For the first time ever, scientists have tracked a mysterious type of space explosion to its original source 3.6 billion light-years away.
Fast radio bursts, or FRBs, are ultraluminous and energetic pulses of light in the night sky that can barf out as much energy in a few milliseconds as the Sun does in 80 years. Nobody knows what powers these intense cosmic flare-ups, but scientists have speculated that they may be generated by neutron stars and black holes—or maybe even an advanced alien intelligence.
FRBs come in two varieties: repeaters, which flash multiple times at the same spot, and non-repeaters, which are one-off bursts. Scientists first traced a repeating FRB back to its host galaxy in 2017, after observing a sequence of bright pulses, which confirmed that these events are extragalactic in origin. The one-off pulses remained mysterious, however.
Now, researchers led by Keith Bannister, an engineer at Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO), have become the first to pinpoint the host galaxy of a non-repeating FRB using extremely sensitive equipment.
"If we were to stand on the Moon and look down at the Earth with this precision, we would be able to tell not only which city the burst came from, but which postcode, and even which city block," Bannister said.
The one-off burst, which has been named FRB 180924, was detected on September 24, 2018, by the Australian Square Kilometre Array Pathfinder (ASKAP).
The ASKAP facility consists of 36 large radio antennas across an area of four square kilometers. The array is extremely sensitive to the tiny time gaps, shorter than a billionth of a second, between each antenna’s reception of light from an astronomical event. These time lags correlate to small differences in the distance that light from the same event traveled to each antenna, and that can help lead scientists back to the source.
Up until this point, one-off FRBs have sparkled and faded before scientists can localize their origins—like a suspect hanging up the phone before the cops can trace the call in a movie—but ASKAP captured enough of immediate data to zoom in on FRB 180924’s whereabouts.
The team identified the source within the outskirts of a distant galaxy that is similar in size to the Milky Way, but that it is not forming as many new stars. Follow-up observations by the Gemini South Telescope and the Very Large Telescope, both located in Chile, as well as the Keck Observatory in Hawaii, suggest that one-off and repeating FRBs may be generated by different mechanisms.
While scientists still don’t know what causes FRBs, the new discovery provides a roadmap for detecting more of them, which will help to further resolve the origins of these astronomical enigmas.