LIGO and Virgo announce 39 new gravitational wave discoveries during first half of third observing run

LIGO and Virgo announce 39 new gravitational wave discoveries during first half of third observing run
The LIGO Scientific Collaboration and Virgo Collaboration released a catalog of results from the first half of its third observing run (O3a). This shows the masses of the black holes and neutron stars in the 50 gravitational wave events detected to date. Credit: LIGO-Virgo/Frank Elavsky, Aaron Geller/Northwestern

The LIGO Scientific Collaboration and Virgo Collaboration released a catalog of results from the first half of its third observing run (O3a), and scientists have detected more than three times as many gravitational waves than the first two runs combined. Gravitational waves were first detected in 2015 and are ripples in time and space produced by merging black holes and/or neutron stars. Several researchers from Rochester Institute of Technology’s Center for Computational Relativity and Gravitation (CCRG) were heavily involved in analyzing the gravitational waves and understanding their significance.


The catalog details 39 new gravitational wave events detected during O3a, bringing the total to 50, and several of the newly detected binaries have unique properties that expand our understanding of binary black hole formation. O3a uncovered the largest and smallest binary black holes to date, ranging from 150 times the size of our sun to just 3 times larger. O3a also detected the first binary black hole confidently formed from highly asymmetrical black holes as well as several binary black holes with unique spin properties.

Jacob Lange ’18 MS (astrophysical sciences and technology), ’20 Ph.D. (astrophysical sciences and technology) worked on the parameter estimation part of the analysis, which identifies important characteristics about each gravitational wave event, including the masses of the black holes or neutron stars involved, their spin, distance from Earth and position in the sky. While he was a Ph.D. student at RIT, he helped develop parameter estimation algorithms that were faster than conventional methods and used for many of the events released in the catalog. Lange, who is now a postdoctoral researcher at Brown University’s Institute for Computational and Experimental Research in Mathematics, said that improvements to the sensors and parameter estimation techniques have yielded increasingly unique findings that challenge our understanding of the universe.

“We’re seeing much more complex events where nature’s really showing us its fascinating side,” said Lange. “We’ll be able to learn much more interesting physics and astrophysics from these detections. The more we build up this catalog of events, the more we can start making statements about the overall population.”

Daniel Wysocki ’18 MS (astrophysical sciences and technology), ’20 Ph.D. (astrophysical sciences and technology) worked on analyzing the population properties of black holes following O3a. Wysocki, now a postdoctoral researcher at University of Wisconsin-Milwaukee, said that we are gaining a clearer picture about what typical black holes look like, how many exist, how the population of black holes has changed as the universe evolved, and other important properties.

“This catalog represents a significant increase in sample size from our previous release,” said Wysocki. “It’s like a census that provides data for people to see if their physical models are consistent with what happens in the

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LIGO and Virgo reveal a huge collection of gravitational waves

Earth is awash in gravitational waves.

Over a six-month period, scientists captured a bounty of 39 sets of gravitational waves. The waves, which stretch and squeeze the fabric of spacetime, were caused by violent events such as the melding of two black holes into one.

The haul was reported by scientists with the LIGO and Virgo experiments in several studies posted October 28 on a collaboration website and at arXiv.org. The addition brings the tally of known gravitational wave events to 50.

The bevy of data, which includes sightings from April to October 2019, suggests that scientists’ gravitational wave–spotting skills have leveled up. Before this round of searching, only 11 events had been detected in the years since the effort began in 2015. Improvements to the detectors — two that make up the Advanced Laser Interferometer Gravitational-Wave Observatory, or LIGO, in the United States, and another, Virgo, in Italy — have dramatically boosted the rate of gravitational wave sightings.

While colliding black holes produced most of the ripples, a few collisions seem to have involved neutron stars, ultradense nuggets of matter left behind when stars explode.

Some of the events added to the gravitational wave register had been previously reported individually, including the biggest black hole collision spotted so far (SN: 9/2/20) and a collision between a black hole and an object that couldn’t be identified as either a neutron star or black hole (SN: 6/23/20).

Gravitational waves are produced when two massive objects, such as black holes, spiral around one another and merge. These visualizations, which are based on computer simulations, show these merging objects for 38 of the 50 known gravitational wave events.

What’s more, some of the coalescing black holes seem to be very large and spinning rapidly, says astrophysicist Richard O’Shaughnessy of the Rochester Institute of Technology in New York, a member of the LIGO collaboration. That’s something “really compelling in the data now that we hadn’t seen before,” he says. Such information might help reveal the processes by which black holes get partnered up before they collide (SN: 6/19/16).

Scientists also used the smorgasbord of smashups to further check Albert Einstein’s theory of gravity, general relativity, which predicts the existence of gravitational waves. When tested with the new data — surprise, surprise — Einstein came up a winner.

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