Theoretical Studies of Astronomical Masers

This proposal requests continuation of support for a broad, ongoing program of theoretical studies of astronomical masers. Recent maser interferometric observations reveal in unprecedented detail the structure of various astronomical environments. Seizing the opportunities created by this progress, the topics targeted for research include (1) proto stellar disks and outftows in high-mass star formation, as probed by methanol, water and SiO masers; (2) the circumstellar shells of evolved stars, traced by a variety of maser and thermal species; and (3) structure at the parsec and sub-parsec scales at the centers of starburst galaxies and active galactic nuclei as revealed by their OH and H2O megamaser emission. In each case, a major ingredient of the proposed research is the close collaboration with the observing teams conducting the pertinent observations. In addition to advancing knowledge and understanding within the different fields of studies, a major accomplishment of this program has been its continuing educational impact. Every graduate student trained under this program who has received his/her degree over the past fifteen years continues to maintain an active collaboration with it.