Scientists from the Raman Research Institute (RRI) in Bengaluru have detected the faint glow of hydrogen from roughly eight billion years ago, when the universe was about five billion years old. The research was carried out as part of a joint Canadian, American and Indian effort. The findings were published in The Astrophysical Journal on September 28.
Researchers used the Canadian Hydrogen Intensity Mapping Experiment (CHIME) radio telescope in British Columbia to make the first “standalone” detection of hydrogen’s glow from the early universe. The telescope, built in 2017, used a method known as autocorrelation for the detection.
Other telescopes, including South Africa’s MeerKAT and China’s FAST, typically detect ancient hydrogen by cross-correlating it with existing galaxy maps. In this case, researchers relied entirely on CHIME’s own radio data, gathered across 94 nights of observation.
Dr. Arnab Chakraborty, a postdoctoral fellow at the University of Toronto who first proposed the finding, said hydrogen’s faint radio emission acts as a cosmic tracer. It can reveal how matter is distributed across space.
Dr. Saurabh Singh, associate professor at RRI and a co-author of the study, said CHIME’s lack of moving parts and high-accuracy measurements allow it to provide a daily snapshot of the sky at radio wavelengths as it drifts overhead.
The breakthrough opens a new path to studying dark energy, which is thought to drive the universe’s accelerating expansion and make up roughly 70 per cent of the universe. Researchers now have nearly seven years of CHIME data available and are working to extend the analysis to when the universe was only about three billion years old.
