Eclipse timing the Milky Way's gravitational potential

Understand

We show that a small, but \textit{measurable} shift in the eclipse mid-point time of eclipsing binary (EBs) stars of $\sim$ 0.1 seconds over a decade baseline can be used to directly measure the Galactic acceleration of stars in the Milky Way at $\sim$ kpc distances from the Sun.

• We consider contributions to the period drift rate from dynamical mechanisms other than the Galaxy's gravitational field, and show that the Galactic acceleration can be reliably measured using a sample of $\textit{Kepler}$ EBs with orbital and stellar parameters from the literature.
• Given the uncertainties on the formulation of tidal decay, our approach here is necessarily approximate, and the contribution from tidal decay is an upper limit assuming the stars are not tidally synchronized.
• We also use simple analytic relations to search for well-timed sources in the \textit{Kepler} field, and find $\sim$ 70 additional detached EBs with low eccentricities that have estimated timing precision better than 1 second.