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A Clash of Clusters Provides New Clue to Dark Matter
Special ACKS Seminar: Dragan Huterer
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Cosmology Seminar: Beth Willman (CfA/Harvard)
| What | seminar cosmology |
|---|---|
| When |
07 April 08 from 11:00 am to 12:00 pm |
| Where | Varian Room 355 |
| Contact Name | Laura Duato |
| Contact Email | lduato@stanford.edu |
| Add event to calendar |
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The Least Luminous Galaxies: learning to love the CMD and stop worrying about CDM
Since 2005, nearly 20 dwarf galaxies have been discovered around the
Milky Way and M31 that have up to 100 times fewer stars than any
galaxy previously known. A robust census, plus kinematic and
abundance studies of these least luminous galaxies are proving
critical to our understanding of the abundance, spatial, and mass
distribution of dark matter on small scales. Finding these objects
relies on identifying slight overdensities of stars occupying a
well-defined region of the color-magnitude diagram. In this talk, I
present some successes and limitations of searches for the least
luminous galaxies and take a critical look at our present knowledge of
the true population of dwarfs around the Milky Way. I discuss the
properties of the new Milky Way dwarfs as a population, including
possible evidence for tidal disturbance and the spectroscopic
observations that appear to confirm their residence within dark matter
halos. I also examine in detail the properties of three objects with
only 1000 solar luminosities (Willman 1, Bootes II, Segue 1) to assess
whether we can yet functionally distinguish star clusters from dwarf
galaxies at the extremely low luminosities at which future surveys may
reveal an abundance of objects. I end by discussing the implications
of the recently discovered Milky Way dwarf galaxies in a Cold Dark
Matter plus galaxy formation context, including resolutions to the
so-called 'Missing Satellites Problem'.
MASS: Lance Simms