Dark Matter and the Dynamics of Galaxies

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AST-0098282Sellwood, Jerry A.Over the past two decades astronomers have amassed a considerable body of evidence for the existence of an unseen component of the universe which exerts a gravitational-like influence but has no other identified signature. This component is known as "dark matter." Our imperfect knowledge of the content and distribution of dark matter in galaxies is a major obstacle to our current understanding of the structure and formation of galaxies. This project has three parts all of which are designed to measure the dark matter content of different galaxies. Two of these research projects will attempt to quantify the amount of dark matter in spiral galaxies and the third will search for a possible systematic difference between the dark matter content of barred galaxies and of their unbarred counterparts. These projects involve numerical computer computations of galaxy models taking into account both gravitationally induced "particle" motion as well as adiabatic compression of dark matter halos as gas cools and settles into pre-existing potential wells. One final result of this program is the elaboration of a mechanism for the origin of bars in galaxies, a topic which has been given renewed urgency by recent observational and theoretical developments. Funding for this project was provided by the NSF program for Extragalactic Astronomy & Cosmology (AST/EXC).***