Program: GS-2024A-FT-111

Binary evolution models predict the existence of compact objects in binaries with main sequence companions in wide-period orbits. Although long sought-after, nearly every detection of such a binary has been shown to be spurious. However, the recent third data release from Gaia has identified >100,000 binaries with astrometric orbital solutions, from which a few remarkable systems have already been detected. Among the remaining candidates, we have identified one system that not only has a large astrometric mass function suggesting a massive (~10 Msun) black hole, but emits X-rays as detected by eROSITA indicating low-luminosity accretion. Over the course of 2 months, we propose to obtain three high resolution, high SNR spectra to confirm the astrometric orbit, as measured by Gaia.