Two-stage bulk electron heating in the diffusion region of anti-parallel symmetric reconnection

Lê, A.; Egedal, J.; Daughton, W.

doi:10.1063/1.4964768

Cited by 21 publications

(26 citation statements)

References 36 publications

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“…The points are colored according to the dimensionless temperature of upstream electrons (the corresponding colorbar is to the right of panel (c)), ranging from non-relativistic (θ e ∼ 10 −4 ) to ultra-relativistic (θ e ∼ 10 3 ) values. In agreement with earlier studies of non-relativistic reconnection by Dahlin et al (2014) and Le et al (2016), we find that the total electron heating efficiency at low β i is a decreasing function of mass ratio. For the realistic mass ratio, at low β i the total heating fraction M T e,tot ≈ 0.016 is in good agreement with the observed value in the magnetopause, M T e,tot = 0.017 (Phan et al 2013).…”

Section: Dependence Of Inflow and Outflow Velocity On β Isupporting

confidence: 92%

“…This statement can be further justified by considering electron energization in the diffusion region as the main source of irreversible electron heating, following Le et al (2016). In the diffusion region, the electron energy will increase by eE rec e , where E rec ∼ 0.1(v A /c)B 0 is the reconnection electric field (assuming a reconnection inflow rate of ∼ 0.1 v A /c, see Fig.…”

Section: Dependence Of Inflow and Outflow Velocity On β Imentioning

confidence: 99%

“…Electron heating by reconnection in the non-relativistic limit (σ i 1) has been studied extensively, both theoretically and by means of PIC simulations, in the context of the solar wind, Earth's magnetotail, and laboratory plasmas (Hoshino et al 2001;Jaroschek et al 2004;Loureiro et al 2013;Schoeffler et al 2011Schoeffler et al , 2013Shay et al 2014;Dahlin et al 2014;Daughton et al 2014;Li et al 2015;Haggerty et al 2015;Numata & Loureiro 2015;Le et al 2016;Li et al 2017). Though less commonly studied, relativistic reconnection (i.e., σ i 1) in electron-proton plasmas has also received some attention in recent years Guo et al 2016).…”

Section: Introductionmentioning

confidence: 99%

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Electron and Proton Heating in Transrelativistic Magnetic Reconnection

Rowan

Sironi

Narayan

2017

ApJ

130

134

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Hot collisionless accretion flows, such as the one in Sgr A * at our Galactic center, provide a unique setting for the investigation of magnetic reconnection. Here, protons are non-relativistic while electrons can be ultra-relativistic. By means of two-dimensional particle-in-cell simulations, we investigate electron and proton heating in the outflows of trans-relativistic reconnection (i.e., σ w ∼ 0.1 − 1, where the magnetization σ w is the ratio of magnetic energy density to enthalpy density). For both electrons and protons, we find that heating at high β i (here, β i is the ratio of proton thermal pressure to magnetic pressure) is dominated by adiabatic compression ("adiabatic heating"), while at low β i it is accompanied by a genuine increase in entropy ("irreversible heating"). For our fiducial σ w = 0.1, the irreversible heating efficiency at β i 1 is nearly independent of the electron-to-proton temperature ratio T e /T i (which we vary from 0.1 up to 1), and it asymptotes to ∼ 2% of the inflowing magnetic energy in the low-β i limit. Protons are heated more efficiently than electrons at low and moderate β i (by a factor of ∼ 7), whereas the electron and proton heating efficiencies become comparable at β i ∼ 2 if T e /T i = 1, when both species start already relativistically hot. We find comparable heating efficiencies between the two species also in the limit of relativistic reconnection (σ w 1). Our results have important implications for the two-temperature nature of collisionless accretion flows, and may provide the sub-grid physics needed in general relativistic MHD simulations.

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Section: Dependence Of Inflow and Outflow Velocity On β Isupporting

confidence: 92%

Section: Dependence Of Inflow and Outflow Velocity On β Imentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Electron and Proton Heating in Transrelativistic Magnetic Reconnection

Rowan

Sironi

Narayan

2017

ApJ

130

134

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“…These features are characteristic of the nongyrotropic electron distribution in the diffusion region. These triangular shapes and discrete striation in the distribution functions in the EDR have been shown to rotate toward the outflow direction in the PIC simulations (Bessho et al, 2014;Bourdin, 2017;Le et al, 2016;Shuster et al, 2015). To reconstruct the spatial distribution of these specific distribution The plots of cuts in the velocity spectra, Figures (2a-2g), show clear changes in their properties.…”

Section: Change In the Electron Distribution Functionmentioning

confidence: 94%

Structure of the Current Sheet in the 11 July 2017 Electron Diffusion Region Event

et al. 2019

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The structure of the current sheet along the Magnetospheric Multiscale (MMS) orbit is examined during the 11 July 2017 Electron Diffusion Region (EDR) event. The location of MMS relative to the X‐line is deduced and used to obtain the spatial changes in the electron parameters. The electron velocity gradient values are used to estimate the reconnection electric field sustained by nongyrotropic pressure. It is shown that the observations are consistent with theoretical expectations for an inner EDR in 2‐D reconnection. That is, the magnetic field gradient scale, where the electric field due to electron nongyrotropic pressure dominates, is comparable to the gyroscale of the thermal electrons at the edge of the inner EDR. Our approximation of the MMS observations using a steady state, quasi‐2‐D, tailward retreating X‐line was valid only for about 1.4 s. This suggests that the inner EDR is localized; that is, electron outflow jet braking takes place within an ion inertia scale from the X‐line. The existence of multiple events or current sheet processes outside the EDR may play an important role in the geometry of reconnection in the near‐Earth magnetotail.

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“…Ions are known to be heated widely within the ion outflow jets [5]. Electrons are also heated near the electron diffusion region (EDR), where the energy dissipation term in the electron rest frame J • E 0 ¼ J • ðE þ U e × BÞ is positive [6,7]. Here J, U e , E, and B are the current density, electron bulk velocity, and electric and magnetic fields, respectively.…”

mentioning

confidence: 99%

Disturbance of the Front Region of Magnetic Reconnection Outflow Jets due to the Lower-Hybrid Drift Instability

et al. 2019

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A 3D fully kinetic simulation shows that the lower-hybrid drift instability disturbs the front of magnetic reconnection outflow jets and additionally causes energy dissipation. The result is very consistent with a disturbance observed at the dipolarization front (DF) in Earth's magnetotail by the Magnetospheric Multiscale (MMS) mission. A fully kinetic dispersion relation solver, validated by the MMS observations, further predicts that the disturbance of the reconnection jet front could occur over different parameter regimes in space plasmas including Earth's DF and solar flares.

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Two-stage bulk electron heating in the diffusion region of anti-parallel symmetric reconnection

Cited by 21 publications

References 36 publications

Electron and Proton Heating in Transrelativistic Magnetic Reconnection

Electron and Proton Heating in Transrelativistic Magnetic Reconnection

Structure of the Current Sheet in the 11 July 2017 Electron Diffusion Region Event

Disturbance of the Front Region of Magnetic Reconnection Outflow Jets due to the Lower-Hybrid Drift Instability

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