Relativistic resistive magnetohydrodynamic reconnection and plasmoid formation in merging flux tubes
| Autor: | Bart Ripperda, Rony Keppens, Lorenzo Sironi, Oliver Porth |
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| Přispěvatelé: | High Energy Astrophys. & Astropart. Phys (API, FNWI) |
| Jazyk: | angličtina |
| Rok vydání: | 2019 |
| Předmět: |
ACCRETION FLOW
MHD black hole physics SWEET-PARKER FOS: Physical sciences Plasmoid Astronomy & Astrophysics 01 natural sciences Instability TEARING INSTABILITY Magnetization Current sheet Electrical resistivity and conductivity Physics::Plasma Physics MAGNETIC RECONNECTION 0103 physical sciences 010303 astronomy & astrophysics Physics High Energy Astrophysical Phenomena (astro-ph.HE) Science & Technology Condensed matter physics 010308 nuclear & particles physics Astronomy and Astrophysics Magnetic reconnection numerical [methods] FAST TEV VARIABILITY CURRENT SHEETS SUPERMASSIVE BLACK-HOLE Magnetic flux SIMULATIONS Space and Planetary Science Physics::Space Physics Physical Sciences FLARES X-RAY accretion accretion discs Magnetohydrodynamics Astrophysics - High Energy Astrophysical Phenomena |
| Zdroj: | Monthly Notices of the Royal Astronomical Society, 485(1), 299-314. Oxford University Press |
| ISSN: | 0035-8711 |
| Popis: | We apply the general relativistic resistive magnetohydrodynamics code {\tt BHAC} to perform a 2D study of the formation and evolution of a reconnection layer in between two merging magnetic flux tubes in Minkowski spacetime. Small-scale effects in the regime of low resistivity most relevant for dilute astrophysical plasmas are resolved with very high accuracy due to the extreme resolutions obtained with adaptive mesh refinement. Numerical convergence in the highly nonlinear plasmoid-dominated regime is confirmed for a sweep of resolutions. We employ both uniform resistivity and non-uniform resistivity based on the local, instantaneous current density. For uniform resistivity we find Sweet-Parker reconnection, from $\eta = 10^{-2}$ down to $\eta = 10^{-4}$, for a reference case of magnetisation $\sigma = 3.33$ and plasma-$\beta = 0.1$. {For uniform resistivity $\eta=5\times10^{-5}$ the tearing mode is recovered, resulting in the formation of secondary plasmoids. The plasmoid instability enhances the reconnection rate to $v_{\rm rec} \sim 0.03c$ compared to $v_{\rm rec} \sim 0.01c$ for $\eta=10^{-4}$.} For non-uniform resistivity with a base level $\eta_0 = 10^{-4}$ and an enhanced current-dependent resistivity in the current sheet, we find an increased reconnection rate of $v_{\rm rec} \sim 0.1c$. The influence of the magnetisation $\sigma$ and the plasma-$\beta$ is analysed for cases with uniform resistivity $\eta=5\times10^{-5}$ and $\eta=10^{-4}$ in a range $0.5 \leq \sigma \leq 10$ and $0.01 \leq \beta \leq 1$ in regimes that are applicable for black hole accretion disks and jets. The plasmoid instability is triggered for Lundquist numbers larger than a critical value of $S_{\rm c} \approx 8000$. Comment: Matching accepted version in MNRAS |
| Databáze: | OpenAIRE |
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