The discovery announced on Tuesday is the latest success, and one of the biggest, for the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO). The events reported today include the biggest-known such merger.
A team of scientists have detected the gravitational waves that resulted from the biggest collision of black holes ever observed and which formed a new black hole about 80 times larger than the sun. While they can be produced on a small scale, our current detection facilities, like the huge LIGO detector, are capable of detecting large events.
The binary systems, meaning two black holes orbiting each other, eventually smash together and radiate strong gravitational waves which are very faint by the time they reach earth, said Professor Scott, from the Australian Research Council Centre of Excellence for Gravitational Wave Discovery (OzGrav).
The researchers detected the collisions after re-analyzing the gravitational wave data obtained by the LIGO.
You can read about what happens to the colliding black holes more generally in the article linked below, but in short, they combine into a bigger black hole and release excess mass as energy that travels as gravitational waves. One is titled "GWTC-1: A Gravitational-Wave Transient Catalog of Compact Binary Mergers Observed by LIGO and Virgo during the First and Second Observing Runs". "We've been sifting through the data, looking at every feature, comparing it to our astrophysical predictions, cross-checking it against monitors that tell us the health of the instruments, determining if it appears in all the detectors, and using our most robust (but slow-running) super-computer analysis codes", Shane Larsen, a Northwestern University physicist and member of the LIGO collaboration, wrote on the Write Science blog.
"This event also had black holes spinning the fastest of all mergers observed so far".
"The next observing run, starting in Spring 2019, should yield many more gravitational-wave candidates, and the science the community can accomplish will grow accordingly", says David Shoemaker, spokesperson for the LIGO Scientific Collaboration and senior research scientist in MIT's Kavli Institute for Astrophysics and Space Research. "It's an incredibly exciting time".
Gravitational waves are considered ripples in this fabric.
"The new catalog is another proof of the exemplary global collaboration of the gravitational wave community and an asset for the forthcoming runs and upgrades" adds EGO Director Stavros Katsanevas.
The scientific papers describing the findings, which are being initially published on the arXiv repository of electronic preprints, present detailed information in the form of a catalogue of all the gravitational wave detections and candidate events of the two observing runs. Among the things scientists have learned so far: all stellar black holes were formed from stars 45 times less than the mass of our Sun.
If the new events are from the same second runs as events previously reported, why are we only hearing about them now?
LIGO is funded by NSF and operated by Caltech and MIT, which conceived of LIGO and led the Initial and Advanced LIGO projects.
LIGO consists of two L-shaped, 2.5-mile-long detectors.