Unique Approaches to Magnetic Phenomena: Polarized CMB Foregrounds and the Magnetorotational Instability

Susan Clark (Columbia University)

August 24, 2016

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Abstract: I will present unique approaches to two open problems in magnetized plasmas: the search for inflationary gravitational wave B-mode polarization in the CMB, and the saturation mechanism of the magnetorotational instability (MRI). B-mode detection would be the first direct evidence of inflation, but is currently limited by the Galactic polarized dust foreground. I will describe how magnetically aligned neutral hydrogen structures in the interstellar medium can constrain this foreground (Clark et al 2015, PRL). The second open problem I investigate deals with saturation, which is key to the MRI”s role as a driver of turbulence and angular momentum transport in accretion disks and stellar interiors, but remains poorly understood. I will describe an investigation of MRI saturation using weakly nonlinear analysis, a perturbative treatment of the instability near threshold (Clark & Oishi 2016, in prep).