Laser Interferometer Gravitational-wave Observatory (LIGO) scientists have made dozens of trips to India to work with Indian colleagues, especially with the three nodal institutes that would have primary responsibility for construction and operation of LIGO India — Institute of Plasma Research (IPR) Gandhinagar, Inter University Centre for Astronomy and Astrophysics (IUCAA), Pune, and Raja Ramanna Centre for Advanced Technology (RRCAT), Indore.
With the Indian government giving in-principle approval for establishing a state-of-the-art LIGO interferometer in the country, a top US scientist has said it is “technically feasible” for the project to be operational by the end of 2023.
“It is technically feasible for LIGO-India to go online by the end of 2023,” said Fred Raab, head of the LIGO Hanford Observatory and LIGO Laboratory liaison for LIGO-India.
Laser Interferometer Gravitational-wave Observatory (LIGO) scientists have made dozens of trips to India to work with Indian colleagues, especially with the three nodal institutes that would have primary responsibility for construction and operation of LIGO India — Institute of Plasma Research (IPR) Gandhinagar, Inter University Centre for Astronomy and Astrophysics (IUCAA), Pune, and Raja Ramanna Centre for Advanced Technology (RRCAT), Indore. “Together, we have identified an excellent site for the facilities and have transferred detailed LIGO drawings of the facilities and vacuum system to IPR, after adapting them for conditions in India,” he said.
The Union Cabinet on February 17, gave its approval in the wake of the announcement of LIGO’s detection of gravitational waves earlier this month. “This is the step that we’ve been waiting for. It will allow funding for the LIGO-India project to begin, and commence a number of critical path activities toward getting a detector built in India,” said LIGO Laboratory Executive Director David Reitze. “Coming on the heels of the Discovery announcement, this has truly been an historic week for LIGO and for the field of gravitational wave astronomy,” he said.
The project will build an Advanced LIGO Observatory in India, a move that will significantly improve the ability of scientists to pinpoint the sources of gravitational waves and analyze the signals, a statement said. Gravitational waves—ripples in the fabric of space and time, produced by dramatic events in the universe such as merging black holes and predicted as a consequence of Albert Einstein’s 1915 general theory of relativity, carry information about their origins and about the nature of gravity that cannot otherwise be obtained. With their first direct detection, announced on February 11, scientists opened a new window onto the cosmos.
The twin LIGO Observatories at Hanford, Washington, and Livingston, Louisiana, are funded by the US National Science Foundation (NSF), and were conceived, built, and are operated by Caltech and MIT. Advanced LIGO — a major upgrade to the sensitivity of the instruments compared to the first generation LIGO detectors — began scientific operations in September 2015. Funded in large part by the NSF, Advanced LIGO enabled a large increase in the volume of the universe probed, leading to the discovery of gravitational waves during its first observation run. At each observatory, the 4-km-long L-shaped interferometer uses laser light split into two beams that travel back and forth down the arms (four-foot diameter tubes kept under a near-perfect vacuum). The beams are used to monitor the distance between mirrors precisely positioned at the ends of the arms.
According to Einstein’s theory, the distance between the mirrors will change by an infinitesimal amount when a gravitational wave passes by the detector. A change in the lengths of the arms smaller than one-ten-thousandth the diameter of a proton (10-19 metre) can be detected. According to Reitze, the executive director of LIGO and a Caltech research professor, the degree of precision achieved by Advanced LIGO is analogous to being able to measure the distance between our solar system and the sun’s nearest neighbour Alpha Centauri — about 4.4 light-years away, accurately to within a few microns, a tiny fraction of the diametre of a human hair. “We have built an exact copy of that instrument that can be used in the LIGO-India Observatory,” said David Shoemaker, leader of the Advanced LIGO Project and director of the MIT LIGO Lab, “ensuring that the new detector can both quickly come up to speed and match the US detector performance”.
LIGO will provide Indian researchers with the components and training to build and run the new Advanced LIGO detector, which will then be operated by the Indian team, the statement said. LIGO-India will also bring considerable opportunities in cutting edge technology for the Indian industry which will be engaged in the construction of the new observatory’s 4-kilometer-long beam tubes. As per the US statement, Indian scientists at RRCAT have designed a special testing/prototype facility for receiving Advanced LIGO parts, have been training the teams that will install and commission the detector and are currently cross-checking the IPR vacuum system drawings against the Advanced LIGO detector drawings to ensure a good fit and rapid installation for the third Advanced LIGO detector. In addition to leading the site-selection process, IUCAA scientists have been setting up a computing centre for current and future data. This preparation should make it possible for India to carry the project forward rapidly, it noted. “LIGO-India will further expand the international network that started with the partnership between LIGO and Virgo, which operates a detector near Pisa, Italy,” said Stanley Whitcomb, LIGO chief scientist. “With LIGO-India added to the network, we will not only detect more sources, we will dramatically increase the number of sources that can be pinpointed so that they can be studied using other types of telescopes,” he said.