The Dynamic and Mysterious Outskirts of Galaxies
Raja Guhathakurta

Three ongoing studies of the outer regions of galaxies will be discussed in this talk.

The first of these studies targets low-luminosity dwarf elliptical (dE) galaxies in the Virgo cluster for which we have data from the NGVS and SMAKCED surveys. Globular cluster satellites are used as dynamical tracers to measure the dark matter content of dEs. New results on mysterious kinematic anomalies will also be presented along with results on rotational versus pressure support in dEs.

The second study is of the structure, kinematics, and chemical enrichment of the outer stellar halo and disk of the Andromeda galaxy and its dwarf satellites. The latest results from the SPLASH and PHAT collaborations will be presented including the clumpy and dynamically hot stellar disk and unusual satellite internal dynamics.

The third study (HALO7D and HSTPROMO) is of the outer regions of the Milky Way - a study that started as a by-product of the above two studies. Topics will include kinematics of substructure in the outer halo, proper motion of stars from deep multi-epoch HST images, and a newly started deep Keck/DEIMOS spectroscopic survey to measure radial velocities and metallicities of Milky Way halo main sequence turnoff stars. By-products will include very high-quality spectra of distant star-forming and quiescent galaxies and M31 red giant stars.