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Astronomers detect light from Universe’s earliest stars

An artist’s rendering of how the first stars in the universe may have looked. Illustration: N.R. Fuller, National Science Foundation
The faint radio signals come from the moment when the earliest stars were formed some 13.6 billion years ago
by TR Pakistan

Scientists from the United States have discovered a signal from the first stars to have emerged in the early universe about 180-million years after the Big Bang. This discovery, published in the international journal Nature, was made using a small radio telescope at a Commonwealth Scientific and Industrial Research Organization (CSIRO) observatory in Western Australia.

“Finding this miniscule signal has opened a new window on the early universe,” lead author Dr Judd Bowman of Arizona State University’s Experiment to Detect the Global Epoch of Reionization Signature (EDGES) project said in a statement.

Physicists believe that after the Big Bang, an ionized plasma was produced which cooled as the universe expanded. In the darkness that ensued for 180-million years, the effect of gravity brought matter together until stars were formed and ignited, bringing forth what scientists call the ‘cosmic dawn’.

These faint radio signals discovered by astronomers come from that moment, which took place 13.6 billion years ago.

The EDGES ground-based radio spectrometer, at CSIRO’s Murchison Radio-astronomy Observatory in Western Australia. Credit: CSIRO Australia

The discovery of these signals from most Earth-based sites was impossible because the Milky Way Galaxy and human-generated FM radio generate waves in the same band as the signals observed by physicists.

Read more: Scientists predict mid-century grand solar minimum

CSIRO’s Murchison Radio-astronomy Observatory (MRO) had been deemed by Dr. Bowman as ‘the best place on the planet for this work’, considering its location that is protected by a legislated ‘radio quiet’ zone up to 260 kilometers. This helps in keeping human activities that produce interfering radio signals to an absolute minimum in the area.

“Finding this signal is an absolute triumph, a triumph made possible by the extreme attention to detail by Judd’s team, combined with the exceptional radio quietness of the CSIRO site,” said Antony Schinckel, CSIRO’s head of Square Kilometre Array (SKA) Construction and Planning, who managed the development of the MRO.

“We worked hard to select this site for the long-term future of radio astronomy after exhaustive investigations. We believe we have the gold standard in radio quietness, the best site in the world.

“This is one of the most technically challenging radio astronomy experiments ever attempted. The lead authors include two of the best radio astronomy experimentalists in the world and they have gone to great lengths to design and calibrate their equipment in order to have convincing evidence for a real signal,” Mr Schinckel said.

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