Median Statistics Estimate of the Galactic Rotational Velocity

TL;DR

This paper compiles recent independent measurements of the Milky Way's rotational velocity, using median statistics to estimate it as 220 km/s with a 10 km/s uncertainty, providing a reliable summary of current data.

Contribution

It presents a new compilation of independent measurements of the Galactic rotational velocity and applies median statistics to derive a robust estimate.

Findings

Median estimate of $ heta_0$ is 220 km/s with 10 km/s error.

19 independent measurements compiled since 2000.

Distribution of measurements is mildly non-Gaussian.

Abstract

We compile a complete collection of 19 recent (since 2000) measurements of $\Theta_0$, the rotational velocity of the Milky Way at $R_0$ (the radial distance of the Sun from the Galactic center). These measurements use tracers that are believed to more accurately reflect the systematic rotation of the Milky Way. Unlike other recent compilations of $\Theta_0$, our collection includes only independent measurements. We find that these 19 measurements are distributed in a mildly non-Gaussian fashion and a median statistics estimate indicates $\Theta_0 = 220\ \pm 10$ km\,s$^{-1}$ (2$\sigma$ error) as the most reliable summary, at $R_0 = 8.0 \pm 0.3$ kpc (2$\sigma$ error).