Flash of radio waves detected by astronomers traced back to its galactic origins

Two independent groups have localized flashes of these millisecond-long bursts from Milky Way-esque galaxies.


Just days apart, two research groups have found flashes of "fast radio bursts" that appeared to last just a fraction of a second. Fast radio bursts, or FRBs, are one of astronomy's hottest topics — and biggest mysteries. They are intense emissions of radio waves that usually last milliseconds long and are made up of a characteristic, sweeping pattern of radio pulsars. While being one of the hottest topics in astronomy, the source of these FRBs is still a mystery.

Recently, astronomers managed an incredible feat, not once, but twice in the span of a week. They identified the host galaxy from which a flash of radio waves lasting a fraction of a second — was picked up by detectors on Earth. The results have taken humanity a step closer to understanding where in the universe such mysterious fast radio bursts come from.

The first of these recent announcements came in the last week of June, when an international team claimed to have traced the FRB 180924, generated from a Milky Way-like galaxy to its source, 3.6 billion light-years away. More recently, Vikram Ravi and colleagues from Caltech reported their findings in a Nature paper, pinpointing the source of 'fast radio burst 190523' with a technique known as radio interferometry. The burst seemed to originate from a huge galaxy much like the Milky Way.

Flash of radio waves detected by astronomers traced back to its galactic origins

This artist’s impression of the cosmic web, the filamentary structure that fills the entire Universe, being illuminated by the Fast Radio bursts. Image credit: M Weiss/CfA

"It’s exciting that they have localized a burst from such a distant galaxy," Keith Bannister, who led the team that found the host galaxy of the FRB 180924. There are distinct signatures in fast radio burst (FRB) signals from space. For instance, these millisecond-long flashes of radio waves sweep downward in frequency — suggesting they've traveled billions of light-years from their source to reach Earth. But so far, astronomers are clueless as to what celestial event/body actually produces FRBs.

Ravi's team used an array of 10 radio dishes at the Owens Valley Radio Observatory to quickly zero in on the most recently studied burst, FRB 190523. They traced the signal back to an area 1,000 times tighter than the previous FRB detected. But the newer burst also came from a distance much farther away.

Signals from distant sources are might useful to researchers. In addition to simply understanding what produces them, these radio waves pulses or flashes can also hold information on the hot, sparse gas between galaxies that it travels through. This gas, invisible on telescopes, holds the bulks of normal (non-dark) matter in the universe and helps form the large-scale "web" shaping the larger cosmos. Studying this matter is crucial to our current understanding of how the galaxies grow and the universe expands.

With new radio telescopes on the horizon, the hunt for fast radio bursts is starting to provide some answers — alongside plenty more questions.

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