Description
Current estimates suggest that the Milky Way contains approximately 100 million stellar-mass black holes; however, only about 100 have been detected, mainly due to the bright X-ray signal resulting from rapid accretion events from a close binary partner. The population of black holes in wide, non-accreting binaries with a companion star, predicted to be around 10 million, remains elusive, with only a handful identified through astrometry and radial velocity techniques. I will present a novel methodological framework for detecting these quiet black holes through photometric gravitational lensing signatures in binary systems. Our approach builds on exoplanet transit detection methods, with the transit causing a lensing flare in place of a dip. We incorporate eccentric orbital dynamics leading to viewpoint-dependent variations in the Einstein radius, and self-consistent stellar limb darkening law, enabling multi-wavelength analyses. Initial simulations of plausible eccentric systems reveal characteristic asymmetric flux amplification of 0.1% to 2%, which should be detectable in high-cadence surveys such as TESS and ZTF. While these lensing signals are transient and sensitive to viewing geometry, our analysis indicates that high-inclination systems with periodic signatures and well-constrained orbital parameters could be identified through phase-resolved analysis. I will discuss how we may adapt existing exoplanet transit search pipelines for lensing detection and expectations for future detections.
