Events at Physics
Events on Thursday, October 8th, 2020
- Cosmology Journal Club
- Time: 12:00 pm
- Abstract: Cosmology Journal Club is back! We will be having virtual meetings this semester.
Each week, we start with a couple scheduled 15 minute talks about one's research, or an arXiv paper. The last 30 minutes will typically be open to the group for anyone to discuss an arXiv paper.
All are welcome and all fields of cosmology are appropriate.
Contact Ross Cawthon, cawthon@wisc, for more information.
Meeting ID: 93592708053, passcode: cmbadger
- Astronomy Colloquium
- "Particle acceleration by pressure anisotropy plasma instabilities: from black hole accretion disks to solar flares."
- 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.
Meeting ID: 885 1389 6776
- Host: Professor Ellen Zweibel