Galaxy Formation and the Formation of the Galaxy

Julio F. Navarro
University of Victoria, Canada

The Cold Dark Matter paradigm of structure formation has proved
remarkably successful at accounting for the large-sale properties of the
Universe, as measured by the clustering and motions of galaxies, as well
as by the detailed structure of the temperature fluctuations in the
Cosmic Microwave Background. Some of its "natural" predictions regarding
the hierarchical assembly of galaxy systems, however, appear at odds
with observational data on the dynamics of individual galaxies and of 
the Milky Way. I will reevaluate the constraints that stellar dynamical 
data in the solar neighbourhood place on the Milky Way's formation 
history, and I will argue that the kinematics and chemical properties of 
nearby stars suggest that accretion and tidal disruption events have 
played an important role in the formation of both the spheroid and disk 
components of the Galaxy. Particularly interesting relicts of these 
events are the most massive globular cluster in the Galaxy, omega 
Centauri, and the third-brightest star in the northern night-sky, Arcturus.