Researchers from Montreal and India detect radio signal from galaxy 8.8 billion light years away


One of the dishes of the Giant Metrewave Radio Telescope near Pune, Maharashtra, India. (National Centre for Radio Astrophysics)

Researchers from Montreal and India have detected a radio signal from a galaxy that's nearly nine billion light years away. 

According to their findings, the signal would have been emitted when the universe was just 4.9 billion years old – long before our own solar system was formed about 4.5 billion years ago.

"It’s the equivalent to a look-back in time of 8.8 billion years," Arnab Chakraborty, the study's co-author and a post-doctoral researcher at McGill University, said in a news release.

Published in the journal Monthly Notices of the Royal Astronomical Society, the study explains how researchers were able to capture the most distant signal ever in a specific radio wavelength known as the 21 centimetre line, which is created by hydrogen, providing them with a unique glimpse of the early universe.

"A galaxy emits different kinds of radio signals," said Chakraborty, who studies cosmology in McGill's physics department. "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."

The distant star-forming galaxy is known as SDSSJ0826+5630. The signal also enabled researchers to determine that the atomic mass of the galaxy's hydrogen gas content is nearly double the mass of the stars that are visible to us.  

Normally, signals like these from distant galaxies are too faint to detect with current radio telescopes, which often look like rows of large television satellite dishes.

"But thanks to the help of a naturally occurring phenomenon called gravitational lensing, we can capture a faint signal from a record-breaking distance," Chakraborty said. "This will help us understand the composition of galaxies at much greater distances from Earth."

Nirupam Roy is the study's co-author and an associate professor of physics at the Indian Institute of Science.

"Gravitational lensing magnifies the signal coming from a distant object to help us peer into the early universe," Roy explained. "In this specific case, the signal is bent by the presence of another massive body, another galaxy, between the target and the observer. This effectively results in the magnification of the signal by a factor of 30, allowing the telescope to pick it up."

With funding from McGill University and the Indian Institute of Science, the researchers utilized the Giant Metrewave Radio Telescope, which is an array of 30 maneuverable radio telescope dishes in western India's Maharashtra state. They say their findings demonstrate that it's possible to detect similar signals from faraway galaxies with the help of gravitational lensing, opening new opportunities to study the early universe with existing low-frequency radio telescopes.