Markov Chain Monte Carlo Modeling of the Tidal Stream of NGC 5466
Stephen Pardy, University of Wisconsin Madison
Advisors: Andreas Kupper
Abstract:
The Milky Way's dark matter halo remains poorly understood even in the
era of high precision cosmology. Tidal streams have the
unique ability to probe the potential field in the outer
regions of a galaxy where the dark matter halo
dominates. Although globular clusters are quite common, only
a few have definite tidal tails that make them good
candidates for measure the potential. In this paper we
present new models for NGC 5466, a cluster with a tentative
45 degree tidal tail, using recently acquired radial velocity and
proper motion data from bright stars in the stream. We model
the tidal stream of NGC 5466 using the streakline code
(Kupper et al. 2012) and an MCMC technique to efficiently
search over a large number of models. We compare models
constructed using the data of (Grillmair & Johnson 2006)
with those from (Belokurov et al. 2006). Our best models
constrain the Milky Way flattening parameter to be nearly 1,
indicating a spherical halo, while providing new, tighter
constraints for the proper motion of the cluster.
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