Astrometric Microlensing of Primordial Black Holes with Gaia

Understand

The Gaia space telescope allows for unprecedented accuracy for astrometric measurements of stars in the Galaxy.

• In this work, we explore the sensitivity of Gaia to detect primordial black hole (PBH) dark matter through the distortions that PBHs would create in the apparent trajectories of background stars, an effect known as astrometric microlensing (AML).
• We present a novel calculation of the lensing probability, and we combine this with the existing publicly released Gaia eDR3 stellar catalog to predict the expected rate of AML events that Gaia will see.
• We also compute the expected distribution of a few event observables, which will be useful for reducing backgrounds.