India approves LIGO-India Laser Interferometer Gravitational wave detection project

The Indian government has given final approval to the "LIGO-India" project, which will build the world's third laser interferometer gravitational wave observatory. It will reportedly be a nearly identical version of the LIGO (Laser Interferometer Gravitational-Wave Observatory) facility that first directly detected gravitational waves in 2015. Going forward, the Indian government will spend 26 billion rupees (about US $320 million) to build LIGO-India, with the first observations expected by the end of 2030.

The "Ligo-India" project is a collaboration between the LIGO Laboratory (run by Caltech and MIT) and three institutes in India: One is located at the Raja Ramana Centre for Advanced Technology (RRCAT) in Indore, one at the Institute of Plasma Studies (IPR) in Ahmedabad, and one at the Inter-University Centre for Astronomy and Astrophysics (IUCAA) in Pune.

The proposed facility will be built near Aundha, in the Indian state of Maharashtra. Like the LIGO observatories in Hanford, Washington, and Livingston, Louisiana, it will include an "L" shaped interferometer with each arm measuring 4km. Two laser pulses are shot through each arm at the same time, and they bounce off the mirror at the end, returning to the apex. The detector checks if the pulses return at the same time.

(Photo credit: LIGO Caltech)

When LIGO-India is completed, it will join a global network of gravitational wave observatories including Virgo in Italy and KAGRA in Japan. With its advanced gravitational wave sensing technology, LIGO-India will greatly improve scientists' ability to pinpoint the source of gravitational waves. Because of its position on Earth relative to LIGO, Virgo, and KAGRA, it will also fill in the blind spots in the current gravitational wave network.

"LIGO-India will improve our accuracy in locating gravitational wave events by an expected order of magnitude," said Mr Adhikari. "This will greatly improve our ability to answer fundamental questions about the universe - including how black holes form, what is the expansion rate of the universe, and more rigorously test Einstein's general theory of relativity."

NSF Director Sethuraman Panchanathan said: "Ligo-india will enhance the existing network of gravitational wave detectors - the two LIGO detectors in the United States, Virgo detectors in Italy and KAGRA detectors in Japan - to be able to more precisely identify the location of gravitational wave sources and more reliable monitoring of their signals. This will give a huge boost to researchers around the world to combine observations from optical and radio telescopes with information from gravitational wave networks to make new discoveries about the universe."

The third LIGO detector has the same sensitivity as the two American detectors. The motivation for building the third LIGO interferometer is largely linked to building a larger global network of gravitational wave detectors. Such a global network of widely distributed facilities is needed to extract the best information from gravitational waves. Specifically, adding more detectors to the network could improve the ability to locate sources, test theories of gravity, space and time, and provide important clues to astrophysical and cosmological puzzles.

Although having two detectors in a network (such as Virgo in Louisiana, USA) could improve the polarization information extracted from the waves and the source location. But even a network of three observatories would only provide a clear sky position for about half of the possible locations in the sky.

The scientists' ultimate goal is to locate sources of gravitational waves anywhere in the sky. To do so would require running four similar probes simultaneously around the globe. Of course, given the complexity of gravitational wave detectors, to increase the odds that all four will operate at the same time, a fourth detector (Kagra in Japan) will be operational next year. LIGO-India will be the most important fifth. When it is up and running, LIGO-India will greatly improve the possibility of running four detectors at any given moment. This is the key role LIGO-India will play in the global network of gravitational wave detectors.

Both the LIGO Laboratory and India have made significant financial and intellectual contributions to the project:

The LIGO Laboratory provides complete hardware for LIGO interferometers, technical data on design, installation and commissioning, training and assistance in installation and commissioning, and requirements and design of the necessary infrastructure, including vacuum systems.

India is providing the site, vacuum system and other infrastructure to house and operate the interferometer, as well as all Labour, materials and supplies required for installation, commissioning and operation. Funding for the LIGO-India facility came from the Department of Atomic Energy (DAE) and the Department of Science and Technology (DST) of India, with DAE being the lead agency.

Once operational, Ligo-India will collaborate with the US LIGO detectors for scientific management and operation to optimize the scientific returns of this project.

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

Rana Adhikari, professor of physics at the California Institute of Technology, said: "As the latest gravitational wave detector, LIGO-india will integrate all of our latest and greatest technology from the very beginning." Rana Adhikari, along with Reitze and other members of the LIGO team, collaborated with Indian scientists and helped lead the development of Ligo-India.

Source: OFweek