India's Largest Radio Telescope Key to Detecting the Universe's Vibrations
The universe is not silent. It is constantly humming with vibrations caused by gravitational waves, ripples in the fabric of space-time that are produced by massive events such as collisions of black holes or neutron stars. These waves carry information about the origin and evolution of the cosmos, but they are extremely hard to detect because they are very weak and have very low frequencies.
However, a team of international scientists, including some from India, has made a breakthrough in finding the first direct evidence for these ultra-low frequency gravitational waves. They used six of the world's largest radio telescopes, including India's Giant Metrewave Radio Telescope (GMRT), to monitor pulsars, which are rapidly spinning neutron stars that act like cosmic clocks. By measuring the tiny changes in the arrival times of the radio pulses from these pulsars, the scientists were able to detect the subtle effects of the gravitational waves on the space-time between the Earth and the pulsars.
The GMRT, located near Narayangaon, Pune, is an array of thirty fully steerable parabolic radio telescopes of 45 metre diameter, observing at metre wavelengths. It is the largest and most sensitive radio telescope array in the world at low frequencies. It played a vital role in this discovery because it has a unique low radio frequency range and a flexibility that allows it to observe many pulsars simultaneously. The GMRT was upgraded in 2019 to enhance its capabilities.
The Indian Pulsar Timing Array (InPTA) is a collaboration of researchers from various institutes across India and Japan who use the GMRT to study pulsars and gravitational waves. The InPTA is part of a larger global network of pulsar timing arrays that aims to detect and study gravitational waves in the nano-hertz frequency range. The results of this network were published on June 30, 2023, in a paper titled "First results from the EPTA+InPTA pulsar timing array: limits on low-frequency gravitational wave sources" in the journal Monthly Notices of the Royal Astronomical Society.
The paper reports that the team has achieved a sensitivity level that is close to the expected strength of the gravitational wave background, which is a stochastic signal produced by a large number of supermassive black hole binaries in distant galaxies. These binaries are pairs of black holes that orbit each other and emit gravitational waves as they lose energy and spiral closer together. The team expects to make a definitive detection of this background in the near future, which will open a new window into the gravitational wave spectrum and reveal new insights into the formation and evolution of galaxies and black holes.
The discovery of ultra-low frequency gravitational waves will complement the previous detections of high-frequency gravitational waves by ground-based interferometers such as LIGO and VIRGO, and medium-frequency gravitational waves by space-based missions such as LISA. Together, these observations will cover a wide range of frequencies and sources of gravitational waves, allowing us to probe the mysteries of gravity and the universe.
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FAQ's
Which is the largest radio telescope in India?
The Giant Metrewave Radio Telescope
The Giant Metrewave Radio Telescope (GMRT), located near Narayangaon, Pune in India, is an array of thirty fully steerable parabolic radio telescopes of 45 metre diameter, observing at metre wavelengths. It is the largest and most sensitive radio telescope array in the world at low frequencies.
Which is the largest telescope radio interferometry?
Five-hundred-metre Aperture Spherical Telescope
The largest single radio telescope in the world is the Five-hundred-metre Aperture Spherical Telescope (FAST), located in a natural depression in Guizhou province in China. It was completed in 2016.
Where is the largest radio telescope in the world called?
The Five-hundred-meter Aperture Spherical radio Telescope (FAST; Chinese: 五百米口径球面射电望远镜), nicknamed Tianyan (天眼, lit. "Sky's/Heaven's Eye"), is a radio telescope located in the Dawodang depression (大窝凼洼地), a natural basin in Pingtang County, Guizhou, southwest China.
Where is one of the largest radio telescopes located?
The largest single dish radio telescope in the world is the Arecibo Radio Observatory in Puerto Rico. It was built into a large limestone sinkhole and is about 1,000 feet (305 meters) across, 167 feet deep, and covers an area of about twenty acres.
