Abstract
We show that a small but measurable shift in the eclipse midpoint time of eclipsing binary (EBs) stars of 0.1 s over a decade baseline can be used to directly measure the Galactic acceleration of stars in the Milky Way at kiloparsec 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 Kepler EBs with orbital and stellar parameters from the literature. The contribution from tidal decay we estimate here is an upper limit assuming the stars are not tidally synchronized. We find there are about 200 detached EBs that have estimated timing precision better than 0.5 s, and for which other dynamical effects are subdominant to the Galactic signal. We illustrate the method with a prototypical, precisely timed EB using an archival Kepler light curve and a modern synthetic HST light curve (which provides a decade baseline). This novel method establishes a realistic possibility to constrain dark matter substructure and the Galactic potential using eclipse timing to measure Galactic accelerations, along with other emerging new methods, including pulsar timing and extreme-precision radial velocity observations. This acceleration signal grows quadratically with time. Therefore, given baselines established in the near future for distant EBs, we can expect to measure the period drift in the future with space missions like JWST and the Roman Space Telescope.
Original language | English (US) |
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Article number | L17 |
Journal | Astrophysical Journal Letters |
Volume | 928 |
Issue number | 2 |
DOIs | |
State | Published - Apr 1 2022 |
Externally published | Yes |
Bibliographical note
Funding Information:S.C. gratefully acknowledges support from NSF AAG 2009574 and hospitality provided by the CCA at the Flatiron Institute. R.R.R. is supported by STFC grant ST/T00049X/1. We thank N. Sehgal for coining the word “optical timing.” We are grateful to S. Tremaine for helpful comments on the paper and for catching an error on the value of the apsidal motion constant. We thank J. Winn, R. Dawson, G. Ogilvie, A. Prsa, and J. Pepper for helpful discussions and the anonymous referee for helpful comments.
Funding Information:
The Center for Exoplanets and Habitable Worlds and the Penn State Extraterrestrial Intelligence Center are supported by the Pennsylvania State University and the Eberly College of Science.
Publisher Copyright:
© 2022. The Author(s). Published by the American Astronomical Society.