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7 - Tutorial: Modeling tidal streams using N-body simulations

Published online by Cambridge University Press:  05 November 2013

By
J. Peñarrubia
Edited by
David Martínez-Delgado
J. Peñarrubia
Affiliation:
University of Cambridge
David Martínez-Delgado
Affiliation:
Max-Planck-Institut für Astronomie, Heidelberg
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Summary

7.1 Introduction: exercise goals

The main goal of this practical course is to build up a theoretical representation (N-body model) of the observed properties of the stellar stream associated to the globular cluster Palomar 5. Our priors are (i) a static (simplified) representation of the Milky Way potential, (ii) the position on the sky of the cluster remnant core, (iii) its heliocentric radial velocity, and (iv) its heliocentric distance.

We use the position of the stellar stream as detected in the Sloan Digital Sky Survey (SDSS) (see Grillmair and Dionatos, 2006) as observational constraints on the free-parameters of our models, which in this simplistic exercise correspond to the 2D-tangential components of the current velocity vector (i.e., proper motions) of Pal 5. Note that there are available measurements of Pal 5 proper motions. However, measuring those quantities for stellar systems as faint MV = —4.77 ± 0.20 and distant (D ≃ 21 kpc) as Pal 5 is subject to large observational uncertainties that translate into poorly constrained Galactocentric orbital parameters. To illustrate this issue, we adopt the Galactocentric proper motions of Pal 5 (μα,μδ) as free parameters that we derive from fitting the orientation of the stellar stream on the sky, and compare their values with measurements available in the literature. The second main goal of the exercise is thus to inspect the reliability of the existing proper motion measurements for Pal 5.

Type
Chapter
Information
Local Group Cosmology , pp. 226 - 232
Publisher: Cambridge University Press
Print publication year: 2013

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References

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