Theoretical astrophysics and plasma physics at RPC

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Relativistic non-thermal particle acceleration in two-dimensional collisionless magnetic reconnection

Journal of Plasma Physics Cambridge University Press (CUP) 88:1 (2022) 905880114

Abstract:

Magnetic reconnection, especially in the relativistic regime, provides an efficient mechanism for accelerating relativistic particles and thus offers an attractive physical explanation for non-thermal high-energy emission from various astrophysical sources. I present a simple analytical model that elucidates key physical processes responsible for reconnection-driven relativistic non-thermal particle acceleration in the large-system, plasmoid-dominated regime in two dimensions. The model aims to explain the numerically observed dependencies of the power-law index $p$ and high-energy cutoff $\gamma _c$ of the resulting non-thermal particle energy spectrum $f(\gamma )$ on the ambient plasma magnetization $\sigma$ , and (for $\gamma _c$ ) on the system size $L$ . In this self-similar model, energetic particles are continuously accelerated by the out-of-plane reconnection electric field $E_{\rm rec}$ until they become magnetized by the reconnected magnetic field and eventually trapped in plasmoids large enough to confine them. The model also includes diffusive Fermi acceleration by particle bouncing off rapidly moving plasmoids. I argue that the balance between electric acceleration and magnetization controls the power-law index, while trapping in plasmoids governs the cutoff, thus tying the particle energy spectrum to the plasmoid distribution.
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Modelling the stellar halo with RR-Lyrae stars

Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) 510:4 (2022) 4706-4722

Authors:

Chengdong Li, James Binney
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Interpreting Radial Correlation Doppler Reflectometry using Gyrokinetic Simulations

(2022)

Authors:

J Ruiz Ruiz, FI Parra, VH Hall-Chen, N Christen, M Barnes, J Candy, J Garcia, C Giroud, W Guttenfelder, JC Hillesheim, C Holland, NT Howard, Y Ren, AE White, JET contributors.
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A novel approach to radially global gyrokinetic simulation using the flux-tube code $\texttt{stella}$

(2022)

Authors:

DA St-Onge, M Barnes, FI Parra
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Insensitivity of a turbulent laser-plasma dynamo to initial conditions

(2022)

Authors:

AFA Bott, L Chen, P Tzeferacos, CAJ Palmer, AR Bell, R Bingham, A Birkel, DH Froula, J Katz, MW Kunz, C-K Li, H-S Park, R Petrasso, JS Ross, B Reville, D Ryu, FH Séguin, TG White, AA Schekochihin, DQ Lamb, G Gregori
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