Simulating Black Hole Accretion in Unexplored Regimes

Matthew Liska (Amsterdam) - November 19, 2018 at 12:10 pm

Abstract: Due to a large scale separation in space and time, black hole accretion systems are challenging to study numerically. When the disk is geometrically thin and tilted with respect to the spinning black hole, as expected for luminous quasars, the challenge becomes extreme. To make such simulations possible, I developed an adaptive mesh general relativistic MHD code H-AMR, which is accelerated by graphical processing units (GPUs). I will start by discussing how accretion disks respond to the tilt depending on their thickness. In particular, I will demonstrate for the first time that tilted disks can produce precessing relativistic jets. I will then show that thin disks, when tilted, can undergo alignment with the black hole midplane, resolving a 40-year long puzzle of whether such alignment is possible. Interestingly, such disks can also break into independently precessing segments, an effect seen in turbulent disks for the first time that has the potential to dramatically change the observational appearance of black hole accretion. I will finish by discussing the necessary ingredients for jet formation, such as disk thickness and the geometry of seed magnetic field.

The seminar will be held in 131A Campbell Hall.

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