Although it is generally accepted that massive dark matter halos surround all large, bright galaxies, many of the basic properties of galaxy-sized dark matter halos remain poorly constrained. This project focuses on using small, faint satellite galaxies, orbiting within the gravitational potentials of large, bright field galaxies, to obtain a substantial improvement over the current halo constraints. The research will use a combination of theory, archival and new observations, and numerical datasets, to address a) the best halo virial mass estimator, b) how best to measure the velocity dispersion of satellite galaxies, c) the dependence of the mass-to-light ratio on luminosity, and whether this differs for early- and late-type galaxies, d) whether the halos of late-type galaxies are fundamentally different from those of early-type galaxies, and e) whether the angular momentum of a disk galaxy closely correlates with the net angular momentum of its halo.
The principal investigator will participate in Lowell Observatory's successful outreach program, targeting fifth through eighth grade students at Navajo and Hopi Nation Schools. This teacher-astronomer partnership is a significant commitment of time, including classroom visits, timed to coincide with observing runs, and an extended field trip for the students. The research will contribute to the professional development of a graduate student. All of the genuine and simulated data, and the software used, will be publicly available.
