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Matter and Electromagnetic Fields in Strong Gravity
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Matter and Electromagnetic Fields in Strong Gravity
CSIC Building (#406),
Seminar Room 4122.
Directions: home.cscamm.umd.edu/directions
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Global Simulations of Black Hole Accretion
John Hawley
University of Virginia
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Abstract:
Numerical simulations provide a way to investigate the
dynamics of accretion flows directly with far fewer limitations
compared to analytic models. Because magnetic fields are fundamentally
important for jets and disks, and because we now know that magnetic
turbulence accounts for the internal stress, the governing equations
are those of compressible magnetohydrodynamics (MHD). Accretion disk
dynamics can thus be investigated using three-dimensional MHD
simulation codes that employ both global and local computational
domains. Although it is not yet possible to do fully global time
dependent radiation transport in disk models, the observational
implications of these simulations can be investigated using simple
emission and absorption models coupled with relativistic ray
tracing. The time and length-scales involved make such simulations
challenging, but even the first results are intriguing. They have
revealed details about time-dependent properties of disks, magnetic
disk dynamos, jet launching mechanisms, and the dynamical properties
of systems other than the standard thin disk. As the capabilities of
computational hardware increase, and the development of advanced
numerical codes continues, our theoretical understanding of accretion
physics will substantially increase.
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