Dynamics of Dust in Plasma and Implications to CMB and Magnetic Fields Studies

Type Conference Paper
Names Thiem Hoang
Proceedings Title Bulletin of the American Astronomical Society
Conference Name American Astronomical Society, AAS Meeting #219, #440.10
Volume 219
Date January 1, 2012
URL http://adsabs.harvard.edu/abs/2012AAS...21944010H
Library Catalog NASA ADS
Abstract Dust is a ubiquitous constituent of the interstellar medium, molecular clouds, and circumstellar and protoplanetary disks. Dust emission interferes with observations of cosmic microwave background (CMB) temperature anisotropy and its polarized emission dominates the CMB B-mode polarization that prevents us from getting insight into the inflation epoch of the early universe. We study fundamental physical processes of dust dynamics in plasma and explore their implications to observations of the CMB, studies of magnetic fields, and formation of planets. We quantified spinning dust emission (SDE) from wobbling small grains with non-spherical shapes. We investigated the effects of transient heating by UV photon and compressible turbulence on SDE. This improved SDE model reproduces very well observation data by Wilkinson Microwave Anisotropy Probe and allows a reliable subtraction of Galactic contamination from the CMB. We identified grain helicity as the major driver for grain alignment via radiative torques (RATs) and suggested an analytical model of RATs based on this concept. Dust polarization predicted by the model has been confirmed by numerous observations, and can be used as a frequency template for the CMB B-mode searches. We proposed a new type of dust acceleration due to magnetohydrodynamic turbulence through transit time damping for large grains and quantified a novel acceleration mechanism induced by charge fluctuations for very small grains using Monte Carlo simulations. Grain velocities from these new acceleration mechanisms are necessary for understanding dust coagulation in protoplanetary disks and formations of planets.
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