Pinpointing the extragalactic origin of a single fast radio burst

The origin of a single, transient radio pulse has been pinpointed to a distant galaxy several billion light years away, representing the first localization of a non-repeating fast radio burst (FRB). The FRB’s burst source and host galaxy are distinct from those of the only other localized FRB, a repeating fast radio burst pegged to its galaxy in 2017. Short blasts of radio energy from powerful, yet currently unknown, astrophysical processes travel far and wide across vast intergalactic expanses. Upon reaching Earth, these pulses – which often last no longer than a few milliseconds – are mere electromagnetic whispers that require sensitive radio telescopes to detect. Although FRBs are known to have extragalactic origins, the host galaxies from which they were emitted remain mysterious, largely due to difficulties in precisely locating the radio emission. Understanding where these FRBs are coming from, and how far the signals had to travel to reach Earth, could help determine what produces them and allow FRBs to be used to measure and map the vast corridors of intergalactic medium that bridge the space between galaxies. Most identified FRBs are known to be non-repeating, occurring only as a single flash of detectable energy. Two have been shown to repeat; one of these, FRB 121102, is the only FRB to date that has been localized with enough accuracy to determine its host galaxy. Here, Keith Bannister and colleagues report on the detection and localization of a new, non-repeating FRB. Using a 36-antenna radio interferometer telescope with a specialized mode designed to locate FRBs, Bannister et al. discovered the non-repeating FRB 180924, named after the date it occurred. They find it came from a medium-sized galaxy over 4 billion light years from Earth. What’s more, the results show that the properties of the burst source and its host galaxy are markedly different than those of the only other localized FRB. “…if the hosts of other bursts are similarly luminous as the host of FRB 180924,” say the authors, “identifying hosts at high redshift will be easier than if bursts are exclusively hosted in dwarf galaxies, like the host galaxy of FRB 121102.”

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