Seminar Series Abstracts: March 7

Gaia's Black Holes and Why they are Special

The discovery of gravitational waves from merging binary black holes and neutron stars has created unprecedented interest in improving our understanding of how high-mass stars evolve and form compact objects. Several theoretical studies, including ours, predict that Gaia by its end of mission should discover hundreds of black hole binaries with luminous companions through astrometry, photometry, spectroscopy, and their combinations. These predictions have already come true through analysis of Gaia's third data release. These systems are complementary to those discoverable through the detection of gravitational waves, X-ray, and radio emissions. The distribution of properties for Gaia's detectable population is identical to that of the intrinsic population, showing little observational biases based on the black hole properties. Furthermore, since Gaia itself provides the distance, magnitude, and colors for the luminous companions, it is relatively straightforward to constrain the metallicities and ages for the progenitors of the black holes, a constraint that is hard to come by for black holes discovered through other more traditional methods. We will talk about our recent key results on this.