Title: A Subaru/Keck Survey of faint dwarfs and substructure in the halo of M31
Author(s):Michelle Collins, Scott Chapman, Mike Irwin
Abstract:
Hierarchical structure formation predicts that large galaxies are built up through the mergers of smaller galaxies. But several problems with this model of formation persist, such as reconciling the low number of satellites we observe with those predicted in simulations, and the ability of fragile stellar discs to survive the ``major mergers'' predicted. In order to better understand this complex formation process, we have turned our focus to the halo of M31 in order to catalogue its satellite population, and search for the remnants of previous mergers. In this contribution I will present results from 15 fields in the M31 halo targeting streamy substructure (such as the NE blob region) and a number of very faint dSphs (notably And XI, XII and XIII) that have been observed photometrically with Subaru, and spectroscopically with Keck, and discuss the implications for the evolutionary history of M31 and other spiral galaxies, including the MW.