Astronomers may have discovered the first free-floating black hole in the Milky Way galaxy, thanks to a technique called gravitational microlensing. With new observations, they hope to find many more such ghost stars. (Video by Roxanne Makasdjian and Alan Toth, with microlensing animations from Casey Lam and Sean Terry, UC Berkeley’s Moving Universe Lab, and image data courtesy of the OGLE collaboration. Additional images courtesy of the National Science Foundation and NASA.)
A team of astronomers led by UC Berkeley graduate student Casey Lam and associate professor Jessica Lu has for the first time discovered what may be a free-floating black hole by observing the brightening of a more distant star as its light was distorted by the object’s strong gravitational field — so-called gravitational microlensing.