Formation and Evolution of Disks, Large and Small
Tom Quinn
University of Washington
November 9, 2009, 4PM, Steward N210
I will present two recent results from self-consistent N-body + smooth
particle hydrodynamics simulations of disk formation. In simulations
of isolated disks, we show that stars migrate across significant
galactocentric distances due to resonant scattering with transient
spiral arms, while preserving their circular orbits. Radial migration
provides an explanation for the observed flatness and spread in the
age-metallicity relation and the relative lack of metal-poor stars in
the solar neighborhood. The presence of radial migration also prompts
rethinking of interpretations of extragalactic stellar population
data, especially for determinations of star formation histories. In
simulations of dwarf galaxies formed by hierarchical merging, we show
that bulgeless dwarf galaxies with near constant density cores are a
natural outcome of galaxy formation in the CDM scenario. This is
achieved by resolving the inhomogeneous interstellar medium, resulting
in strong outflows from supernovae explosions which remove low angular
momentum gas. This inhibits the formation of bulges and decreases
the dark-matter density within the central kiloparsec.
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