Galactic Potential and Dark Matter Density from Angular Stellar Accelerations

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 similar to 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.

Automated summary

This study introduces a new method for measuring the Milky Way potential using the angular accelerations of stars in aggregate. The findings suggest that it is possible to measure the potential of the MW disk and the local dark matter density at different significance levels. In the future, combining different astronomical surveys may lead to precise measurements of the local dark matter density and the shape of its density profile.