Gaia DR3 Compact Binary Candidates Constrained by Radial Velocity Measurements

Abstract

Astrometry enables the most direct determination of the orbital elements and component masses of compact binaries. The potential of the current Gaia data for this purpose has not yet been fully explored. In this work, we combine Gaia astrometric and radial velocity (RV) measurements to perform joint orbital fitting for 1,835 Gaia astrometric binaries with available RV data. Among the 518 systems with at least three effective RV epochs, we identify 171 compact binary candidates, including four with inferred dark companion masses exceeding 2.1 $M_{\odot}$ and 22 between 1.4 and 2.1 $M_{\odot}$. These candidates provide valuable targets for future follow-up observations and Gaia DR4 analyses. We also flag 1,317 additional potential compact binary candidates with effective RV epochs less than three, including 84 with inferred companion masses above 2.1 $M_{\odot}$ and 173 between 1.4 and 2.1 $M_{\odot}$. More importantly, our results point to a large, currently hidden population of black hole and neutron star binaries that can be further explored with the forthcoming Gaia DR4 data and complementary follow-up observations.