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Paper: Magnetic Fields in the Galactic Center
Volume: 186, The Central Parsecs of the Galaxy
Page: 483
Authors: Roberts, D. A.
Abstract: Early models of the magnetic field structure of the Galactic Center suggested very strong field strengths. In the past decade or so, there have been many projects to investigate the morphology and strength of the magnetic fields in the inner parsec of the Galactic Center. Magnetic field observations include primarily near and far-infrared polarization and Zeeman measurements. The infrared polarization measurements along with a model for the polarization mechanism provide the magnetic field morphology in the plane of the sky. The only direct quantitative measurement of the magnetic field strength in the Galactic Center is obtained from observing the Zeeman effect in radio frequency spectral lines. Centimeter-wavelength Zeeman observations of Sgr A have been carried out in several gas components: neutral hydrogen (HI), hydroxyl (OH), and hydrogen recombination lines (H92α). Line-of-sight fields have been measured at the level of a few milligauss. These fields are much stronger than those in the ambient interstellar medium (whose average is a few microgauss) and are similar to fields in the cores of dense molecular clouds. This talk will discuss new observations of the Zeeman effect in OH(1720MHz) line observed in a maser in the Circumnuclear disk (CND) and the correlation with the HI Zeeman measurements at the same location. New OH (1720MHz) Zeeman results are interpreted in the context of previous Zeeman and polarization observations.
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