SARAS 3 telescope throws light on the nature of early stars and galaxies

Using its data, astronomers were able to determine properties of radio luminous galaxies formed just 200 million years post the Big Bang

Updated - November 29, 2022 06:18 pm IST

Published - November 28, 2022 09:45 pm IST - Bengaluru

SARAS 3 Radio telescope developed by Raman Research Institute deployed on water surfaces for the experiment. Photo: Handout

SARAS 3 Radio telescope developed by Raman Research Institute deployed on water surfaces for the experiment. Photo: Handout

SARAS 3, a radio telescope designed and built at the Raman Research Institute (RRI) here has provided clues to the nature of the Universe’s first stars and galaxies.

Using data from the telescope which has been deployed over the Dandiganahalli Lake and Sharavati backwaters since 2020, astronomers and researchers have been able to determine properties of radio luminous galaxies formed just 200 million years post the Big Bang, a period known as the Cosmic Dawn.

Researchers Saurabh Singh from the RRI and Ravi Subrahmanyan from the Commonwealth Scientific and Industrial Research Organisation (CSIRO) in Australia, along with collaborators at the University of Cambridge and University of Tel Aviv, have used data from SARAS 3 to throw light on the energy output, luminosity, and masses of the first generation of galaxies that are bright in radio wavelengths.

“The results from the SARAS 3 telescope are the first time that radio observations of the averaged 21-centimetre line have been able to provide an insight into the properties of the earliest radio loud galaxies that are usually powered by supermassive black holes,” said Subrahmanyan, former director of the RRI and currently with CSIRO.

Research findings

Explaining the research findings, Prof. Singh said SARAS 3 had improved the understanding of astrophysics of Cosmic Dawn by telling astronomers that less than 3% 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.

The results of the findings have been published in the journal Nature Astronomy.

In March, the SARAS 3 team used the same data 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.

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