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Activity Number: 93
Type: Invited
Date/Time: Monday, August 3, 2009 : 8:30 AM to 10:20 AM
Sponsor: IMS
Abstract - #302836
Title: Detecting Streaming Motion in Dwarf Spheroidal Galaxies Using Threshold Models
Author(s): Bodhisattva Sen*+
Companies: Columbia University
Address: 1032 SSW, New York, NY, 10027,
Keywords: asymptotic theory ; change-point models ; isotonic regression ; model mis-specification ; resampling methods ; split-point estimators
Abstract:

Whether a dwarf spheroidal galaxy is in equilibrium or being tidally disrupted by the Milky Way is an important question for the study of its dark matter content and distribution. This question is investigated using observations from the dwarf spheroidal Leo I [published in Mario, Olszewski, and Walker (2008)]. For Leo I, tidal disruption is detected, at least for stars sufficiently far from the center, but the effect appears to be quite modest. One can expect the streaming effects to only begin to appear outside a "tidal radius." We propose threshold/change-point models to estimate this tidal radius. We investigate both parametric and nonparametric (mis)-specified models for estimating the threshold.

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