Date of Award

2000

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

First Advisor

Geoffrey C. Clayton

Abstract

In the first part of this thesis, the ultraviolet extinction from dust in the Large Magellanic Cloud is re-analyzed. Differences in the extinction properties between different lines of sight, as well as between the LMC, SMC, and Milky Way are discussed in the context of their implications for the constitution and size distributions of the dust grains. The UV extinction curves derived in this work, along with those from other studies, have been used to constrain dust models used as inputs to dust heating models. Next, the DIRTY model, a Monte Carlo radiative transfer code from the ultraviolet to the far IR, is extended to self-consistently include dust heating and emission, fully accounting for the effects of the transient heating of small grains. The code is completely general; the density structure of the dust, heating sources, and their geometric configurations can be specified arbitrarily. The dust scattering, absorbing, and emitting properties are calculated from realistic dust models derived by fitting observed extinction curves. Dust self-absorption is also accounted for by treating photons emitted by the dust as an additional heating source and adopting an iterative radiative transfer scheme. The dependence of the UV-FIR SED, dust temperatures, and dust masses predicted by DIRTY on variations of the input parameters is examined. Finally, the DIRTY model is applied directly to a sample of nearby starburst galaxies. The UV to far IR SEDs of the galaxies are well reproduced using DIRTY, and quantitative information including star formation rates, dust masses, and dust temperatures are derived. The ability to accurately reproduce the full SED of starburst galaxies is discussed in the context of modeling galaxies at high redshift. The model developed in this thesis is well suited to simulate galaxies at different evolutionary stages and hence has promise for investigating the star formation history of the universe. However, it must be emphasized that its range of applicability is not limited to galaxies. It should prove a useful tool in future investigations of a wide range of astrophysical systems in which dust plays an important role.

ISBN

9780599906136

Pages

141

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