Canadian Telescope Maps Ancient Hydrogen Without Help From Other Telescopes

Scientists have developed a new way to map the complex expansion of the universe using data from a single Canadian radio telescope.

The Canadian Hydrogen Intensity Mapping Experiment, or CHIME, has shown for the first time that it can chart the distribution of hydrogen gas across the ancient universe using only its own observations. The result took seven years to verify, but it could give researchers a faster and more cost-effective way to study the cosmos.

CHIME detects hydrogen from 3 billion years ago

According to the authors of a new study published Monday, September 28, in The Astrophysical Journal, CHIME could provide scientists with an independent method for investigating dark energy—the poorly understood force thought to be causing the universe to expand at an accelerating rate.

“Hydrogen is the most common element in the universe and the raw material from which stars are formed,” study co-author Arnab Chakraborty, a postdoctoral fellow at the University of Toronto, said in a statement. “Their weak radio emissions act like cosmic trackers, revealing how matter is distributed in space.”

CHIME is a series of radio telescopes located primarily near Penticton, British Columbia. The array maps the entire northern sky every day. Before this study, CHIME’s observations had to be confirmed with data from other telescopes—a process that can be expensive and time-consuming.

A seven-year effort to confirm the signal

The research team wanted CHIME to detect ancient hydrogen using its own data and serve as an independent measurement of the gas. The new paper, nearly a decade in the making, is based on 94 nights of observations collected in 2019 and repeatedly checked before publication.

CHIME can detect radio signals from as far back as 3 billion years ago, when the universe was only a fraction of its current age following the Big Bang.

“We tried hard to convince ourselves that this was not a false alarm,” Chakraborty said. “After all the tests, the signal remained. This gave us confidence that we were seeing real hydrogen from distant space.”

What neutral hydrogen can reveal about the universe

A related paper in The Astrophysical Journal provides more information about where hydrogen is found throughout the universe. The study suggests that about 2% of hydrogen exists as neutral atoms—atoms containing one proton and one electron and therefore carrying no overall electric charge.

That result is “almost consistent” with measurements from other telescopes, according to co-author Shabbir Shaikh.

Mapping the distribution of hydrogen could help scientists investigate how the universe expanded at different points in its history. It may also provide new insights into dark energy and the large-scale structure of the cosmos.

CHIME’s next observations

The research team plans to analyze the remaining seven years of CHIME observations to gather more information about hydrogen gas in the distant universe.

Reference: Amiri, M., Bandura, K., Chakraborty, A., Kliche, J., Dobbs, M., Foreman, S., Gray, L., Halpern, M., Hill, A. S., Hinshaw, G., Hofer, C., Joseph, A., Krueger, N., Landecker, T. L., van Lieshout, R., McEachern, J., Masui, K. W., Mena-Parra, J., Miller, K., and Wolf, D. (2026). “Detection of a cosmological 21 cm signal in autocorrelation at z ~ 1 from the Canadian Hydrogen Intensity Mapping Experiment.” The Astrophysical Journal, 1009(2), 159.