Scientists mystified after capturing 9 billion-year-old radio signal from far-away galaxy
From space exploration to movies and pop culture, mankind has been fascinated with the idea of getting in touch with life on other planets, to know if we are alone in the universe. While UFO sightings have been reported for decades, radio signals from an ancient galaxy detected in 2023 might shed light on more insights into the universe, that were previously unknown to humans. According to VICE, scientists have discovered a radio signal known as the 21-centimeter line which can prove to be the key to knowing more about distant galaxies.
This is not the first time experts have stumbled upon radio signals in space, but this new signal that they have detected, originated in a galaxy that existed almost 9 billion years ago. Scientists were able to spot the signal with the help of a natural telescope created by another celestial body known as a gravitational lens. Then they magnified the signals 30 times over and generated insights about the universe in its early days of existence. The 21-centimeter line was named after the 21-centimeter wavelength that neutral hydrogen atoms emit in deep space.
These hydrogen atoms are the key to the formation of stars in the galaxies, but neutral hydrogen emits faint radio signals that can only be seen at low “redshifts." It's a term used for the measurement that constrains the age and distance of celestial bodies and objects. A scientist duo led by Arnab Chakraborty who is a post-doctoral research fellow at McGill University, used the Giant Metrewave Radio Telescope in India to spot “the highest redshift detection in emission from an individual galaxy to date." The galaxy detected by the duo through the radio waves has been named SDSSJ0826+5630.
“The strong gravitational lens, nature’s gift, magnifies the weak emission signal coming from distant objects, enabling us to peer through the high-redshift universe,” Chakraborty and his co-author, Nirupam Roy of the Indian Institute of Science, mentioned in their study. “Strong gravitational lensing phenomenon can significantly amplify the faint signal, enabling us to detect the [hydrogen] signal from galaxies at higher redshifts in a reasonable observation time,” the team added. These gravitational lenses form naturally when massive objects like a galaxy cluster find their position in front of distant background objects that don't fall in the line of sight from Earth.
These foreground objects in space are large enough to warp the spacetime around them and create a "cosmic funhouse mirror" that can magnify the objects in the distant background. The gravitational lens in front of SDSSJ0826+5630 helped Chakraborty and Roy pick out the 21-centimeter signal at this record-breaking distance, making them the first duo to trace this signal so far to an individual galaxy.
“These results, for the first time, demonstrate the feasibility of observing high-redshift, the 21-centimeter emission, in a lensed system with a modest amount of telescope time and open up exciting new possibilities for probing the cosmic evolution of neutral gas with existing and upcoming low-frequency radio telescopes in future,” the team concluded in the study. Chakraborty and Roy's study has opened a door for other astronomers to explore the formation of galaxies and stars as well as the origin of the cosmos.