Most astronomy can’t be done in a lab — not even a lab big enough to span countries. But we observational folks still find ways to probe the universe, and in a new paper in Nature Astronomy led by Liam Connor, researchers discuss how they are now using fast radio bursts (FRBs) to search for material in the outskirts of galaxies.

Their study reviews 474 of these brief, powerful bursts that were detected by the CHIME radio array in Canada. In this data set, they found that 24 FRBs shined light through the outskirts of galaxies. This was revealed in interactions between the radio pulses and the gas in the galaxy’s halo. As the radio light hits the gas, interactions can disperse the light, changing its frequency and delaying its arrival at our detectors. How much the gas affects the fast radio burst reflects the density and volume of the gas – essentially allowing us to measure physical properties far off in the universe.

According to Connor: Our study shows that FRBs can act as skewers of all the matter between our radio telescopes and the source of the radio waves … We have used fast radio bursts to shine a light through the halos of galaxies near the Milky Way and measure their hidden material.

These 24 FRBs are a fairly small sample, but it is one we expect to see exploding in size. FRBs were only discovered in 2007, and numerous surveys and new instrumentation are planned to help make their discovery more efficient. Once enough systems have been probed that we can start to draw conclusions about the halos of galaxies, we’ll let you know.

More Information

Caltech press release

“The observed impact of galaxy halo gas on fast radio bursts,” Liam Connor & Vikram Ravi, 2022 July 4, Nature Astronomy