30-Mar-2022: Funding for LIGO-India Project

Union Minister of State (Independent Charge) Science & Technology; Minister of State (Independent Charge) Earth Sciences; MoS PMO, Personnel, Public Grievances, Pensions, Atomic Energy and Space, Dr Jitendra Singh said that Government of India accorded In-principle approval for Laser Interferometer Gravitational wave Observatory (LIGO)-India project at an estimated cost of Rs. 1260 crore.

In a written reply to a question in the Lok Sabha today, Dr Jitendra Singh said, subsequent to the In-principle approval, Department of Atomic Energy sanctioned Rs. 75 crore for pre-investment activities.

The Minister informed that India partners with the United States of America (USA) under a Memorandum of Understanding signed between Department of Atomic Energy & Department of Science & Technology and National Science Foundation of USA to set up a LIGO Detector in India as part of a Global Network of Gravitational Wave Detectors under the LIGO-India Project.

25-Apr-2020: First merger of two black holes with unequal masses detected

For the first time since it started functioning, the gravitational wave observatories at LIGO scientific collaboration have detected a merger of two unequal-mass black holes. The event, dubbed GW190412, was detected nearly a year ago, and this is almost five years after the first ever detection of gravitational wave signals by these powerful detectors. Subsequent analysis of the signal coming from the violent merger showed that it involved two black holes of unequal masses coalescing, one of which was some 30 times the mass of the Sun and the other which had a mass nearly 8 times the solar mass. The actual merger took place at a distance of 2.5 billion light years away. This study has been published in preprint server ArXiv, and is pending peer review.

The detected signal’s waveform has special extra features in it when it corresponds to the merger of two unequal-sized black holes as compared with a merger of equal-sized black holes. These features make it possible to infer many more things about the characters in this celestial drama, namely, a more accurate determination of the distance from the event, the spin or angular momentum of the more massive black hole and the orientation of the whole event with respect to viewers on Earth.

While the mass of the black hole bends the space-time close to it, the spin or angular momentum of this inscrutable object drags the nearby space-time, causing it to swirl around, along with it. Hence both these properties are important to estimate.

Dominant emission of gravitational waves happens at twice the orbital frequency of the binary. In this case, we find, for the first time, emission at a frequency that is three times the orbital frequency. This emission is negligible when binaries contain equal masses and when the orbit is face-on. GR has a unique prediction for the details of this emission which is verified by this observation.

A second Indian team consisting of researchers from ICTS-TIFR, Bengaluru, verified the consistency of the signal with the prediction of General Relativity.

The existence of higher harmonics was itself a prediction of General Relativity.

6-Jan-2020: LIGO-Virgo Network Catches Another Neutron Star Collision

On April 25, 2019, the LIGO Livingston Observatory picked up what appeared to be gravitational ripples from a collision of two neutron stars. LIGO Livingston is part of a gravitational-wave network that includes LIGO (the Laser Interferometer Gravitational-wave Observatory), funded by the National Science Foundation (NSF), and the European Virgo detector. Now, a new study confirms that this event was indeed likely the result of a merger of two neutron stars. This would be only the second time this type of event has ever been observed in gravitational waves.

The first such observation, which took place in August of 2017, made history for being the first time that both gravitational waves and light were detected from the same cosmic event. The April 25 merger, by contrast, did not result in any light being detected. However, through an analysis of the gravitational-wave data alone, researchers have learned that the collision produced an object with an unusually high mass.

From conventional observations with light, we already knew of 17 binary neutron star systems in our own galaxy and we have estimated the masses of these stars. What's surprising is that the combined mass of this binary is much higher than what was expected.

We have detected a second event consistent with a binary neutron star system and this is an important confirmation of the August 2017 event that marked an exciting new beginning for multi-messenger astronomy two years ago. Multi-messenger astronomy occurs when different types of signals are witnessed simultaneously, such as those based on gravitational waves and light.

Neutron stars are the remnants of dying stars that undergo catastrophic explosions as they collapse at the end of their lives. When two neutron stars spiral together, they undergo a violent merger that sends gravitational shudders through the fabric of space and time.

LIGO became the first observatory to directly detect gravitational waves in 2015; in that instance, the waves were generated by the fierce collision of two black holes. Since then, LIGO and Virgo have registered dozens of additional candidate black hole mergers.

The August 2017 neutron star merger was witnessed by both LIGO detectors, one in Livingston, Louisiana, and one in Hanford, Washington, together with a host of light-based telescopes around the world (neutron star collisions produce light, while black hole collisions are generally thought not to do so). This merger was not clearly visible in the Virgo data, but that fact provided key information that ultimately pinpointed the event’s location in the sky.

The April 2019 event was first identified in data from the LIGO Livingston detector alone. The LIGO Hanford detector was temporarily offline at the time, and, at a distance of more than 500 million light-years, the event was too faint to be visible in Virgo's data. Using the Livingston data, combined with information derived from Virgo’s data, the team narrowed the location of the event to a patch of sky more than 8,200 square degrees in size, or about 20 percent of the sky. For comparison, the August 2017 event was narrowed to a region of just 16 square degrees, or 0.04 percent of the sky.

The LIGO data reveal that the combined mass of the merged bodies is about 3.4 times the mass of our sun. In our galaxy, known binary neutron star systems have combined masses up to only 2.9 times that of sun. One possibility for the unusually high mass is that the collision took place not between two neutron stars, but a neutron star and a black hole, since black holes are heavier than neutron stars. But if this were the case, the black hole would have to be exceptionally small for its class. Instead, the scientists believe it is much more likely that LIGO witnessed a shattering of two neutron stars.

What we know from the data are the masses, and the individual masses most likely correspond to neutron stars. However, as a binary neutron star system, the total mass is much higher than any of the other known galactic neutron star binaries. And this could have interesting implications for how the pair originally formed.

Neutron star pairs are thought to form in two possible ways. They might form from binary systems of massive stars that each end their lives as neutron stars, or they might arise when two separately formed neutron stars come together within a dense stellar environment. The LIGO data for the April 25 event do not indicate which of these scenarios is more likely, but they do suggest that more data and new models are needed to explain the merger’s unexpectedly high mass.

16-Aug-2018: Scientists to test land for LIGO

The Environment Ministry has allowed scientists to test the suitability of land in Maharashtra’s Hingoli district to host the India wing of the ambitious Laser Interferometer Gravitational Wave Observatory (LIGO) project. This is a key step to establishing the one-of-its-kind astronomical observatory.

The project involves constructing a network of L-shaped arms, each four kilometres long, which can detect even the faintest ripples from cosmic explosions millions of light years away.

The discovery of gravitational waves earned three U.S. scientists the Nobel for physics in 2017. The scientists were closely involved with LIGO. Hosting such a detector in India, scientists have said, will improve the odds of detecting more such phenomena.

However the construction of such a large, sensitive device — there are only three of its kind in the world — requires an extremely flat surface.

The LIGO-India consortium, made up of physicists from several institutes, had submitted a proposal to “prospect” 121 hectares of forest land in Dudhala village, Hingoli.

Typically, mining companies prospect a region by sinking boreholes to get a sense of the geology of the site and ascertain availability of required minerals and metals. In the case of the LIGO project, it is to check if the land can be made perfectly level at a reasonable cost. The consortium is yet to formally declare the Dudhala site as the host of the interferometers.

The prospecting permission, according to the minutes of the forest clearance committee meeting of the Union Environment Ministry, was only for sinking boreholes in 0.375 hectares and separate permission would be needed at a later stage for constructing the observatory.

Network of detectors: The LIGO project operates three gravitational-wave (GW) detectors. Two are at Hanford in the State of Washington, north-western USA, and one is at Livingston in Louisiana, south-eastern USA. Currently these observatories are being upgraded to their advanced configurations.

The proposed LIGO-India project aims to move one Advanced LIGO detector from Hanford to India. The LIGO-India project is an international collaboration between the LIGO Laboratory and three lead institutions in the LIGO-India consortium: Institute of Plasma Research, Gandhinagar; IUCAA, Pune; and Raja Ramanna Centre for Advanced Technology, Indore. The LIGO lab would provide the complete design and all the key detector components. Indian scientists would provide the infrastructure to install the detector and it would be operated jointly by LIGO-India and the LIGO-Lab.

The project, piloted by the Department of Atomic Energy (DAE) and Department of Science and Technology (DST), reportedly costs ₹1,200 crore and is expected to be ready by 2025.

17-Jan-2017: LIGO India will be functional by 2024.

The LIGO India project is likely to be commissioned in 2024. The LIGO India centre, which will study cosmic gravitational waves, will be the third one in the world.

The LIGO (Laser Interferometer Gravitational-wave Observatory) is a massive observatory for detecting cosmic gravitational waves and for carrying out experiments. The objective is to use gravitational-wave observations in astronomical studies.

It would require Indian universities to churn out young researchers trained in the science, according to the announcement made by LIGO Laboratory.

We hope by 2024 a crew of Indian PhDs trained in the science (astrophysics) will be commissioning those machines and beginning first observations.

The project operates three gravitational-wave (GW) detectors. Two are at Hanford in the state of Washington, north-western US, and one is at Livingston in Louisiana, south-eastern US.

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

The effect will be dramatic because it will give us tremendous location information on where the (gravitational waves) sources are. You turn on the detector in India and everywhere in the sky you can pinpoint the sources much better.

However, to what extent the activities succeed depends on availability of trained scientists.