TY - JOUR A1 - Bohdan, Artem A1 - Niemiec, Jacek A1 - Pohl, Martin A1 - Matsumoto, Yosuke A1 - Amano, Takanobu A1 - Hoshino, Masahiro T1 - Kinetic Simulations of Nonrelativistic Perpendicular Shocks of Young Supernova Remnants. II. Influence of Shock-surfing Acceleration on Downstream Electron Spectra JF - The astrophysical journal : an international review of spectroscopy and astronomical physics N2 - We explore electron preacceleration at high-Mach-number nonrelativistic perpendicular shocks at, e.g., young supernova remnants, which are a prerequisite of further acceleration to very high energies via diffusive shock acceleration. Using fully kinetic particle-in-cell simulations of shocks and electron dynamics in them, we investigate the influence of shock-surfing acceleration (SSA) at the shock foot on the nonthermal population of electrons downstream of the shock. The SSA is followed by further energization at the shock ramp where the Weibel instability spawns a type of second-order Fermi acceleration. The combination of these two processes leads to the formation of a nonthermal electron population, but the importance of SSA becomes smaller for larger ion-to-electron mass ratios in the simulation. We discuss the resulting electron spectra and the relevance of our results to the physics of systems with real ion-to-electron mass ratios and fully three-dimensional behavior. KW - Shocks KW - Space plasmas KW - Supernova remnants KW - Interstellar medium Y1 - 2019 U6 - https://doi.org/10.3847/1538-4357/ab43cf SN - 0004-637X SN - 1538-4357 VL - 885 IS - 1 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Bykov, Andrei A1 - Gehrels, Neil A1 - Krawczynski, Henric A1 - Lemoine, Martin A1 - Pelletier, Guy A1 - Pohl, Martin T1 - Particle acceleration in relativistic outflows JF - Space science reviews N2 - In this review we confront the current theoretical understanding of particle acceleration at relativistic outflows with recent observational results on various source classes thought to involve such outflows, e.g. gamma-ray bursts, active galactic nuclei, and pulsar wind nebulae. We highlight the possible contributions of these sources to ultra-high-energy cosmic rays. KW - Cosmic rays KW - Particle acceleration KW - Shocks Y1 - 2012 U6 - https://doi.org/10.1007/s11214-012-9896-y SN - 0038-6308 VL - 173 IS - 1-4 SP - 309 EP - 339 PB - Springer CY - Dordrecht ER -