LIGO (Laser Interferometer Gravitational-Wave Observatory)

A gravitational wave observatory has been set up in India in collaboration with LIGO. This project is expected to join the international network in a first science run in 2025.

What is LIGO?

• It is the world's largest gravitational wave observatory and a wonder of precision engineering.
• It comprises of two enormous laser interferometers located thousands of kilometres apart, each having two arms which are 4 km long.
• It exploits the physical properties of light and of space itself to detect and understand the origins of Gravitational Waves (GW).

Sources of GW

• Mergers of black holes or neutron stars, rapidly rotating neutron stars, supernova explosions and the remnants of the disturbance caused by the formation of the universe, the Big Bang itself, are the strongest sources.
• There can be many other sources, but these are likely to be too weak to detect.
• The study of GW offers a new way to map out the universe by using gravitational-wave astronomy.

LIGO detectors

• Two LIGO detectors work as one unit to ensure a remarkable precision, which is needed to detect a signal as weak as a gravitational wave.
• Its detector components are completely isolated and sheltered from the outside world.
• Unlike optical or radio telescopes, it does not see electromagnetic radiation (e.g., visible light, radio waves and microwaves) because gravitational waves are not part of the electromagnetic spectrum.
• It doesn’t need to collect light from stars; it doesn't need to be round or dish-shaped like optical telescope mirrors or radio telescope dishes, both of which focus EM radiation to produce images.

LIGO Project at a global level

• Two LIGO detectors are already operational in the U.S., at Livingston and Hanford.
• The Japanese detector, KAGRA, or Kamioka Gravitational-wave Detector, is expected to join the international network soon.

LIGO India

• LIGO India will come up in Maharashtra, which will also have two arms of 4 km length.
• The project aims to move one Advanced LIGO detector from Hanford to India.
• This project is a collaboration between the LIGO Laboratory 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.
• It is an ultra-high precision large-scale apparatus, which is expected to show a unique “temperament” determined by the local site characteristics.

Significance of another detector in India

• To locate gravitational waves: Observations from a new detector in a far-off position will help locate the source of the gravitational waves more accurately.
• Identification of new sources: Nnew detector will increase the expected event rates, and will boost the detection confidence of new sources (by increasing the sensitivity, sky coverage and duty cycle of the network).
• Impact on Indian Science: The project will help Indian scientific community to be a major player in the emerging research frontier of GW astronomy. This major initiative will further inspire frontier research and development projects in India.
• Impact on industry: The high-end engineering requirements of the project (such as the world's largest ultra-high vacuum facility) will provide unprecedented opportunities for Indian industries in collaboration with academic research institutions.
• Education and public outreach: A cutting edge project in India can serve as a local focus to interest and inspire students and young scientists. The project involves high technology instrumentation and its dramatic scale will spur interest and provide motivation to young students for choosing experimental physics and engineering physics as career options.

What is the technology being developed in India for LIGO India?

• Some of it includes design and fabrication of ultra-stable laser, quantum measurement techniques, handling of complex control system for enforcing precision control, large-scale ultra-high vacuum technology, data analysis and machine learning.
• This is not a complete list and the development of such indigenous technology is likely to result in many spin-offs for industry and research.
• The dramatic improvement from LIGO-India would come in the ability of localizing GW sources in the sky.

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