Physics and Astronomy Colloquium - Dr. Omer Blaes, University of California Santa Barbara
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Title: Magnetohydrodynamics and Convection in Accretion Disks: From Dwarf Novae to Luminous Quasars
One of the most powerful sources of energy in the universe is the liberation of gravitational binding energy as plasma falls into a central object, such as a black hole. Such accretion flows are dynamically complex, involving significant rotational support against gravity, transport of angular momentum by magnetic turbulence, and turbulent dissipation. Unfortunately, simulations of these processes have had a checkered history of explaining observed accretion powered sources in the universe. In this talk, I will show how an additional complicating factor, opacity-driven convection, exerts a powerful back reaction on the dynamics of these flows, and might provide an explanation for a variety of observed phenomenology in luminous accretion flows around white dwarfs and supermassive black holes.
After spending his formative years growing up in the UK, Omer Blaes earned his doctorate at the International School for Advanced Studies (SISSA) in Trieste, Italy. He then did postdoctoral work at the California Institute of Technology and the Canadian Institute of Theoretical Astrophysics in Toronto. He finally joined the Physics Department faculty at the University of California, Santa Barbara in 1993 and has been there ever since. He has worked on a variety of problems in theoretical high energy astrophysics, particularly on the theory of so-called accretion disks: rapidly rotating flows around black holes and other compact objects that liberate gravitational energy into energetic outflows and radiation that we observe in a variety of spectacular phenomena across the universe.