Context: 

In a major breakthrough, an international team of astronomers announced scientific evidence confirming the presence of gravitational waves using pulsar observations.

• India’s Giant Metrewave Radio Telescope (GMRT) was among the world’s six large telescopes that played a vital role in providing evidence confirming the presence of gravitational waves.

Image Source: Hindustan times

About Pulsars:

• Pulsars are rapidly rotating neutron stars that blast out pulses of radiation at regular intervals ranging from seconds to milliseconds.
• A pulsar is like a cosmic lighthouse as it emits radio beams that flashes by the Earth regularly akin to a harbour lighthouse.

Gravitational Waves:

• Gravitational waves are ripples, or disturbances, produced in the fabric of spacetime by large moving objects, something similar to the ripples produced on the surface of water by a moving boat. 
• Prediction: The existence of gravitational waves was predicted by Albert Einstein’s general theory of relativity more than a century ago, but its experimental confirmation came only in 2015.
• Sources: Through collision of pairs of very large, ‘monster’, black holes, millions of times bigger than our Sun. Such large blackholes are usually found at the centres of galaxies. 
• Characteristics: Gravitational waves originating from the collision or mergers of such blackholes can have very large wavelengths, extending up to light years, and consequently, very low frequencies.

Giant Metrewave Radio Telescope (GMRT):

• GMRT is a low-frequency radio telescope that helps investigate various radio astrophysical problems ranging from nearby solar systems to the edge of the observable universe. 
• Nodal Agency: It is a project of the Department of Atomic Energy (DAE), operating under the Tata Institute of Fundamental Research (TIFR). 
• Frequency: 
  1. GMRT is a unique facility functioning within the frequency bandwidth of 100 Mhz-1,500 MHz. 
  2. The GMRT enjoys special protection for carrying out its sensitive observations in the above frequency range.
• Number of telescopes: It is an array of thirty fully steerable parabolic radio telescopes of 45 metre diameter.

Recent Findings of GMRT:

• An international team of astronomers from India, Japan and Europe has published the results from monitoring pulsars, called ‘nature’s best clocks’, by using six of the world’s most sensitive radio telescopes, including India’s largest telescope, the Pune based GMRT. 
• These results provide a hint of evidence for the relentless vibrations of the fabric of the universe, caused by ultra low frequency gravitational waves.
• In order to detect gravitational wave signals, scientists explore several ultra­stable pulsar clocks randomly distributed across our Milky Way galaxy and create an imaginary galactic scale gravitational wave detector.
• Presence of gravitational waves: These telescopes measured very small delays (millionths of a second) in the signals coming from rapidly rotating stars called pulsars. 
  • Scientists propose that these delays were a result of deformities caused in space-time by gravitational waves.
  • These irregularities showed consistent effects of the presence of gravitational waves.

News Source: The Hindu