SARAS Radio Telescope

Syllabus: General Studies Paper 3

India’s SARAS radio telescope provides astronomers clues to the nature of Universe’s first stars and galaxies.

• In a first-of-its-kind work, using data from SARAS 3, researchers from the Raman Research Institute (RRI), Bengaluru, the Commonwealth Scientific and Industrial Research Organisation (CSIRO) in Australia, along with collaborators at the University of Cambridge and the University of Tel-Aviv, estimated the energy output, luminosity, and masses of the first generation of galaxies that are bright in radio wavelengths.
• Scientists have determined properties of radio luminous galaxies formed just 200 million years post the Big Bang, a period known as the Cosmic Dawn thus providing an insight to the properties of the earliest radio loud galaxies that are usually powered by supermassive black holes.

About SARAS

• Shaped Antenna measurement of the background Radio Spectrum 3 (SARAS) telescope.
• It is indigenously designed and built at Raman Research Institute — was deployed over Dandiganahalli Lake and Sharavati backwaters, located in Northern Karnataka, in early 2020.
• The results from the SARAS 3 telescope are the first time that radio observations of the averaged 21-centimeter line have been able to provide an insight to the properties of the earliest radio loud galaxies that are usually powered by supermassive black holes.
• SARAS 3 has improved our understanding of astrophysics of Cosmic Dawn, telling us that less than 3 percent of the gaseous matter within early galaxies was converted into stars, and that the earliest galaxies that were bright in radio emission were also strong in X-rays, which heated the cosmic gas in and around the early galaxies.
• It is used to reject claims of the detection of an anomalous 21-cm signal from Cosmic Dawn made by the EDGES radio telescope developed by researchers from Arizona State University (ASU) and MIT, USA.
• This refusal helped restore confidence in the concordant model of cosmology that was brought into question by the claimed detection.
• The analysis has shown that the 21-cm hydrogen signal can inform about the population of first stars and galaxies.

About the study

• Scientists study the properties of very early galaxies by observing radiation from hydrogen atoms in and around the galaxies, emitted at a frequency of approximately 1420 MHz.
• The radiation is stretched by the expansion of the universe, as it travels to us across space and time, and arrives at Earth in lower frequency radio bands 50-200 MHz, also used by FM and TV transmissions.
• The cosmic signal is extremely faint, buried in orders of magnitude brighter radiation from our own Galaxy and man-made terrestrial interference.
• Therefore, detecting the signal, even using the most powerful existing radio telescopes, has remained a challenge for astronomers.
• Usage: Even non-detection of this line from the early Universe can allow astronomers to study the properties of the very first galaxies by reaching exceptional sensitivity.

Question: What are the key characteristics of India’s SARAS radio telescope?