LIGO resumes hunt for gravitational waves after receiving upgrades

The Laser Interferometer Gravitational-wave Observatory (LIGO) has resumed scientific operations after a series of engineering test runs. The LIGO observatories look for ripples in the space-time continuum, known as gravitational waves. There are two LIGO detectors, one in Livingston and one in Hanford. The sensitivity of the Livingston detector has been improved by twenty five percent, by reducing the level of scattered light. The Hanford detector is as sensitive as it was before.

Peter Fritschel, LIGO’s chief detector scientist, said “The Livingston detector has improved sensitivity for lower gravitational-wave frequencies, below about 100 hertz, primarily as the result of reducing the level of scattered light, which can be a pernicious source of noise in the interferometers.”

In February this year, LIGO first detected gravitational waves, a landmark scientific discovery proving Einstein’s hypothesis of the existence of such waves. The waves were caused by the collision of two black holes 1.3 billion light years away. A second instance of detection originated from another collision of black holes. The two observations were made between September 2015 and January 2016. After the detection, scientists upgraded the optics, lasers and electronics, making the instruments more sensitive. This is a simulation of what a pair of merging black holes looks like.

Dave Reitze, executive director of the LIGO Laboratory said “For our first run, we made two confirmed detections of black-hole mergers in four months. With our improved sensitivity, and a longer observing period, we will likely observe even more black-hole mergers in the coming run and further enhance our knowledge of black-hole dynamics. We are only just now, thanks to LIGO, learning about how often events like these occur.”

There are plans to upgrade the facilities after scientific observational runs, to continuously improve the observatories, and allow for detection of gravitational waves from larger distances. Apart from black hole mergers, LIGO may also be able to detect mergers between Neutron Stars. Data on the number of these events, the masses and spin rates of the bodies involved, will help scientists get a clearer picture of stellar evolution.

Two top US tech institutes, MIT and Caltech have collaborated to build LIGO. The Caltech press release for the resumed scientific operations can be found here. MIT has put up an interview with Peter Fritschel. A third LIGO observatory, the first one outside the US, and one with detection capabilities more advanced than the US counterparts, is planned to be built in India. Aundh in Hingoli, Maharashtra, has been selected as the site of this third LIGO facility.