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TAPIR Seminar

Friday, October 21, 2022
2:00pm to 3:00pm
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Online and In-Person Event
Uncovering the Galactic Black Hole Population with Gravitational Microlensing
Casey Lam, Graduate Student, U.C. Berkeley, Department of Astronomy,


In person: 370 Cahill -- Attendees joining in person must have a valid Caltech UID.

To Join via Zoom:


There are expected to be 100 million black holes (BHs) in the Milky Way, although until recently mass measurements existed for only two dozen or so in X-ray binary systems. A substantial fraction of the Milky Way's BHs are expected to be isolated. This leaves large uncertainty in the number, masses, velocities, and formation channels 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. In the first part, I will discuss how photometric microlensing can statistically constrain the Galactic black hole population. In the second part, I will present the detection of an isolated low-mass BH or neutron star with astrometric microlensing.

For more information, please contact JoAnn Boyd by phone at 626-395-4280 or by email at [email protected].