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

Source: The post is based on the article “India’s SARAS radio telescope provides astronomers clues to the nature of Universe’s first stars and galaxies” published in PIB on 28th November 2022.

What is the News?

Raman Research Institute RRI) in Bengaluru have determined properties of radio luminous galaxies formed just 200 million years after the Big Bang, a period known as the Cosmic Dawn. This was done using SARAS Telescope.

What is the SARAS Telescope?

Shaped Antenna measurement of the background Radio Spectrum 3 (SARAS) Telescope is indigenously designed and built at Raman Research Institute(RRI).

Aim: To detect extremely faint radio wave signals from the depths of time, from our “Cosmic Dawn” when the first stars and galaxies formed in the early Universe.

What is Cosmic Dawn?

For a period of roughly 100 million years in the early universe, starting about 380,000 years after the big bang, the cosmos was completely dark. 

Then, stars and galaxies began to form, emitting light and ionizing the intergalactic hydrogen gas in a process called cosmic dawn.

Detecting a faint signal from cosmic dawn is extremely difficult. The celestial signal is exceptionally faint – buried in sky radio waves that come to us from the gas in our own Galaxy, the Milky Way, which are a million times brighter. 

Besides, this cosmic signal is in a radio wavelength band used by numerous terrestrial communications equipment and TV and FM radio stations, which makes detecting the extra-terrestrial signal extremely difficult.

However, RRI scientists and engineers have designed the SARAS radio telescope to discern signals from Cosmic Dawn.

What has the SARAS 3 Telescope found about Cosmic Dawn?

In 2020, the SARAS telescope was deployed in lakes in Northern Karnataka, on Dandiganahalli Lake and Sharavati backwaters by the RRI.

The telescope has improved the understanding of the astrophysics of Cosmic Dawn. It has shown 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.