The local high velocity tail and the Galactic escape speed

Abstract

We model the fastest moving (v_tot > 300 km/s) local (D < 3 kpc) halo stars using cosmological simulations and 6-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 (M_star ~ 10^9 M_Sun) 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 2r_200, beyond which stars can escape. After applying our methodology to the Gaia data, we find a local (r_0=8.3 kpc) escape speed of v_esc(r_0) = 528(+24,-25) km/s. We use our measurement of the escape velocity to estimate the total Milky Way mass, and dark halo concentration: M_200,tot = 1.00(+0.31,-0.24) x 10^12 M_Sun, c_200 = 10.9(+4.4,-3.3). Our estimated mass agrees with recent results in the literature that seem to be converging on a Milky Way mass of M_200,tot ~ 10^12 M_Sun.

arXiv comment13 pages, 10 Figures. MNRAS accepted

References in corpus (67)

• A Universal Density Profile from Hierarchical Clustering
• Gaia Data Release 2. Summary of the contents and survey properties
• The Structure of Cold Dark Matter Halos
• The Gaia mission
• Planck 2013 results. XVI. Cosmological parameters
• The EAGLE project: Simulating the evolution and assembly of galaxies and their environments
• E pur si muove: Galiliean-invariant cosmological hydrodynamical simulations on a moving mesh
• Statistical Properties of X-ray Clusters: Analytic and Numerical Comparisons
• Local Kinematics and the Local Standard of Rest
• The Galaxy in Context: Structural, Kinematic and Integrated Properties
• The EAGLE simulations of galaxy formation: calibration of subgrid physics and model variations
• The merger that led to the formation of the Milky Way's inner stellar halo and thick disk
• Co-formation of the Galactic disc and the stellar halo
• Cold dark matter haloes in the Planck era: evolution of structural parameters for Einasto and NFW profiles
• The Milky Way's bright satellites as an apparent failure of LCDM
• Concentration, Spin and Shape of Dark Matter Haloes as a Function of the Cosmological Model: WMAP1, WMAP3 and WMAP5 results
• LCDM-based models for the Milky Way and M31 I: Dynamical Models
• The RAVE Survey: Constraining the Local Galactic Escape Speed
• The Auriga Project: the properties and formation mechanisms of disc galaxies across cosmic time
• The properties of warm dark matter haloes
• Ejection of hypervelocity stars by the (binary) black hole(s) in the Galactic center
• The Circular Velocity Curve of the Milky Way from $5$ to $25$ kpc
• Baryon effects on the internal structure of LCDM halos in the EAGLE simulations
• Discovery of an Unbound Hyper-Velocity Star in the Milky Way Halo
• In disguise or out of reach: first clues about in-situ and accreted stars in the stellar halo of the Milky Way from Gaia DR2
• The Dual Origin of Stellar Halos
• The Mass-Concentration-Redshift Relation of Cold and Warm Dark Matter Halos
• The Milky Way stellar halo out to 40 kpc : Squashed, broken but smooth
• The RAVE survey: the Galactic escape speed and the mass of the Milky Way
• Proper motions and dynamics of the Milky Way globular cluster system from Gaia DR2
• Three Hypervelocity White Dwarfs in Gaia DR2: Evidence for Dynamically Driven Double-Degenerate Double-Detonation Type Ia Supernovae
• Mass and shape of the Milky Way's dark matter halo with globular clusters from Gaia and Hubble
• The Milky Way Tomography with SDSS: III. Stellar Kinematics
• The Space Motion of Leo I: The Mass of the Milky Way's Dark Matter Halo
• The Mass of the Milky Way Galaxy
• The Auriga Stellar Haloes: Connecting stellar population properties with accretion and merging history
• The Missing Massive Satellites of the Milky Way
• The Shape and Profile of the Milky Way Halo as Seen by the CFHT Legacy Survey
• Kinematics of SDSS subdwarfs: Structure and substructure of the Milky Way halo
• The mass of the Milky Way from satellite dynamics
• Constraining the WDM Particle Mass with Milky Way Satellites
• Formation of In Situ Stellar Haloes in Milky Way-Mass Galaxies
• Apocenter Pile-Up: Origin of the Stellar Halo Density Break
• The characteristics of high velocity O and B stars which are ejected from supernovae in binary systems
• The origin of galactic metal-rich stellar halo components with highly eccentric orbits
• Constraining the Milky Way Halo Potential with the GD-1 stellar stream
• The escape speed curve of the Galaxy obtained from Gaia DR2 implies a heavy Milky Way
• A new way of setting the phases for cosmological multi-scale Gaussian initial conditions
• The Milky Way Halo in Action Space
• Rotation of Halo Populations in the Milky Way and M31
• Revisiting hypervelocity stars after Gaia DR2
• The first all-sky view of the Milky Way stellar halo with Gaia+2MASS RR Lyrae
• The slight spin of the old stellar halo
• On the Run: mapping the escape speed across the Galaxy with SDSS
• Properties of HI discs in the Auriga cosmological simulations
• Milky Way mass constraints from the Galactic satellite gap
• A Milky Way with a massive, centrally concentrated thick disc: new Galactic mass models for orbit computations
• The imprint of cosmic reionisation on the luminosity function of galaxies
• Simple Three-Integral Scale-Free Galaxy Models
• Bailing Out the Milky Way: Variation in the Properties of Massive Dwarfs Among Galaxy-Sized Systems
• Old, Metal-Poor Extreme Velocity Stars in the Solar Neighborhood
• Estimating the Mass of the Milky Way Using the Ensemble of Classical Satellite Galaxies
• A Dipole on the Sky: Predictions for Hypervelocity Stars from the Large Magellanic Cloud
• The Fastest Travel Together: Chemical Tagging of the Fastest Stars in Gaia DR2 to the Stellar Halo
• Nearby high-speed stars in Gaia DR2
• A skewer survey of the Galactic halo from deep CFHT and INT images
• RR Lyrae in XSTPS: The halo density profile in the North Galactic Cap

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