Eclipse Timing the Milky Way’s Gravitational Potential

Abstract We show that a small but measurable shift in the eclipse midpoint time of eclipsing binary (EBs) stars ∼0.1 s over decade baseline can be used to directly measure Galactic acceleration Milky Way at ∼kiloparsec distances from Sun. consider contributions period drift rate dynamical mechanisms other than Galaxy’s gravitational field and reliably measured using sample Kepler EBs with orbital stellar parameters literature. The contribution tidal decay we estimate here is an upper limit assuming are not tidally synchronized. find there about 200 detached have estimated timing precision better 0.5 s, for which effects subdominant signal. illustrate method prototypical, precisely timed EB archival light curve modern synthetic HST (which provides baseline). This novel establishes realistic possibility constrain dark matter substructure potential accelerations, along emerging new methods, including pulsar extreme-precision radial velocity observations. signal grows quadratically time. Therefore, given baselines established near future distant EBs, expect space missions like JWST Roman Space Telescope.