After a 10-month break, physicists are getting ready to catch gravitational waves again. The twin LIGO detectors have now been turned back on and they are in full science observation mode.
LIGO, which stands for Laser Interferometer Gravitational-wave Observatory, is responsible for the two gravitational wave discoveries we have had so far. The first one was announced last February, and it was between two very large black holes, which coalesced and culminated in the creation of a 60-solar mass black hole.
The second detection was announced last June, and it was between two more modest black holes that were eight and 14 times the mass of the Sun. Both detections were observed in 2015 when the two LIGO detectors were online.
“Researchers devoted more than 40 years to get to this point, and the National Science Foundation – I'm proud to say – was there all along the way, providing critical support to make this scientific achievement possible,” National Science Foundation Director France Córdova said in a statement. “Today, that journey continues. Already LIGO has exceeded our expectations, and, like most of the scientific world and beyond, I am excited to see what a more sensitive, upgraded LIGO will detect next.”
The detector that's located in Livingston, Louisiana, now has 25 percent more sensitivity than before, which will allow researchers to better understand how black holes interact with each other. The detector in Hanford, Washington, has the same sensitivity but with more power and improved stability, which reduces the noise in the signal and makes the detector operational for longer.
“LIGO's scientific and operational staff have been working hard for the past year and are enthusiastic to restart round-the-clock observations," said LIGO Livingston Observatory head Joe Giaime of Caltech and Louisiana State University in a statement. "We are as curious as the rest of the world about what nature will send our way this year."
Having two detectors allows researchers to make sure the detections are genuine. When the European detector Advanced Virgo comes online, scientists will be able to pinpoint the object's location in the sky and possibly detect some light counterpart to the gravitational-wave-producing event.
“The significance of this expanding 'window to the universe' cannot be stressed enough, as it will illuminate the physics of merging black holes, neutron stars and other astronomical phenomena that cannot be reproduced in a laboratory setting,” continued Córdova. “The world waits with eager anticipation of what we will see and learn next, all because of the long-range vision and skills of hundreds of researchers around the world.”