∝ k −1 ⊥ . The kinetic and magnetic energy spectra scale as ∝ k, respectively. As a result of the dual direct cascade, the generalizedhelicity spectrum scales as ∝ k −5/3 ⊥ , implying progressive balancing of the turbulence as the cascade proceeds to smaller scales in the k ⊥ de 1 range. Turbulent eddies exhibit a phase-space anisotropy k ∝ k 5/3 ⊥ , consistent with critically-balanced inertial Alfvén fluctuations. Our results may be applicable to a variety of geophysical, space, and astrophysical environments, including the Earth's magnetosheath and ionosphere, solar corona, non-relativistic pair plasmas, as well as to strongly rotating non-ionized fluids.

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Electron-only Reconnection in Kinetic-Alfvén Turbulence

Cited by 30 publications

References 36 publications

Turbulence and particle acceleration in a relativistic plasma

Turbulence and particle acceleration in a relativistic plasma

Electron‐Only Tail Current Sheets and Their Temporal Evolution

Dynamic Phase Alignment in Inertial Alfvén Turbulence

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