Speaker
Description
One of the major scientific milestones of the Gaia mission has been the achievement of an improved stellar binary population census and the discovery of rare objects such as black hole (BH)-star binaries. High precision astrometric measurements of binary separations and mass ratios have an application in dark sector physics, as stellar binaries are highly sensitive to the spatial as well as the velocity distribution of perturbers. This makes them a sensitive probe of dissipative dark sectors, where a subcomponent of dark matter can cool to form a dark disk as well as dark compact objects (including black holes). In this work, we consider the observational implications of the existence of a dark disk on the formation rate of BH-star binaries by considering exchanges between dark perturbers and stellar (star-star) binaries. Unless the scale height of the dark disk equilibrates with the stellar thin disk, we find the rate of these exchange interactions is in excess of the rate expected from observations, arising largely due to the much smaller velocity dispersion of the dark compact objects within a dark disk which is co-rotating with the Standard Model galactic disk. Comparing with observation, we set potentially competitive constraints on the DDM parameter space, making the Gaia mission an important testbed for dissipative dark sector physics.