Tools
Tools
Deason, AJ, Fattahi, A, Belokurov, V, Wyn Evans, N, Grand, RJJ, Marinacci, F and Pakmor, R (2019) The local high-velocity tail and the Galactic escape speed. Monthly Notices of the Royal Astronomical Society, 485 (3). pp. 3514-3526. ISSN 0035-8711
|
Text
stz623.pdf - Published Version Download (1MB) | Preview |
Abstract
We model the fastest moving (vtot > 300 km s−1) local (D 3 kpc) halo stars using cosmological simulations and six-dimensional Gaia data. Our approach is to use our knowledge of the assembly history and phase-space distribution of halo stars to constrain the form of the high-velocity tail of the stellar halo. Using simple analytical models and cosmological simulations, we find that the shape of the high-velocity tail is strongly dependent on the velocity anisotropy and number density profile of the halo stars - highly eccentric orbits and/or shallow density profiles have more extended high-velocity tails. The halo stars in the solar vicinity are known to have a strongly radial velocity anisotropy, and it has recently been shown the origin of these highly eccentric orbits is the early accretion of a massive (Mstar ∼ 109 M☉) dwarf satellite. We use this knowledge to construct a prior on the shape of the high-velocity tail. Moreover, we use the simulations to define an appropriate outer boundary of 2r200, beyond which stars can escape. After applying our methodology to the Gaia data, we find a local (r0 = 8.3 kpc) escape speed of vesc(r0) = 528+−2425 km s−1. We use our measurement of the escape velocity to estimate the total Milky Way mass, and dark halo concentration: M200,tot = 1.00+−003124 × 1012 M☉, c200 = 10.9+−4343. Our estimated mass agrees with recent results in the literature that seem to be converging on a Milky Way mass of M200,tot ∼ 1012 M☉.
| Item Type: | Article |
|---|---|
| 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; Astronomy & Astrophysics |
| 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 11:43 |
| Last Modified: | 19 Apr 2023 11:43 |
| DOI or ID number: | 10.1093/mnras/stz623 |
| URI: | https://researchonline.ljmu.ac.uk/id/eprint/19328 |
 |
View Item |