Robert JJ Grand
The effects of dynamical substructure on Milky Way mass estimates from the high-velocity tail of the local stellar halo
Grand, Robert JJ; Deason, Alis J; White, Simon DM; Simpson, Christine M; Gómez, Facundo A; Marinacci, Federico; Pakmor, Rüdiger
Authors
Dr Alis Deason alis.j.deason@durham.ac.uk
Associate Professor
Simon DM White
Christine M Simpson
Facundo A Gómez
Federico Marinacci
Rüdiger Pakmor
Abstract
We investigate the impact of dynamical streams and substructure on estimates of the local escape speed and total mass of Milky-Way-mass galaxies from modelling the high-velocity tail of local halo stars. We use a suite of high-resolution magnetohydrodynamical cosmological zoom-in simulations that resolve phase space substructure in local volumes around solar-like positions. We show that phase space structure varies significantly between positions in individual galaxies and across the suite. Substructure populates the high-velocity tail unevenly and leads to discrepancies in the mass estimates. We show that a combination of streams, sample noise, and truncation of the high-velocity tail below the escape speed leads to a distribution of mass estimates with a median that falls below the true value by ∼20 per cent ∼20 per cent , and a spread of a factor of 2 across the suite. Correcting for these biases, we derive a revised value for the Milky Way mass presented in Deason et al. of 1.29 +0.37 −0.47 × 10 12 M ⊙ 1.29−0.47+0.37×1012M⊙ .
Citation
Grand, R. J., Deason, A. J., White, S. D., Simpson, C. M., Gómez, F. A., Marinacci, F., & Pakmor, R. (2019). The effects of dynamical substructure on Milky Way mass estimates from the high-velocity tail of the local stellar halo. Monthly Notices of the Royal Astronomical Society: Letters, 487(1), L72-L76. https://doi.org/10.1093/mnrasl/slz092
Journal Article Type | Article |
---|---|
Acceptance Date | Jun 3, 2019 |
Online Publication Date | Jun 18, 2019 |
Publication Date | Jul 31, 2019 |
Deposit Date | Sep 13, 2019 |
Publicly Available Date | Sep 13, 2019 |
Journal | Monthly Notices of the Royal Astronomical Society: Letters |
Electronic ISSN | 1745-3933 |
Publisher | Oxford University Press |
Peer Reviewed | Peer Reviewed |
Volume | 487 |
Issue | 1 |
Pages | L72-L76 |
DOI | https://doi.org/10.1093/mnrasl/slz092 |
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Copyright Statement
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society: Letters ©: 2019 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
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