Professor James Rossmanith; Department of Mathematics; Iowa State University

"An Overview of the Moment-Closure Problem for Kinetic Boltzmann Equations"

Abstract: In many applications, the dynamics of gas and plasma can be accurately modeled using kinetic Boltzmann equations. These equations are integro-differential systems posed in a high-dimensional phase space, which is typically comprised of the spatial coordinates and the velocity coordinates. If the system is sufficiently collisional the kinetic equations may be replaced by a fluid approximation that is posed in physical space (i.e., a lower dimensional space than the full phase space). The precise form of the fluid approximation depends on the choice of the moment-closure. In general, finding a suitable robust moment-closure is still an open scientific problem. In this talk I will give an overview of the moment-closure problem and describe various attempts at finding suitable closures the current generation of gamma-ray observatories.