We regret that this talk has been cancelled due to the snowstorm on the east coast.

James Stone, Professor of Astrophysical Sciences at Princeton University, will speak on campus as part of the Michigan Institute for Computational Discovery and Engineering (MICDE) Seminar Series.

Title: Global Radiation MHD Simulations of Black Hole Accretion Disks

Time/Date/Location: CANCELLED

Abstract: New results from a study of the magnetohydrodynamics of luminous accretion flows around black holes will be presented. In this regime, radiation pressure dominates the flow, thus the calculations require numerical methods based on a formal solution of the time-dependent radiation transfer equation. In this talk Prof. Stone will describe new algorithms he has developed that eliminate the need for approximate closures. He and his colleagues found that turbulent transport of radiation energy can be a significant contribution to the cooling rate in the disk, and this changes the global properties of the flow compared to standard thin-disk models. He will describe new work to extend the calculations to full general relativity, in order to follow the dynamics in the innermost regions of the disk.

Bio: James Stone is a Professor of Astrophysical Sciences at Princeton University. His research centers on the use of large-scale direct numerical simulations to study the gas dynamics of a wide range of astrophysical systems, from protostars to clusters of galaxies. Almost all of this work requires development of advanced numerical algorithms for astrophysical gas dynamics on modern parallel computer systems. He is one of the primary developers of the ZEUS code for astrophysical MHD, and more recently he and his collaborators developed Athena, a high-order Godunov scheme for astrophysical MHD that uses adaptive mesh refinement (AMR).

Some of the research problems on which he works include: (1) hydrodynamic and MHD processes that can lead to outward angular momentum transport in accretion disks, (2) the production and propagation of highly supersonic, collimated jets from accretion disks around protostars and active galactic nuclei, (3) the properties of compressible MHD turbulence in cold molecular gas in the galaxy, (4) the time-dependent evolution of strong shocks in the interstellar medium, (5) the structure of radiatively driven winds and outflows from disks around hot stars and AGN, and (6) the effect of mergers and AGN feedback on the hot x-ray emitting gas in clusters of galaxies.

Prof. Stone has a joint appointment in the Program in Applied and Computation Mathematics (PACM). He is deeply involved in PICSciE, which provides access to high-performance computing systems on Princeton’s campus, and training and education in scientific computation and numerical analysis.