A 9-billion-year-old signal could help explain dark energy
A Canadian radio telescope has detected the faint glow of hydrogen from billions of years ago using only its own observations, proving a long-awaited way to map the distant universe can actually work. CHIME can use this hydrogen signal to trace how matter is spread across space and measure how the universe has expanded over time, offering a powerful new way to investigate dark energy.
Key points
- CHIME has detected the faint radio glow of hydrogen from the distant universe using only its own observations.
- The signal came from hydrogen when the universe was about five billion years old, based on 94 nights of observations in 2019.
- The technique could offer a faster and less costly way to investigate dark energy.
The Canadian Hydrogen Intensity Mapping Experiment (CHIME) has for the first time demonstrated that it can detect the extremely faint radio glow of hydrogen gas from the distant universe using only its own observations. The findings were published in The Astrophysical Journal.
The result could give scientists a faster and less costly way to investigate dark energy, the still mysterious phenomenon believed to be accelerating the expansion of the universe. CHIME is a radio telescope near Penticton, British Columbia, hosted by the National Research Council of Canada, and surveys the entire northern sky every day.
What researchers found
The team's analysis showed the signal came from hydrogen in the distant universe when the universe was about five billion years old. It was based on 94 nights of observations collected in 2019.
Researchers used new data processing and analysis methods to extract the weak hydrogen signal from stronger interference, including radio noise from the universe, human technology and the telescope itself. After identifying a possible signature, they spent more than a year testing it.
After all the tests, the signal remained. That gave us confidence we were seeing real hydrogen from the distant universe.
— Dr. Arnab Chakraborty
Why the technique matters
Until now, CHIME researchers needed to compare their radio observations with galaxy survey data from other telescopes, which can cost millions of dollars more and mainly probe hot, dense regions where stars form. CHIME instead measures the combined radio emission from hydrogen itself, allowing researchers to examine larger regions, reach farther back in time and pursue similar questions at a fraction of the cost.
The measurement can also help test models of galaxy formation. In an accompanying paper, researchers analyzed what the signal says about how hydrogen was distributed throughout the universe.
