Mass Models of the Milky Way and Estimation of Its Mass from the Gaia DR3 Data Set

Abstract

We use data from the Gaia DR3 data set to estimate the mass of the Milky Way (MW) by analyzing the rotation curve in the range of distances 5 to 28 kpc. We consider three mass models: The first model adds a spherical dark matter (DM) halo, following the Navarro–Frenk–White (NFW) profile, to the known stellar components. The second model assumes that DM is confined to the Galactic disk, following the idea that the observed density of gas in the Galaxy is related to the presence of a more massive DM disk (DMD), similar to the observed correlation between DM and gas in other galaxies. The third model only uses the known stellar-mass components and is based on the Modified Newton Dynamics (MOND) theory. Our results indicate that the DMD model is comparable in accuracy to the NFW and MOND models and fits the data better at large radii where the rotation curve declines but has the largest errors. For the NFW model, we obtain a virial mass M _vir = (6.5 ± 0.3) × 10 ^11 M _⊙ with concentration parameter c = 14.5, which is lower than what is typically reported. In the DMD case, we find that the MW mass is M _d = (1.6 ± 0.5) × 10 ^11 M _⊙ with a disk’s characteristic radius of R _d = 17 kpc.

Keywords

• Milky Way Galaxy