An Observational Study of Magnetic Fields in the Galaxy and Beyond

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The principal objective of Dr. Troland's research is to measure magnetic field strengths in many interstellar environments and to use this information to better understand the role of magnetic fields in our Galaxy and in others. It has long been known that interstellar material is permeated by weak magnetic fields. It is also known that these fields can play an important role in the dynamics and evolution of interstellar material, including the process of star formation. What is not well known is the strength of the field in a wide variety of interstellar environments. A detailed knowledge of field strengths is important. The effects of these fields on interstellar clouds depend crucially upon the ratio of magnetic energies to other relevant energies in the clouds. The relationship between increasing field strength and increasing gas density can reveal much about the details of the contraction process. On the galactic scale, magnetic field strengths may be closely related to the overall rate at which new stars form in a galaxy.Dr. Troland seeks to expand upon previous observations of the radio frequencyZeeman effect, the only known technique for measuring magnetic field strengths inlocalized regions of interstellar material. The recent upgrade of the Arecibo 300 meter radio telescope and the impending completion of the 100m Green Bank Telescope offermany new opportunities to study interstellar magnetic field strengths. In this project, theZeeman effect will be studied in spectral lines of a variety of interstellar species includingHI, OH (ground and excited states), CCS, C4H, CH and H2O. This project shouldprovide a significant increase in our knowledge of magnetic fields in a wide variety ofgalactic interstellar environments. This project may also provide the first directmeasurements of magnetic fields in galaxies beyond our own.