Milky Way: New Galactic mass model for orbit computations

Abstract

Accurate observational data on the rotation curve of the Milky Way galaxy (MW) are very well understood using the gravitational potentials of the baryonic matter (Pouliasis et al., 2017) and the interpolating function presented by McGaugh et al. (2016). In this way we couple the spherically symmetric mass distribution of the dark matter (DM) to the mass distribution of the baryonic matter (BM). A commonly used model of the dark matter distribution can be understood as an approximation of our model. Creation of a new Galactic mass model for orbit computations based on the coupling of the DM with an improved BM model respecting the theoretical fit of the Galactic rotation curve. The theoretical approach is based on a slight improvement of the BM model by Pouliasis et al. (2017) and on replacement of their DM model by the model based on the interpolating function by McGaugh et al. (2016). The theoretical results are validated by the comparison with observational data. New Galactic mass model for orbit computations is created. DM distribution is given and the rotation curve for the MW is consistent with observational data. The Tully-Fisher relation holds and the values of several characteristics of the MW for the region of the Sun are given, e.g., rotation speed $v_0$ = ($228.8 \pm 0.2$) ~ \mbox{km} \mbox{s}$^{-1}$, Oort constants $A=(+14.73 \pm 0.03) ~\mbox{km} ~\mbox{s}^{-1} ~\mbox{kpc}^{-1} $, $B=(-13.01 \pm 0.03) ~\mbox{km} ~\mbox{s}^{-1} ~\mbox{kpc}^{-1}$ and the mass density of the baryonic matter $(0.087 \pm 0.001) ~\mbox{M}_{\odot} ~\mbox{pc}^{-3} $. Important MW characteristics are the total BM mass $M_{BM}$ $=$ (8.43 $\pm$ 0.01) $\times$ 10$^{10}$ $\mbox{M}_{\odot}$, the total DM mass $M_{DM}$ $\doteq$ (1.34 $\pm$ 0.01) $\times$ 10$^{12}$ $\mbox{M}_{\odot}$, virial radius and virial mass of the MW, $M_{vir}$ $\doteq$ $M_{DM}$.