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Polarization Properties of Astrophysical Masers


Kwan, John Ying-Kuen (1973) Polarization Properties of Astrophysical Masers. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/906J-2N21.


Observed interstellar OH and H2O maser lines at 18 cm and 1.35 cm exhibit unusual polarization properties. The OH emitters with the highest brightness temperatures, usually associated with H II regions, almost always show a high degree of circular polarization. The H2O maser line, on the other hand, is rarely polarized, and then only linearly polarized.

The preference for circular polarization in the brightest OH sources was attributed by Litvak to the mechanism of parametric down-conversion. In this process the higher-frequency components of a Zeeman split maser line are down-converted to lower-frequency components and to an electron cyclotron wave. This mechanism is shown to be too weak to be of importance in astrophysical masers.

The polarization properties of the OH and H2O masers are related to the physical conditions in the maser clouds. It is found that the magnetic field, the plasma, and trapped infrared lines in maser sources play an important role in determining the polarization on the emitted radiation.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Physics
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Physics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Goldreich, Peter Martin
Group:TAPIR, Astronomy Department
Thesis Committee:
  • Unknown, Unknown
Defense Date:20 November 1972
Funding AgencyGrant Number
Earle C. Anthony FoundationUNSPECIFIED
Record Number:CaltechTHESIS:08252017-145131867
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:10392
Deposited By: Benjamin Perez
Deposited On:25 Aug 2017 22:20
Last Modified:10 Mar 2020 19:16

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