doi:10.1038/nindia.2016.20 Published online 11 February 2016

Gravitational waves send ripples of joy for LIGO-India

Subhra Priyadarshini

As the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) made the big announcement on spotting the elusive gravitational waves in Washington, Indian scientists were ecstatic at the prospect of an advanced gravitational-wave detector being operational in India soon.

A group of gravitational wave scientists at IUCAA, Pune
© Tarun Souradeep
Minutes after Gabriela González, spokesperson for the LIGO Scientific Collaboration and a research scientist at the Louisiana State University announced that LIGO-India could be a possibility soon, India's Prime Minister Narendra Modi tweeted, "Hope to move forward to make even bigger contribution with an advanced gravitational wave detector in the country." 

This was instantly greeted by a loud and long applause at the Inter-University Council of Astronomy and Astrophysics (IUCAA) in Pune, where India's leading astrophysicists and many scientists involved in the global project had gathered.

If all goes well, the multi-institutional Indian project in gravitational-wave astronomy could start functioning by 2020. India is expected to provide the site, the vacuum system and other infrastructure required to house and operate the interferometer, and all labour, materials and supplies for installation, commissioning and operations. Funding for the over Rs 1200 crore LIGO-India facilities will come from India's Department of Atomic Energy (DAE) and the Department of Science and Technology (DST).

Once it becomes operational, LIGO-India is expected to be scientifically managed and operated in collaboration with the US LIGO detectors to optimize the scientific return.

Advanced LIGO operates three gravitational-wave (GW) detectors — two at Hanford in Washington, and one in Livingston in Louisiana, USA. The proposed LIGO-India project aims to move one Advanced LIGO detector from Hanford to India.

The proposed LIGO-India project aims to move one Advanced LIGO detector from Hanford to India.

© Tarun Souradeep
India has made significant contributions to the international effort for detecting GWs on two fronts — in source modeling under Bala Iyer at the Raman Research Institute (RRI) and in data analysis at IUCAA under Sanjeev Dhurandhar. Dhurandhar, who has been working in this field since 1989 said he was "Overwhelmed, twice!" at the indication that the LIGO-India project might realise its dreams soon. The group at RRI was part of an Indo-French collaboration for two decades to compute high accuracy waveforms for in-spiraling compact binaries from which the GW templates used in LIGO and the Italian project Virgo are constructed. Theoretical work that combined black holes and gravitational waves was published by C. V. Vishveshwara in 1970.

The international consortium has 61 Indian scientists from nine institutions: CMI Chennai, ICTS­TIFR Bengaluru, IISER ­Kolkata, IISER ­Trivandrum, IIT Gandhinagar, IPR Gandhinagar, IUCAA Pune, RRCAT Indore and TIFR Mumbai.The discovery paper published today has 35 authors from these institutions.

The LIGO-India project

The LIGO-India project is an international collaboration between LIGO and three lead institutions in the IndIGO consortium: Institute of Plasma Research (IPR) Gandhinagar, Inter University Centre for Astronomy and Astrophysics (IUCAA), Pune and Raja Ramanna Centre for Advanced Technology (RRCAT), Indore. LIGO would provide the design and all the key detector components.

Indian scientists would provide the infrastructure to install the detector at a suitable site in India and would be responsible for commissioning it, according to spokesperson of the Indian Initiative in Gravitational-wave Observations (IndIGO) Tarun Souradeep Ghosh. India participates in the international consortium under the IndIGO umbrella formed in 2009 by a group of researchers with expertise in theoretical and experimental gravity, cosmology and optical metrology, who were keen to promote gravitational wave research in the country with a dream of realising an advanced detector in India. "Hope floats for something I have been passionately pursuing for over 5 years now," Ghosh posted on Facebook following Modi's praise for the Indian scientists on Twitter.

The proposed observatory would be operated jointly by IndIGO and LIGO and would form a single network along with the LIGO detectors in USA and Virgo in Italy. The design of the proposed detector would be identical to that of the Advanced LIGO detectors in the USA.

Adding a new detector to the existing network will increase the expected event rates, and will boost the detection confidence of new sources. LIGO-India sources say the dramatic improvement, however, would come in the ability of localising GW sources in the sky. IUCAA Director Somak Raychaudhury said detectors from many more directions would be able to provide better observations. "The discovery paves the road to the possibility of observing our universe in gravitational waves if one can locate their source with additional detectors placed far from the LIGO detectors, forming one or more large triangles," he said.

Adding a new detector in India, geographically well separated from the existing LIGO-Virgo detector array, will dramatically improve the source-localization accuracies (5 to 10 times), enabling scientists to use GW observations as an excellent astronomical tool, according to LIGO-India sources. The proposed LIGO-India project will help Indian scientific community to be a major player in the emerging research frontier of GW astronomy.

The multidisciplinary project is expected bring together scientists and engineers from different fields like optics, lasers, gravitational physics, astronomy and astrophysics, cosmology, computational science, mathematics and various branches of engineering. 

In order to fully realise the potential of multi-messenger astronomy, the LIGO-India project will join forces with several Indian astronomy projects. Potential collaborators of the project include the Astrosat project, future upgrades of the India-based Neutrino Observatory and optical/radio telescopes, the sources added.