Indian telescope SARAS finds clues to the first galaxies in the universe!  |

Indian telescope SARAS finds clues to the first galaxies in the universe! |

Located about 20,000 light-years away in the constellation Scorpius (the Scorpion), Terzan 1, pictured here, is one of about 150 globular clusters belonging to our galaxy, the Milky Way.  (NASA)

Representative picture


Humanity’s fascination with the secrets of the universe is endless, and rightly so! After all, who wouldn’t want to know how our existence came about? The world has been collectively striving to find the answers for ages. And now he has taken a step forward, with India making a significant contribution to this leap!

A group of researchers from around the world have discovered the properties of radioluminous galaxies that formed just 200 million years after the Big Bang – a period known as the Cosmic Dawn!

And this one-of-a-kind work was made possible by a locally designed and built SARAS 3 radio telescope, which was deployed at Lake Dandiganahalli and the Sharavati Backwaters in North Karnataka. SARAS is an acronym for Antenna Shape Measurement of Radio Background Spectrum.

The research team involved scientists from the Raman Research Institute (RRI) based in Bengaluru and the Commonwealth Scientific and Industrial Research Organization (CSIRO) in Australia, as well as collaborators from the University of Cambridge and Tel Aviv University.

The study results, detailed in the journal Nature Astronomy, provide insight into the energy output, luminosity and masses of the first generation of galaxies.

Tracing the beginnings with a new method

Scientists typically study the properties of very old galaxies through the 21-centimeter line – a radio signal produced by hydrogen atoms in the early universe. This signal is emitted in and around galaxies at a frequency of about 1420 MHz. However, the signs are extremely faint and their detection is difficult even for the most powerful radio telescopes.

But now the study team has shown for the first time that even missing the 21-centimeter line of the early universe can allow astronomers to study the properties of early galaxies!

“The results from the SARAS 3 telescope are the first time radio observations of the 21-centimeter mean line have been able to provide insight into the properties of early radio-strong galaxies that are typically powered by supermassive black holes,” Subrahmanyan said, former director of RRI and author of the article.

While SARAS 2 was the first to inform the properties of the first stars and galaxies, SARAS 3 has gone a step further by improving our understanding of the astrophysics of Cosmic Dawn.

“SARAS 3 tells us that less than 3% of gaseous matter in early galaxies was converted into stars, and that early galaxies that were bright in radio emission were also strong in X-rays, which heated cosmic gas in and around of the first galaxies,” added Singh, another author of the paper.

Thanks to these developments, scientists have now been able to place limits on the masses of early galaxies, as well as their energy outputs in radio, X-ray and ultraviolet wavelengths. Furthermore, using a phenomenological model, an upper bound was also placed on the excess radiation at radio wavelengths.

“This is a first step for us in what we hope will be a decade of discoveries about how the universe evolved from darkness and emptiness to the complex realm of stars, galaxies and other celestial objects that we can see from Earth today,” Dr Eloy said. by Lera Acedo of the Cavendish Laboratory in Cambridge, who co-led the research.

Meanwhile, SARAS 3 has undergone a series of upgrades since its last deployment in March 2020. These improvements are expected to give even higher sensitivity in detecting the 21cm signal.

This study was published in the journal natural astronomy and available here.


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