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4w ago

CHIME Detects Faint 21-cm Hydrogen From About 8 Billion Light-Years

Proving CHIME can map large-scale matter using only its own data, the detection could enable independent dark-energy measurements if removed cosmological modes are restored.

Astronomers working with a unique radio telescope in British Columbia have achieved the most distant measurement to date that shows how hydrogen atoms are distributed in the deep universe.
The CHIME telescope, housed in British Columbia, Canada, was built in 2017 specifically to study how hydrogen, the most abundant substance in the universe, was distributed in the early universe | Wikimedia Commons
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Overview

  • The CHIME collaboration published its result in The Astrophysical Journal on Monday, Sept. 28, 2026, reporting the first standalone autocorrelation detection of redshifted 21-cm hydrogen from roughly 8 billion light-years away.
  • The finding rests on 94 interference-free nights selected from roughly 2,000 days of observations and on more than two years of analysis and checks to separate the very faint hydrogen glow from noise.
  • Galactic synchrotron emission and human-made radio interference are up to about 10,000 times stronger than the hydrogen signal, forcing the team to remove contaminated frequency modes to reach a robust detection.
  • Those removed modes currently prevent a direct measurement of the universe’s expansion rate, and the collaboration is now pursuing techniques to recover those cosmological modes so the data can constrain dark energy.
  • CHIME’s fixed, wide-field design has amassed nearly seven years of data, which the team plans to mine to probe earlier cosmic epochs and to test whether radio intensity mapping can offer a faster, lower-cost alternative to galaxy surveys.