On The Exoplanet Yield Of Gaia Astrometry

We re-examine the expected yield of Gaia astrometric planet detections using updated models for giant-planet occurrence, the local stellar population, and Gaia’s demonstrated astrometric precision.

Our analysis combines a semi-analytic model that clarifies key scaling relations with more realistic Monte Carlo simulations. We predict 7,500±2,100 planet discoveries in the 5-year dataset (DR4) and 120,000±22,000 over the full 10-year mission (DR5), with the dominant error arising from uncertainties in giant-planet occurrence.

We evaluate the sensitivity of these forecasts to the detection threshold and the desired precision for measurements of planet masses and orbital parameters. Roughly 1,900±540 planets in DR4 and 38,000±7,300 planets in DR5 should have masses and orbital periods determined to better than 20%.

Most detections will be super-Jupiters (3 – 13M_J) on 2 – 5AU orbits around GKM-type stars (0.4 – 1.3M_⊙) within 500 pc. Unresolved binary stars will lead to spurious planet detections, but we estimate that genuine planets will outnumber them by a factor of 5 or more. An exception is planets around M-dwarfs with a<1AU, for which the false-positive rate is expected to be about 50%.

To support community preparation for upcoming data releases, we provide mock catalogs of Gaia exoplanets and planet-impostor binaries.

Caleb Lammers, Joshua N. Winn

Comments: 27 pages, 15 figures. Under review at AJ. Catalogs and code available at this https URL
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Cite as: arXiv:2511.04673 [astro-ph.EP] (or arXiv:2511.04673v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2511.04673
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Submission history
From: Caleb Lammers
[v1] Thu, 6 Nov 2025 18:57:00 UTC (11,905 KB)
https://arxiv.org/abs/2511.04673

Astrobiology, exoplanet,