A Precise Milky Way Rotation Curve Model for an Accurate Galactocentric Distance

TL;DR

This paper presents a detailed Milky Way rotation curve model that accurately matches recent terminal velocity data, enabling precise estimates of Galactic mass components and dark matter density, challenging the assumption of a spherical halo.

Contribution

It provides a new, precise rotation curve model of the Milky Way incorporating recent measurements, improving estimates of mass distribution and dark matter density.

Findings

Accurate rotation curve matching GRAVITY data

Precise stellar mass estimate of the Galaxy

Dark matter density lower than in some previous studies

Abstract

I provide a model rotation curve for the Milky Way that matches the details of the terminal velocity curve normalized to the Galactocentric distance $R_0 = 8.122$ kpc obtained by the GRAVITY collaboration and the corresponding circular speed of the LSR $\Theta_0 = 233.3$ km/s. The model provides a numerical representation of the azimuthally averaged radial run of the gravitational potential of each mass component of the Galaxy (bulge-bar, stellar disk, gas disk, and dark matter) as represented by the rotation curve of each. It provides precise estimates of quantities like the stellar mass of the Galaxy ($6.16 \pm 0.31 \times 10^{10}\;\mathrm{M}_{\odot}$) and the local density of dark matter ($\rho_{DM}(R_0) = 6.76^{+0.08}_{-0.14} \times 10^{-3}\; \mathrm{M}_{\odot}\,\mathrm{pc}^{-3} = 0.257^{+0.003}_{-0.005}\; \mathrm{GeV}\,\mathrm{cm}^{-3}$). The dark matter density implied by the radial force is less than that found in many studies of the vertical force, perhaps indicating that the usual assumption of a spherical dark matter halo is no longer adequate.