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Galactic microlensing is the only known method for detecting dark objects ranging from isolated stellar-mass black holes (BHs) to low-mass free-floating planets (FFPs). Our success in the interferometric resolution of microlensed images with the VLTI has opened a new avenue for identifying isolated stellar remnants. I will discuss how VLTI-GRAVITY+ can potentially discover a large sample of BHs and uncover their distribution. Ground-based surveys have identified roughly a dozen short-timescale microlensing events, suggesting that FFPs may be a few times more common than planets bound to stars. Through joint observations from the ground and the Gaia satellite, we recently achieved the first lens mass measurement of an FFP event, finding a Saturn-mass planet. I will discuss how future space-based surveys can advance our understanding of the emerging FFP population.

BIO

Professor Subo Dong works in the Department of Astronomy, School of Physics, at Peking University. He obtained B.Sc. in Astronomy from Nanjing University in 2004 and Ph.D. in Astronomy from The Ohio State University in 2009. After conducting postdoctoral research at the Institute for Advanced Study in Princeton, he joined the faculty at Peking University in 2013. He is currently interested in searching for exoplanets and black holes with microlensing, studying the distribution and dynamical evolution of exoplanets, and understanding how supernovae explode.

Host: Wei Zhu