Uncovering the Galactic Black Hole Population with Gravitational Microlensing

Nov 29, 2022 - 10:40 am to 11:30 am

Campus, PAB 102/103

Casey Lam (UC Berkeley) zoom https://stanford.zoom.us/j/550904854

Zoom info: https://stanford.zoom.us/j/550904854

There are expected to be 100 million black holes (BHs) in the Milky Way. Although a substantial fraction of these BHs are expected to be isolated, until recently Galactic BH mass measurements existed only for two dozen BHs in X-ray binary systems. This leaves large uncertainty in the properties of the Galactic BH population. Detection of isolated BHs would enable the comparison of the single vs. binary BH mass distributions, which in turn would enable improved understand of massive star death and BH formation channels. In this talk I will discuss the search for isolated black holes via gravitational microlensing. I will explain how photometric microlensing can statistically constrain the Galactic black hole population, then present the detection of an isolated low-mass BH or neutron star made with astrometric microlensing.