India's SARAS Telescope Provides Information About The Universe's First Stars And Galaxies

The SARAS radio telescope in India has assisted scientists in determining the features of the first bright radio galaxies generated 200 million years after the Big Bang, a period known as the Cosmic Dawn. A multinational group of scientists published their findings in Nature Astronomy, providing insight into the features of the oldest radio-loud galaxies, often fueled by supermassive black holes. A group of scientists led by Saurabh Singh of the Bengaluru-based Raman Research Institute (RRI) calculated the energy production, luminosity, and masses of the first generation of radio-bright galaxies.

In early 2020, the Shaped Antenna measurement of the backdrop Radio Spectrum 3 (SARAS) telescope was placed above Dandiganahalli Lake and Sharavati backwaters in northern Karnataka. Only 200 million years after the Big Bang, scientists could gaze back in time and provide new insight into galaxies' features. In addition to RRI, researchers from the (CSIRO) Commonwealth Scientific and Industrial Research Organisation in Australia, as well as collaborators from the Universities of Cambridge and Tel Aviv, took part in the study to estimate the energy output, luminosity, and masses of the first generation of radio-bright galaxies.

Scientists found radiation released by hydrogen atoms in and around galaxies at a frequency of about 1420 MHz. As it travels across space and time to us, the radiation is stretched by the universe's expansion and reaches Earth in lower frequency radio bands, 50-200 MHz, which are also used by FM and TV transmissions. The cosmic signal is exceedingly faint, buried beneath orders of magnitude stronger radiation from our Galaxy and man-made terrestrial interference, making identification difficult. The researchers highlighted how even the absence of this line from the early cosmos allows astronomers to investigate the features of the very first galaxies with amazing sensitivity.

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