Intense, brief flashes of radio light called fast radio bursts (FRBs) travel across billions of light-years to reach Earth, passing through a fog of matter along the way. The bursts’ origins are unclear but may originate from highly magnetized dead stars called magnetars. The denser the fog through which FRBs travel, the more dispersed their signals become—similar to the way a prism splits white light into a rainbow of colors.
Thanks to this dispersive property, FRBs make excellent tracers of how ordinary matter is distributed in the universe; ordinary matter is the same stuff that makes up people, planets, stars and anything made of subatomic particles called baryons. As the FRB radio beams pass through this matter in our universe, they can essentially map out how much is present and how clumpy it is.
In a new Nature Astronomy study, researchers show how these FRB measurements can help solve some of the biggest questions in cosmology.
“We’ve established that FRBs are a leading probe of the distribution of matter in the universe,” says Kritti Sharma (MS ’24), lead author of the new study and a graduate student working with Vikram Ravi, a professor of astronomy at Caltech and a co-author of the paper.
“These FRB data can be used to enhance cosmology experiments that are trying to answer questions about dark matter, dark energy and the mass of neutrinos.”
Where clumping gets complicated
Many questions persist about the nature of dark energy, a repulsive force or substance that is causing our universe to fly apart at increasing speeds, and about dark matter, a substance that far outweighs matter in our universe but cannot be seen. Mysteries about neutrinos, ghostly particles that pass freely through ordinary matter, also endure—including the particles’ mass, a measurement that could help reveal how large-scale galactic structures in the universe formed.
Dark energy, dark matter and neutrinos are all predicted to influence how matter clumps together, so scientists use sky surveys to map this clumping and gain clues to the nature of these cosmological phenomena. The problem is that feedback processes inside galaxies can also affect how smooth or clumpy matter is, muddying researchers’ ability to precisely measure the cosmological effects.
All galaxies harbor supermassive black holes at their centers, which voraciously feed on nearby matter while also ejecting winds of hot, ionized—or charged—gas into their surroundings. Exploding stars can also expel energy into galactic neighborhoods. This feedback plays a role in smoothing out the material outside galaxies, making it less clumpy.
“The feedback process thins the gas around the galaxies, redistributing matter across vast distances. It smooths out clumps of matter in a way that looks astonishingly similar to what massive neutrinos do, or what dark energy or dark matter theories predict,” Ravi says. “Unless scientists can independently measure this contribution from feedback, they can’t tell these effects apart.”
FRBs offer a cleaner measure
The new study, which analyzed a sample of about 100 FRBs, is the first to directly measure the impact of feedback on clumpy matter in the large-scale regions around and between galaxies. The results show that galactic feedback does indeed smooth surrounding material, making it less clumpy. However, it does so to a lesser extent than has been measured previously by state-of-the-art surveys, including the eROSITA X-ray telescope and the former microwave-based Atacama Cosmology Telescope in Chile, which ended in 2022.
“Our analysis of FRBs reveals how gas ejected by astrophysical feedback suppresses cosmic structure, delivering constraints competitive with X-ray and microwave surveys,” says co-author Elisabeth Krause (Ph.D. ’12), a professor of astronomy and physics at the University of Arizona. “This is amazing considering we only had about 100 FRBs in our sample. It’s only the beginning.”
Publication details
Kritti Sharma et al, Signatures of suppressed matter clustering revealed by fast radio bursts, Nature Astronomy (2026). DOI: 10.1038/s41550-026-02957-9
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California Institute of Technology
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Fast radio bursts could help disentangle galactic feedback from dark matter effects (2026, September 8)
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