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Astronomy Colloquium
"Particle acceleration by pressure anisotropy plasma instabilities: from black hole accretion disks to solar flares."
Date: Thursday, October 8th
Time: 3:30 pm
Place: Zoom meeting(see Abstract ) Coffee and tea 3:30pm, Talk 3:45pm
Speaker: Mario Riquelme, University of Chile
Abstract: Pressure anisotropies naturally arise in weakly collisional plasmas, and are ultimately limited by the pitch-angle scattering provided by various kinetic plasma instabilities. I will present particle-in-cell (PIC) plasma simulations of these instabilities, and will show that, in some regimes, their scattering can be highly inelastic and produce significant nonthermal particle acceleration. The presentation will focus on two astrophysical plasma environments: i) sub-relativistic, weakly collisional accretion disks around black holes (e.g., Sgr A*), where both electron and ion acceleration will be considered, and ii) non-relativistic, low beta plasmas relevant for solar flares, where the case of electron acceleration will be analyzed. I will review the main evidence for the existence of particle acceleration in these systems, and will discuss the importance that pressure anisotropy instabilities can have in helping explain these fascinating acceleration phenomena.

Zoom Information
https://us02web.zoom.us/j/88513896776?pwd=Y1JtRE1KZllxWkFTamJBSGtGdm9yQT09

Meeting ID: 885 1389 6776

Passcode: 713070
Host: Professor Ellen Zweibel
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