Northwestern Events Calendar

Sep
27
2016

Xuening Bai: The Microphysics of Astrophysics: Adventures in Computational Magnetohydrodynamics

When: Tuesday, September 27, 2016
4:00 PM - 5:00 PM CT

Where: Technological Institute, F160, 2145 Sheridan Road, Evanston, IL 60208 map it

Audience: Faculty/Staff - Student - Public - Post Docs/Docs - Graduate Students

Contact: Pamela Villalovoz   (847) 491-3644

Group: Physics and Astronomy Astrophysics Seminars

Category: Academic

Description:

Title: The Microphysics of Astrophysics: Adventures in Computational Magnetohydrodynamics


Speaker: Xuening Bai, Harvard-Smithonian Center for Astrophysics


Host: Sourav Chatterjee

Abstract: Astronomical observations yield rich data of phenomenology on macroscopic scales, while they are typically consequences of microphysical processes on much smaller scales. Many of such processes involve magnetic fields, instabilities and turbulence, and are the subject of computational magnetohydrodynamics (MHD). By properly incorporating the microphysics, I will draw three examples demonstrating that MHD simulations can greatly improve our understandings towards reality, and sometimes lead to surprises. First, I discuss how to build a “magnetically arrested disk” (MAD), characterized by having large amount of magnetic flux threading the central black hole, which has recently been realized to be able to launch powerful jets from AGNs and X-ray binaries. Second, I discuss the gas dynamics in protoplanetary disks (PPDs) and show that disk evolution is largely MHD-wind-driven, governed by the amount of magnetic flux threading the disk. I will further discuss magnetic flux evolution in PPDs. Finally, I describe an MHD-Particle-in-Cell method for coupling cosmic-rays with a thermal plasma, and discuss its applications to particle acceleration and cosmic-ray transport via cosmic-ray-driven instabilities.

 

Keywords: Physics, Astronomy, Astrophysics

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