The RAVE survey: the Galactic escape speed and the mass of the Milky Way
  We construct new estimates on 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 database larger
by a factor of 10 as well as reliable distance estimates for almost all stars.
Our analysis is based on the statistical analysis of a rigorously selected
sample of 90 high-velocity halo stars from RAVE and a previously published data
set. We calibrate and extensively test our method using a suite of cosmological
simulations of the formation of Milky Way-sized galaxies. Our best estimate of
the local Galactic escape speed, which we define as the minimum speed required
to reach three virial radii $R_{340}$, is $533^{+54}_{-41}$ km/s (90%
confidence) with an additional 5% systematic uncertainty, where $R_{340}$ is
the Galactocentric radius encompassing a mean over-density of 340 times the
critical density for closure in the Universe. From the escape speed we further
derive estimates of the mass of the Galaxy using a simple mass model with two
options for the mass profile of the dark matter halo: an unaltered and an
adiabatically contracted Navarro, Frenk & White (NFW) sphere. If we fix the
local circular velocity the latter profile yields a significantly higher mass
than the un-contracted halo, but if we instead use the statistics on halo
concentration parameters in large cosmological simulations as a constraint we
find very similar masses for both models. Our best estimate for $M_{340}$, the
mass interior to $R_{340}$ (dark matter and baryons), is $1.3^{+0.4}_{-0.3}
\times 10^{12}$ M$_\odot$ (corresponding to $M_{200} = 1.6^{+0.5}_{-0.4} \times
10^{12}$ M$_\odot$). This estimate is in good agreement with recently published
independent mass estimates based on the kinematics of more distant halo stars
and the satellite galaxy Leo I.
