TAPIR Seminar

Many astrophysical systems are magnetized and weakly collisional. As such, their mean, global properties are vastly separated in both space and time from the detailed kinetic microphysics that governs the transport of momentum, heat, and magnetic fields. Elucidating this physics is a vital step towards understanding why the intracluster medium avoids catastrophic cooling, how angular momentum is transported in radiatively inefficient accretion flows, and what shapes the observed distribution function in the solar wind. In this talk, I will present a unified description of these systems in terms of the pressure anisotropy, a directional bias in thermal pressure caused by adiabatic evolution in a magnetized plasma. Its impact on both micro- and macro-scales is examined using analytical theory and numerical simulations, the latter made possible by a new hybrid-kinetic particle-in-cell code, Pegasus (Kunz et al. 2013). Pioneering studies of collisionless magnetorotational turbulence and of fast-growing microscale instabilities will be placed within the larger context of formulating a pragmatic framework for modeling astrophysical multiscale plasma dynamics.