A rendering of the LIGO-India site in the state of Maharashtra.

India greenlights gravitational-wave observatory project

Image credit: LIGO-India

The Indian government has granted the final approvals needed to begin the construction of the LIGO (Laser Interferometer Gravitational-Wave Observatory) in the country.

Indian Prime Minister Shri Narendra Modi has approved 26 billion rupees (£353m) for the construction of LIGO-India, expected to be completed by 2030. 

The facility has been designed as an exact copy of the twin gravitational wave observatories located in Hanford, Washington, and Livingston, Louisiana. The observatory is the fifth facility to join a global network of observatories focusing on detecting disturbances in space-time, known as gravitational waves.

LIGO-India will be built near the city of Aundha in the Indian state of Maharashtra.

"In a nutshell, it will add to our astronomical capabilities and will enable us to offer inputs and feedback not only to India but to rest of the world," Indian union minister Shri Jitendra Singh said at a briefing. 

The process that guided the moving and merging of massive objects in space was first explained by Albert Einstein more than a hundred years ago as the probable cause of gravitational waves. These disturbances, however, are so small that extremely sophisticated technologies are needed to detect them. 

These ripples in space-time were detected for the first time in September 2015 by LIGO. Since then, LIGO has captured three more signals of gravitational waves: one in 2016 and two in 2017.

"We've worked very hard over the past few years to bring a LIGO detector to India," said David Reitze, the executive director of the LIGO Laboratory at Caltech. "Receiving the green light from the Indian government is a very welcome development that will benefit not only India but the entire international gravitational-wave community."

LIGO-India is expected to greatly improve the ability of scientists to pinpoint the sky locations of the sources of gravitational waves.

Once it is completed, the observatory will be able to fill in blind spots in the current gravitational-wave network. This network is currently made up of the two LIGO observatories in the US, in addition to Virgo in Italy and KAGRA in Japan.

"As the newest gravitational-wave detector, LIGO-India will have all of our latest and best techniques incorporated from the get-go," said Rana Adhikari, a professor of physics at Caltech who helps lead the development of LIGO-India.

"LIGO-India will increase the precision with which we can localise the gravitational-wave events by an order of magnitude. This will greatly enhance our ability to answer fundamental questions about the universe, including how black holes form and the expansion rate of our universe, as well as to more rigorously test Einstein's general theory of relativity."

LIGO-India, first approved in 2016, is a joint effort among three Indian research institutes and the California Institute of Technology (Caltech) and the Massachusetts Institute of Technology (MIT), which together operate the US-based LIGO detectors. 

Some preconstruction activities for LIGO-India have already taken place, such as the design of the LIGO-India buildings, the construction of the roads that lead into the site, and the fabrication and testing of vacuum chambers. The facility will be built by Indian researchers working jointly with members of the LIGO team.

"Having a distant third LIGO observatory in the international network, which benefits from common instrument designs, commissioning knowledge, technical coordination, and sensitivity, will fulfil a longstanding LIGO goal," says Fred Raab, former associate director for observatory operations at LIGO Hanford. "This will be a game-changer for science."

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