We will also carry out polarimetric mapping towards the Galactic Center that will reveal the large-scale configuration of the magnetic field in the nucleus of the Galaxy. Within galaxies one finds many kinds of structures, including individual stars, clusters of stars, cloud complexes containing millions of solar masses of gas and dust, and the mysterious concentrations of matter that lie at the centers of galaxies. The formation of these structures involves the interaction of matter in a wide range of physical states, and involves gravitational forces, magnetic fields, and turbulence. The best way to map the distribution of dust is to observe its submillimeter-wave thermal emission, and one of the best ways to trace out magnetic field lines is via linear polarization measurements of this dust emission. Magnetic fields and dust are each believed to play important roles in the physical processes that result in the formation of structures in galaxies.
Magnetic fields are energetically important throughout most of the interstellar medium.
Ground-based submillimeter observations are hindered by atmopheric absorption due to water vapor. The recent establishment of an astronomical observing base at the South Pole, where the atmosphere is exceptionally dry, has now made such large-scale mapping possible. We are building a submillimeter detector system and will use it at the South Pole to carry out a submillimeter survey of the portion of the Galactic plane that is visible from this site. This will be the first large-scale submillimeter survey that has sufficient angular resolution to resolve individual molecular clouds throughout the Galaxy. It is in such clouds that stars form.