The Nobel Prize in Physics 2017 celebrates the direct detection of Gravitational waves arriving from the merger two large Black holes in a distant galaxy a Billion of light years away. The laureates are pioneers Rainer Weiss and Kip S Thorne, together with Barry C Barish, the scientist and leader who brought the project to completion, ensured that four decades of the effort led to gravitational waves finally being observed.
Gravitational waves carry information about their dramatic origins and about the nature of gravity that cannot otherwise be obtained. This opens a new window to Astronomy since Gravitational Waves are an entirely new way of observing the most violent events in space.
Perhaps, unprecedented is the level of Indian participation in this milestone discovery. The discovery paper has 39 authors from nine institutions – CMI Chennai, ICTS-TIFR Bengaluru, IISER-Kolkata, IISER-Trivandrum, IIT Gandhinagar, IPR Gandhinagar, IUCAA Pune, RRCAT Indore and TIFR Mumbai.
The current Indian gravitational wave scientific community has arisen out of research programmes carried out over three decades at several research institutes, with seminal contributions. The group led by Sanjeev Dhurandhar at IUCAA initiated and did foundational work on developing data-analysis techniques to detect these weak signals buried in the detector noise by looking for the best match between the calculated waveforms and the detector signal and led the solo Indian group in the LSC in the initial era of LIGO for a decade.
The group led by Bala Iyer (currently at ICTS-TIFR) at the Raman Research Institute in collaboration with scientists in France had pioneered the mathematical calculations used to model Gravitational Wave signals from orbiting black holes and neutron stars. Theoretical work that combined black holes and gravitational waves was published by C. V. Vishveshwara in 1970.
These contributions are prominently cited in the discovery paper.
An opportunity for India taking leadership in this field has opened up with the LIGO-India mega-science project that was granted ‘in principle’ approval by the Union Cabinet on Feb 17, 2016. LIGO-India brings forth a real possibility of Indian scientists and technologists stepping forward, with strong international cooperation, into the frontier of an emergent area of high visibility and promise presented by the recent GW detections and the high promise of a new window of gravitational-wave astronomy to probe the universe.
The global scientific community is unanimous that the future of Gravitational wave astronomy and astrophysics, beyond the first discovery, lies with the planned global array of GW detectors, including the LIGO-India observatory. The inclusion of LIGO-India greatly improves the angular resolution in the location of the gravitational-wave source by the LIGO global network. For the discovery event observed by the two advanced LIGO detectors in the US, with a hypothetical LIGO-India in operation, there would have been 100 times improvement in the angular resolution.
The LIGO-India proposal is for the construction and operation of an Advanced LIGO Detector in India in collaboration with the LIGO Laboratories, USA. The objective is to set up the Indian node of the three nodes global Advanced LIGO detector network by 2024 and operate it for 10 years. The task for LIGO-India includes the challenge of constructing the very large vacuum infrastructure that would hold a space of volume 10 million litres that can accommodate the entire 4 km scale laser interferometer in an ultra-high vacuum environment at nano-torrs. Indian team is also responsible for installation and commissioning the complex instrument and attaining the ultimate design sensitivity.
The LIGO-India project is being jointly executed by lead institutions: the Inter-University Centre for Astronomy and Astrophysics (IUCAA), Pune of the University Grants Commission, and DAE organisations, Institute for Plasma Research (IPR), Gandhinagar, the Raja Ramanna Centre for Advanced Technology (RRCAT), Indore and the Directorate of Construction & Estate Management (DCSEM) of DAE.
LIGO-India is being jointly funded by the Department of Atomic Energy (DAE) and the Department of Science and Technology (DST). A LIGO-India Apex committee, together with the LIGO-India Project Management Board (LI-PMB) and LIGO-India Scientific Management Board (LI-SMB), were constituted in August 2016 to oversee the project execution, and there has been rapid pace of progress since then. LIGO-India is on track for commencing operations by 2024.