The Galactic potential and dark matter density from angular stellar accelerations

TL;DR

This paper proposes a novel method to measure the Milky Way's gravitational potential and local dark matter density by analyzing stellar angular accelerations from astrometric data, offering a direct approach that complements traditional velocity-based methods.

Contribution

The paper introduces a new technique to directly measure the MW potential and dark matter density using stellar angular accelerations from astrometric surveys like Gaia.

Findings

Gaia data can measure MW disk potential at ~3σ significance.

Including solar acceleration data allows measurement of local dark matter density at ~2σ significance.

Future surveys could significantly improve dark matter density and profile measurements.

Abstract

We present an approach to measure the Milky Way (MW) potential using the angular accelerations of stars in aggregate as measured by astrometric surveys like Gaia. Accelerations directly probe the gradient of the MW potential, as opposed to indirect methods using e.g. stellar velocities. We show that end-of-mission Gaia stellar acceleration data may be used to measure the potential of the MW disk at approximately 3$\sigma$ significance and, if recent measurements of the solar acceleration are included, the local dark matter density at ~2$\sigma$ significance. Since the significance of detection scales steeply as $t^{5/2}$ for observing time $t$, future surveys that include angular accelerations in the astrometric solutions may be combined with Gaia to precisely measure the local dark matter density and shape of the density profile.