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Please use this identifier to cite or link to this item: http://arks.princeton.edu/ark:/88435/dsp01xw42nc296
Title: Small-Scale Dynamics of Dust in the Interstellar Medium
Authors: Moseley, Eric Roger
Advisors: Teyssier, Romain
Contributors: Astrophysical Sciences Department
Keywords: dust
interstellar medium
magnetohydrodynamics
numerical methods
particle kinetics
turbulence
Subjects: Astrophysics
Plasma physics
Issue Date: 2024
Publisher: Princeton, NJ : Princeton University
Abstract: The interstellar medium is replete with microscopic, sub-micron-sized dust grains. These grains obscure and adulterate a wide variety of astrophysical observations. Thus, understanding their properties is critical for understanding essentially all astrophysical objects. Furthermore, this same dust is what eventually coalesces into planetesimals, and eventually planets. Historically however, dust is most often assumed to be perfectly coupled to gas in the interstellar medium. In order to understand the dynamics of marginally coupled dusty interstellar plasma, we have implemented novel magnetohydrodynamic(MHD)-particle-in-cell(PIC) methods into the astrophysical fluid code RAMSES. We treat dust grains as a set of massive ``superparticles'' that experience aerodynamic drag and Lorentz force. We subject our code to a range of numerical tests designed to validate our method in different physical conditions, as well as to illustrate possible mechanisms by which grains can be accelerated. Having demonstrated the accuracy and stability of our MHD-PIC implementation, we turn our attention to understanding the velocity distributions of charged dust grains in generic conditions. We obtain a simple power-law relationship that quantifies the root-mean-square dust velocities as a function of the properties of the turbulence. Finally, we present the results of a high-resolution driven MHD turbulence simulation meant to represent as accurately as possible a small, parsec sized patch of cold neutral medium in order to understand dust-to-gas mass ratio fluctuations in this environment. We find that the dust density is roughly proportional to the square root of the gas density, with variations of factors of around 3 about this line. This work has wide-reaching implications, ranging from models for grain growth and destruction to the distribution of stellar metallicities.
URI: http://arks.princeton.edu/ark:/88435/dsp01xw42nc296
Type of Material: Academic dissertations (Ph.D.)
Language: en
Appears in Collections:Astrophysical Sciences

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