Colloquium
Tiny
Galaxies and the Dark Matter Problem
Dr. Matthew Walker
Institute for Astronomy
University of Cambridge
Thursday, February 21, 2008, 1:40 p.m., SCIC 126
In a Universe that grows its galactic structure via
mergers, the smallest galaxies are the raw materials. The dwarf galaxies
that orbit the Milky Way are the smallest and faintest galaxies known, and
likely are the surviving members of the population of primordial galaxies
that merged to build the Milky Way. The internal motions of their stars
suggest that dwarf galaxies are composed almost entirely of dark matter. As
they are the smallest and most pristine examples we have found, dwarf
galaxies have much to tell us about the nature of dark matter.
I will summarize recent work in which I use the best available kinematic data to constrain the dark matter content of
dwarf galaxies. I will show that these systems have a characteristic mass
of ten million times that of the Sun, nearly all of which consists of dark
matter. I will discuss what these results can and cannot tell us about dark
matter, and how this work fits into the framework of modern cosmology.
Finally, I will discuss prospects for discovering new dwarf galaxies in the
Milky Way neighborhood.
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