Göttingen 2025 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
P: Fachverband Plasmaphysik
P 15: Astrophysical Plasmas
P 15.4: Vortrag
Mittwoch, 2. April 2025, 17:00–17:15, ZHG102
Particle acceleration at oblique high-Mach-Number shocks propagating in a turbulent medium — •Eloise Moore1, Karol Fulat2, Michelle Tsirou3, and Martin Pohl1,3 — 1Institute of Physics and Astronomy, University of Potsdam, D-14476 Potsdam, Germany — 2Department of Astronomy, University of Wisconsin-Madison, Madison, WI 53706, USA — 3DESY, Platanenallee 6, 15738 Zeuthen, Germany
Astrophysical collisionless shocks are efficient particle accelerators, however, some pre-acceleration mechanism is needed for electrons to participate in diffusive shock acceleration. We investigate how pre-existing turbulence could modify the shock structure, plasma instabilities, and ultimately particle acceleration. The particle-in-cell (PIC) method provides a kinetic description of a system from first principles of collisionless plasma. Using the PIC code THATMPI, we performed novel simulations of oblique non-relativistic high-Mach-number shocks propagating into an upstream with pre-existing turbulence. We consider decaying compressive turbulence with density fluctuations of amplitude around 15%, consistent with measurements of the local interstellar medium. We find that the turbulence was able to modify the properties of the shock-reflected electrons that drive plasma instabilities ahead of the shock front. While we find that the energy spectrum of the downstream electrons shows a non-thermal tail for both homogeneous and turbulent simulated environments, the latter indicates more efficient electron acceleration. We conclude that the presence of turbulence plays a key role in the pre-acceleration mechanisms at play.
Keywords: Particle acceleration; Shocks; Instabilities