The effects of dynamical substructure on Milky Way mass estimates from the high-velocity tail of the local stellar halo

  title={The effects of dynamical substructure on Milky Way mass estimates from the high-velocity tail of the local stellar halo},
  author={Robert J. J. Grand and Alis J. Deason and Simon D. M. White and Christine M. Simpson and Facundo A. G'omez and Federico Marinacci and R{\"u}diger Pakmor},
  journal={Monthly Notices of the Royal Astronomical Society: Letters},
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… 

Figures from this paper

The mass of the Milky Way out to 100 kpc using halo stars

We use a distribution function analysis to estimate the mass of the Milky Way out to 100 kpc using a large sample of halo stars. These stars are compiled from the literature, and the majority (~95%)

Substructure at High Speed. II. The Local Escape Velocity and Milky Way Mass with Gaia eDR3

Measuring the escape velocity of the Milky Way is critical in obtaining the mass of the Milky Way, understanding the dark matter velocity distribution, and building the dark matter density profile.

Determination of the escape velocity of the Milky Way using a halo sample selected based on proper motion

Context. The Gaia mission has provided the largest catalogue ever of sources with tangential velocity information. However, it is difficult to use this catalogue for dynamical studies because most of

Substructure at High Speed. I. Inferring the Escape Velocity in the Presence of Kinematic Substructure

The local escape velocity provides valuable inputs to the mass profile of the galaxy, and requires understanding the tail of the stellar speed distribution. Following Leonard & Tremaine, various

The Global Structure of the Milky Way’s Stellar Halo Based on the Orbits of Local Metal-poor Stars

We analyze the global structure of the Milky Way (MW)'s stellar halo, including its dominant subcomponent, Gaia-Sausage-Enceladus (GSE). The method for reconstructing the global distribution of this

Constraining the Milky Way Mass Profile with Phase-space Distribution of Satellite Galaxies

We estimate the Milky Way (MW) halo properties using satellite kinematic data including the latest measurements from Gaia DR2. With a simulation-based 6D phase-space distribution function (DF) of

The milky way total mass profile as inferred from Gaia DR2

We determine the Milky Way (MW) mass profile inferred from fitting physically motivated models to the Gaia DR2 Galactic rotation curve and other data. Using various hydrodynamical simulations of

The dark matter component of the Gaia radially anisotropic substructure

We study the properties of the dark matter component of the radially anisotropic stellar population recently identified in the Gaia data, using magneto-hydrodynamical simulations of Milky Way-like

On the Absence of Dark Matter in Dwarf Galaxies Surrounding the Milky Way

This paper presents an alternative scenario to explain the observed properties of the Milky Way dwarf Spheroidals (MW dSphs). We show that instead of resulting from large amounts of dark matter (DM),

The edge of the Galaxy

We use cosmological simulations of isolated Milky Way (MW)-mass galaxies, as well as Local Group (LG) analogues, to define the ‘edge’ – a caustic manifested in a drop in density or radial velocity



The Auriga stellar haloes: connecting stellar population properties with accretion and merging history

We examine the stellar haloes of the Auriga simulations, a suite of 30 cosmological magnetohydrodynamical high-resolution simulations of Milky Way-mass galaxies performed with the moving-mesh code

The mass of the Milky Way from satellite dynamics

We present and apply a method to infer the mass of the Milky Way (MW) by comparing the dynamics of MW satellites to those of model satellites in the eagle cosmological hydrodynamics simulations. A

The local high-velocity tail and the Galactic escape speed

We model the fastest moving (⁠v tot >300kms −1 vtot>300kms−1 ⁠) local (D ≲ 3 kpc) halo stars using cosmological simulations and six-dimensional Gaia data. Our approach is to use our knowledge of

The RAVE survey : the Galactic escape speed and the mass of the Milky Way

We made new estimates of the Galactic escape speed at various Galactocentric radii using the latest data release of the RAdial Velocity Experiment (RAVE DR4). Compared to previous studies we have a

The merger that led to the formation of the Milky Way’s inner stellar halo and thick disk

It is demonstrated that the inner halo of the Galaxy is dominated by debris from an object that at infall was slightly more massive than the Small Magellanic Cloud, and which the authors refer to as Gaia–Enceladus, which is in line with the results of galaxy formation simulations.

Connecting the Milky Way potential profile to the orbital time-scales and spatial structure of the Sagittarius Stream

Recent maps of the halo using RR Lyrae from Pan-STARRS1 depict the spatial structure of the Sagittarius stream, showing the leading and trailing stream apocentres differ in Galactocentric radius by a

Evidence for an Intermediate-mass Milky Way from Gaia DR2 Halo Globular Cluster Motions

We estimate the mass of the Milky Way (MW) within 21.1 kpc using the kinematics of halo globular clusters (GCs) determined by Gaia. The second Gaia data release (DR2) contained a catalog of absolute

Streams in the Aquarius stellar haloes

We use the very high resolution, fully cosmological simulations from the Aquarius Project, coupled to a semi-analytical model of galaxy formation, to study the phase-space distribution of halo stars

A box full of chocolates: The rich structure of the nearby stellar halo revealed by Gaia and RAVE

The hierarchical structure formation model predicts that stellar halos should form, at least partly, via mergers. If this was a predominant formation channel for the Milky Way's halo, imprints of

The phase-space structure of cold dark matter haloes : insights into the Galactic halo

We study the formation of the halo of the Milky Way in a A-cold dark matter (ACDM) cosmology by scaling down a high-resolution simulation of the formation of a cluster of galaxies. We determine how