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Fading features found in the kinematics of the far-reaching Milky Way stellar halo

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posted on 2024-07-26, 14:09 authored by Sarah A. Bird, Christopher FlynnChristopher Flynn
We test the long-term kinematical stability of a Galactic stellar halo model, due to Kafle et al. (2012), who study the kinematics of approximately 5000 blue horizontal branch (BHB) stars in the Sloan Digital Sky Survey (SDSS). The velocity dispersion σ and anisotropy parameter β of the stars have been determined as functions of Galactocentric radius, over the range 6 < RGC < 25 kpc, and show a strong dip in the anisotropy profile at RGC ∼ 17 kpc. By directly integrating orbits of particles in a 3-D model of the Galactic potential with these characteristics, we show that the σ and β profiles quickly evolve on a time scale of a few × 10 Myr whereas the density ρ profile remains largely unaffected. We suggest that the feature is therefore transient. The origin of such features in the Galactic halo remains unclear.

Funding

Emil Aaltosen Säätiö

Finnish Cultural Foundation

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ISSN

0035-8711

Journal title

Mon. Not. R. Astron. Soc.

Volume

452

Issue

3

Pagination

4 pp

Publisher

Oxford University Press

Copyright statement

Copyright © 2015. This article has been accepted for publication in the Monthly Notices of the Royal Astronomical Society ©: 2015 The authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.

Language

eng

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