Kavli Affiliate: Lina Necib
| First 5 Authors: Cian Roche, Lina Necib, Tongyan Lin, Xiaowei Ou, Tri Nguyen
| Summary:
The escape velocity profile of the Milky Way offers a crucial and independent
measurement of its underlying mass distribution and dark matter properties.
Using a sample of stars from Gaia DR3 with 6D kinematics and strict quality
cuts, we obtain an escape velocity profile of the Milky Way from 4 kpc to 11
kpc in Galactocentric radius. To infer the escape velocity in radial bins, we
model the tail of the stellar speed distribution with both traditional power
law models and a new functional form that we introduce. While power law models
tend to rely on extrapolation to high speeds, we find our new functional form
gives the most faithful representation of the observed distribution. Using this
for the escape velocity profile, we constrain the properties of the Milky Way’s
dark matter halo modeled as a Navarro-Frenck-White profile. Combined with
constraints from the circular velocity at the solar position, we obtain a
concentration and mass of $c_{200rm{c}}^{rm{DM}} = 13.9^{+6.2}_{-4.3}$ and
$rm{M}_{200rm{c}}^{rm{DM}} = 0.55^{+0.15}_{-0.14}times 10^{12} M_odot$.
This corresponds to a total Milky Way mass of $rm{M}_{200rm{c}} =
0.64^{+0.15}_{-0.14}times 10^{12} M_odot$, which is on the low end of the
historic range of the Galaxy’s mass, but in line with other recent estimates.
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