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Unformatted text preview: Faraday Rotation in the Interstellar Medium Paul Thorman Jr. Department of Physics University of Cincinnati Cincinnati, Ohio 45221 11/14/2001 Abstract Although wavelength and intensity of radiation are the most frequently used mea- sures in astrophysics, some distant sources of light also have polarization properties that can be used to learn about their constitution. This polarized light is also affected by the interstellar medium, which can be treated as a rarefied electron gas, and the effect of the medium is dependent on the presence and intensity of magnetic fields, as well as upon the density of the medium itself. The presence of magnetic fields is indicated by Faraday rotation, a change in the polarization plane of a signal as it passes through a medium in the presence of a magnetic field. These measurements can easily be applied to determine the gross magnetic field of our galaxy. 1 The light from a majority of stellar sources is not polarized to any measurable degree. There are a few exceptions: light from ”reddened stars,” which has been scattered by grains of dust, often shows signs of polarization due to such scattering, and pulsar light, while not constant in its polarization, can be averaged over a sample of perhaps 100 pulses to give a stable mean polarization . Pulsar light has the added advantage that each pulse containsstable mean polarization ....
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This note was uploaded on 01/08/2012 for the course PHYSICS 707 taught by Professor Electrodynamics during the Fall '11 term at LSU.
- Fall '11