For the first time, the Canadian Hydrogen Intensity Mapping Experiment (CHIME) has demonstrated that it can detect the extremely faint radio glow of hydrogen gas from the distant universe using only its own observations. 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. Understanding dark energy remains one of the biggest unresolved problems in modern physics.
The achievement is also an important milestone for CHIME, which was originally designed with this type of measurement in mind. The findings were published in The Astrophysical Journal. "Hydrogen is the most common element in the universe and the raw material from which stars form," said co-author Dr.
Arnab Chakraborty, postdoctoral fellow at the University of Toronto who first proposed the finding. "Its faint radio emission acts like a cosmic tracer, revealing how matter is distributed across space." Scientists have proposed competing explanations for the nature of dark energy. Because CHIME can now make these measurements using its own data, researchers can test those ideas independently and gather evidence that could support or challenge existing theories.
"This is a completely new technique for probing the cosmos, delivered by an instrument that was conceived, built and funded by Canadians," said co-author Dr. Mark Halpern, professor in the UBC department of physics and astronomy and CHIME principal investigator. "It's a bold new step in the global cosmology program and a Canadian success story." CHIME is a radio telescope located near Penticton, British Columbia, and hosted by the National Research Council of Canada (NRC).
The instrument surveys the entire northern sky every day. The project brings together researchers from across Canada, including scientists at the University of British Columbia, McGill University, the University of Toronto, and the Dominion Radio Astrophysical Observatory (NRC). Other North American collaborators, including Arizona State University, also participate in the effort.
One of CHIME's main goals is to chart how hydrogen gas was distributed in the earlier universe. By measuring that large-scale structure, astronomers can reconstruct how the universe expanded over time and use those measurements to investigate dark energy. Until now, CHIME researchers needed to compare their radio observations with galaxy survey data collected by other telescopes.
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