Radio signals from galaxy 9 billion light years away reveal secrets of the early universe

‘It’s the equivalent to a look-back in time of 8.8 billion years’

Astronomers have captured radio signals from a galaxy nine billion light years away, an advance that reveals more about how stars formed in the early universe.

The radio signals are from the most distant galaxy discovered so far, at a specific wavelength known as the 21cm line, according to a study published recently in the journal Monthly Notices of the Royal Astronomical Society.

“A galaxy emits different kinds of radio signals. Until now, it’s only been possible to capture this particular signal from a galaxy nearby, limiting our knowledge to those galaxies closer to Earth,” study co-author Arnab Chakraborty from McGill University said in a statement.

“But thanks to the help of a naturally occurring phenomenon called gravitational lensing, we can capture a faint signal from a record-breaking distance,” Dr Chakraborty said.

Gravitational lensing is a phenomenon that magnifies the signal coming from distant objects in the cosmos, something that can help astronomers peer into the early universe.

“In this specific case, the signal is bent by the presence of another massive body, another galaxy, between the target and the observer,” the McGill University cosmologist explained.

“This effectively results in the magnification of the signal by a factor of 30, allowing the telescope to pick it up,” he added.

The new findings will help unravel the composition of galaxies at much greater distances from Earth, scientists explained.

Analysing the new signals, they could study a distant star-forming galaxy known as SDSSJ0826+5630 and measure its gas composition for the first time.

They observed that the atomic mass of the gas content of the galaxy was strangely neatly twice the mass of the more easily visible stars.

Researchers said the signals were also from the galaxy when the universe was only about 4.9 billion years old, enabling them to get a glimpse into the secrets of the early universe.

“It’s the equivalent to a look-back in time of 8.8 billion years,” Dr Chakraborty said.

The results also demonstrate the potential of observing galaxies far away using gravitational lensing.

Researchers said the approach can open up new opportunities for investigating the evolution of stars and galaxies in the cosmos using existing low-frequency radio telescopes.