Daniel CleryFar away in the depths of space, two black holes spiral toward each other and merge. Powerful gravitational waves from that dance of death race across the cosmos until their ripples reach three giant detectors on Earth: two with the U.S.-based Laser Interferometer Gravitational-wave Observatory (LIGO) and Europe’s Virgo detector in Italy.The detectors have sensed dozens of such cataclysms over the past 5 years, but the one on 21 May 2019 was different.
Not only was it the most powerful and distant merger ever seen, but the resulting black hole also belongs to class of long-sought middleweight black holes, members of the LIGO-Virgo collaboration report today in two new studies.