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Grand, RJJ, Deason, AJ, White, SDM, Simpson, CM, Gómez, FA, Marinacci, F and 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). L720-LL76. ISSN 1745-3925
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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 ${\sim } 20 {{\ \rm per\ cent}}$, 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 $1.29 ^{+0.37}_{-0.47} \times 10^{12}\, \rm M_{\odot }$.
| Item Type: | Article |
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| Additional Information: | This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2019 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. |
| Uncontrolled Keywords: | 0201 Astronomical and Space Sciences |
| Subjects: | Q Science > QB Astronomy Q Science > QC Physics |
| Divisions: | Astrophysics Research Institute |
| Publisher: | Oxford University Press (OUP) |
| SWORD Depositor: | A Symplectic |
| Date Deposited: | 19 Apr 2023 11:52 |
| Last Modified: | 19 Apr 2023 11:52 |
| DOI or ID number: | 10.1093/mnrasl/slz092 |
| URI: | https://researchonline.ljmu.ac.uk/id/eprint/19321 |
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