LIGO back online, set to detect more gravitational waves

Boston, December 5

The twin detectors of LIGO — which made the first ever direct detection of gravitational waves — have been restarted and scientists expect to detect more black hole mergers from farther out in the universe.

Researchers have made enhancements to LIGO’s lasers, electronics, and optics and have increased the observatory’s sensitivity by 10 to 25 per cent.

The detectors will now be able to tune in to gravitational waves - and the extreme events from which they arise - that emanate from farther out in the universe, scientists said.

On September 14 last year, the Laser Interferometer Gravitational-wave Observatory (LIGO)’s detectors detected gravitational waves for the first time, just two days after it was restarted as Advanced LIGO - an upgraded version of LIGO’s two large interferometers, placed 3,000 kilometres apart from each other.

After analysing the signal, scientists determined that it was indeed a gravitational wave, which arose from the merger of two massive black holes 1.3 billion light years away.

Three months later, on December 26, the detectors picked up another signal, which scientists decoded as a second gravitational wave, rippling out from yet another black hole merger, slightly farther out in the universe, 1.4 billion light years away.

With LIGO’s latest upgrades, researchers are hoping to detect more frequent signals of gravitational waves, arising from colliding black holes and other extreme cosmic phenomena.

One of the LIGO’s two large interferometers is located in Washington, and the other 3,000 kilometres away in Lousiana.

The Lousiana detector is now sensitive enough to detect a merger from as far away as 660 million light years. This is about 25 per cent farther than it could ‘see’ in the first observing run, said Peter Fritschel, LIGO’s chief detector scientist.

For the Washington detector the corresponding sensitivity range is pretty much on par with what it was during the first run and is about 15 per cent lower than these figures, said Fritschel. — PTI