Fast radio burst tracked to its galaxy of origin

Detection offers clue to matter hiding in space between galaxies

telescopes

HUNTING FOR GALAXIES  Radio telescopes at the Australia Telescope Compact Array (pictured) helped pinpoint the latest fast radio burst to a galaxy about 6 billion light-years away.

Alex Cherney

For the first time, astronomers have tracked a blast of cosmic radio waves to its home galaxy.

This burst originated in a galaxy roughly 6 billion light-years away in the constellation Canis Major, researchers report online February 24 in Nature. Identification of a host galaxy has eluded astronomers since the first report of a fast radio burst in 2007. All the bursts typically last for just a few milliseconds and never repeat (SN: 8/9/14, p. 22).

In April 2015, the Parkes radio telescope in Australia recorded a burst and alerted other observatories, Evan Keane, an astronomer with the Square Kilometer Array Organization in Macclesfield, England, and colleagues report. About two hours later, the Australia Telescope Compact Array picked up a faint radio glow that faded over the following six days. The position provided by ATCA led researchers to an elliptical galaxy, found with the Subaru telescope in Hawaii.

FOLLOWING THE TRAIL The radio burst (red line) originated in an elliptical galaxy (inset image) uncovered with the Subaru Telescope in Hawaii. David Kaplan and Dawn Erb

The eruption might have come from a smashup between white dwarfs or neutron stars, which are likely to be found among the host galaxy’s aging stellar population. Another burst reported last year, however, seemed to originate in a pocket of young stars (SN Online: 12/2/15). Fast radio bursts might come in two varieties, the researchers suggest, or perhaps the new detection came from an isolated cache of stellar infants or in a satellite of the elliptical galaxy.

By tallying the charged particles that the signal encountered, Keane and colleagues find that the density of plasma between galaxies is roughly the same as the density of protons, neutrons and electrons found in the early universe. Astronomers have had trouble finding where half of that matter went over the last 13.8 billion years. The radio burst bolsters a long-held suspicion that the missing matter has been hiding as ions in intergalactic space. 

Christopher Crockett is a freelance science writer and editor based in Arlington, Va. He has a Ph.D. in astronomy from the University of California, Los Angeles.

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