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Measuring Magnetic Fields Near and Far via the Zeeman Effect

Physics/Astro Auditorium

Tim Robishaw (DRAO)

December 14 @ 4:00 PM - 5:00 PM

The Zeeman effect is the only observational tool that allows us to directly measure the magnetic field strength and direction in the interstellar medium.  We provide an overview of ongoing projects in which we are using Zeeman splitting of the 21-cm hydrogen line and the 18-cm hydroxyl (OH) transitions in order to probe astrophysical magnetic fields.  We will highlight the first detection of extragalactic Zeeman splitting in the OH megamaser emission from starburst galaxies.  Results will be shown from a survey of Zeeman splitting of OH masers in our Milky Way’s spiral arms that show large-scale field directions conflicting with those probed by Faraday rotation.  We will also discuss previous measurements of the Zeeman effect in Galactic 21-cm radio emission, some of the instrumental challenges involved in such measurements, and plans for a large-scale survey using the 26-m John A. Galt Telescope at the Dominion Radio Astrophysical Observatory.