University of Illinois Urbana-Champaign

The transfer of polarized radiation in astrophysical masers in the presence of magnetic fields

Nedoluha, Gerald Ernst

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Description

Title
The transfer of polarized radiation in astrophysical masers in the presence of magnetic fields
Author(s)
Nedoluha, Gerald Ernst
Issue Date
1990
Doctoral Committee Chair(s)
Watson, W.D.
Department of Study
Physics
Discipline
Physics
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
  • polarized radiation
  • astrophysical masers
  • star formation
  • circumstellar environments
Language
en
Abstract
"Polarized emission from astrophysical masers can provide important information about physical conditions in both star forming and circumstellar environments. Calculations are performed which give the spectra of the emergent maser radiation for different magnetic fields, radiative intensities, decay rates, and pumping rates thought to be appropriate in astrophysical masing regions. Results are obtained which for the first time make it possible to study the linear polarization of radiatively saturated masers when the stimulated emission rate and the Zeeman frequency are comparable, a regime which is of importance for nonparamagnetic masing molecules (i.e. H20, SiO, CH30H, H2CO) in astrophysics. The change in both the amount of linear polarization and its position angle as a function of the stimulated emission rate is followed through this regime. A striking feature of maser emission from OH molecules is the tendency for one of the circular polarizations to dominate the emission spectrum. The two mechanisms which may explain these observations both involve a masing gas in a velocity gradient These mechanisms are studied by calculating the emergent spectra of the radiation without making the ""large velocity gradient"" approximation which has always been made in previous calculations of masing in a velocity gradient. Eliminating this approximation leads to previously unsuspected narrow line profiles even in regions where large velocity gradients are present, as well as to polarized spectra that resemble those of the observations."
Type of Resource
text
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http://hdl.handle.net/2142/25205
Copyright and License Information
1990 Gerald Ernst Nedoluha

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