The effects of dynamical substructure on Milky Way mass estimates from the high velocity tail of the local stellar halo
arXiv:1905.09834 · doi:10.1093/mnrasl/slz092
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, magneto-hydrodynamical cosmological zoom-in simulations, which 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 , 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 .
Accepted to the Monthly Notices of the Royal Astronomical Society, Letters, with minor revision
References in corpus (6)
- The Auriga Project: the properties and formation mechanisms of disc galaxies across cosmic time
- The Streams of the Gaping Abyss: A population of entangled stellar streams surrounding the Inner Galaxy
- A box full of chocolates: The rich structure of the nearby stellar halo revealed by Gaia and RAVE
- Halo Substructure in the SDSS-Gaia Catalogue : Streams and Clumps
- The local high velocity tail and the Galactic escape speed
- The kpc Distant Spur of the Sagittarius Stream and the Outer Virgo Overdensity, as Seen in PS1 RR Lyrae Stars