Canada's CHIME telescope detects the universe's hydrogen glow on its own, opening a new way to study dark energy

Astronomers using the Canadian Hydrogen Intensity Mapping Experiment (CHIME) have detected the faint radio glow of hydrogen gas from when the universe was about five billion years old — using only CHIME’s own data, without help from other telescopes.

The achievement, detailed in two papers published in The Astrophysical Journal on 28 September 2026 (Detection of the Cosmological 21 cm Signal in Autocorrelation at z ~ 1, DOI: 10.3847/1538-4357/ae9835; Interpretation of 21 cm Autopower Spectrum Measurement at z ~ 1, DOI: 10.3847/1538-4357/ae9747), marks the first “standalone” or autocorrelation detection of the cosmological 21 cm signal by CHIME, according to the University of British Columbia.

CHIME, a radio telescope near Penticton, British Columbia, was built to map hydrogen gas in the early universe to study dark energy, the mysterious force driving the universe’s accelerating expansion. Until now, it had to cross-correlate its observations with galaxy survey data from other telescopes — surveys that cost millions of dollars more and only probe regions dense enough to form stars.

The new result is based on 94 nights of observations collected in 2019. More than a year of testing convinced the team the faint signal was real. “We worked very hard to convince ourselves that this wasn’t a false alarm,” said co-author Dr Arnab Chakraborty, a postdoctoral fellow at the University of Toronto who first proposed the finding. The companion paper reports that roughly two per cent of the universe’s hydrogen was in neutral atomic form at that time, broadly consistent with other measurements.

“This is a completely new technique for probing the cosmos,” said CHIME principal investigator Dr Mark Halpern of UBC. “It’s a bold new step in the global cosmology program and a Canadian success story.”

The researchers have nearly seven years of observations banked and are now extending the analysis to periods when the universe was only three billion years old.

Sources

• UBC News, “Canadian telescope directly maps earliest glow of hydrogen, opening a new window on the universe”, 2026-09-26 — https://news.ubc.ca/2026/09/canadian-telescope-maps-earliest-glow-of-hydrogen/
• phys.org, “Hydrogen’s distant glow opens new way to investigate dark energy”, 2026-09-28 — https://phys.org/news/2026-09-hydrogen-distant-dark-energy.html
• ThePrint, “Indian scientists spot hydrogen from 8 billion years ago. It could help decode dark energy”, 2026-09-28 — https://theprint.in/science/indian-scientists-hydrogen-detection-8-billion-years-dark-energy-chime/3056092/