Early acceleration of electrons and protons at the nonrelativistic quasiparallel shocks with different obliquity angles

Abstract

The early acceleration of protons and electrons in the nonrelativistic collisionless shocks with three obliquities are investigated through 1D particle-in-cell simulations. In the simulations, the charged particles possessing a velocity of $0.2c$ flow towards a reflecting boundary, and the shocks with a sonic Mach number of $13.4$ and a Alfven Mach number of $16.5$ in the downstream shock frame are generated. In these quasi-parallel shocks with the obliquity angles $\theta =15^{\circ }$, $30^{\circ }$, and $45^{\circ }$, some of the protons and the electrons can be injected into the acceleration processes, and their downstream spectra in the momentum space show a power law tail at a time of $1.89\times 10^5{\omega }_{\mathrm{pe}}^{-1}$, where ${\omega }_{\mathrm{pe}}$ is the electron plasma frequency. Moreover, the charged particles reflected at the shock excite magnetic waves upstream of the shock. The shock drift acceleration is more prominent with a larger obliquity angle for the shocks, but the accelerated particles diffuse parallel to the shock propagation direction more easily to participate in the diffusive shock acceleration. At the time still in the early acceleration stage, more energetic protons and electrons appear in the downstream of the shock for $\theta =15^{\circ }$ compared with the other two obliquities; moreover, in the upstream region, the spectrum of the accelerated electrons is the hardest for ${\theta }_{\mathrm{nB}}=45^{\circ }$ among the three obliquities, whereas the proton spectra for ${\theta }_{\mathrm{nB}}=15^{\circ }$ and $45^{\circ }$ are similar as a result of the competition of the effectiveness of the shock drift acceleration and the diffusive shock acceleration.

arXiv comment10 pages, 10 figures, accepted for publication in RAA

References in corpus (20)

• SMILEI: a collaborative, open-source, multi-purpose particle-in-cell code for plasma simulation
• Simulations of Ion Acceleration at Non-relativistic Shocks. I. Acceleration Efficiency
• Supernova remnants: the X-ray perspective
• The microphysics of collisionless shock waves
• Simulations of Ion Acceleration at Non-relativistic Shocks. II. Magnetic Field Amplification
• First detection of VHE gamma-rays from SN 1006 by H.E.S.S
• Non-Thermal Electron Acceleration in Low Mach Number Collisionless Shocks. I. Particle Energy Spectra and Acceleration Mechanism
• Non-Thermal Electron Acceleration in Low Mach Number Collisionless Shocks. II. Firehose-Mediated Fermi Acceleration and its Dependence on Pre-Shock Conditions
• Ion acceleration in non-relativistic astrophysical shocks
• Electron Injection at High Mach Number Quasi-Perpendicular Shocks : Surfing and Drift Acceleration
• Role of ejecta clumping and back-reaction of accelerated cosmic rays in the evolution of Type Ia supernova remnants
• Proton Acceleration in Weak Quasi-parallel Intracluster Shocks: Injection and Early Acceleration
• The Acceleration of Electrons at Collisionless Shocks Moving Through a Turbulent Magnetic Field
• Nonrelativistic parallel shocks in unmagnetized and weakly magnetized plasmas
• Ion Dynamics at A Rippled Quasi-parallel Shock: 2-D Hybrid Simulations
• Non-relativistic perpendicular shocks modeling young supernova remnants: nonstationary dynamics and particle acceleration at forward and reverse shocks
• Ion Acceleration at the Quasi-Parallel Bow Shock: Decoding the Signature of Injection
• Particle acceleration and wave excitation in quasi-parallel high-Mach-number collisionless shocks: Particle-in-cell simulation
• An explanation of the formation of the peculiar periphery of Tycho's supernova remnant
• An explanation for the peculiar periphery of supernova remnant G309.2-0.6

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