A Spree of Signals From Across the Universe

Scientists still don’t understand “fast radio bursts,” but they’ve gotten a lot better at discovering them.

An artist’s impression of fast radio bursts
An artist’s impression of fast radio bursts (OzGrav / Swinburne University of Technology)

About a decade ago, astrophysicists discovered an overlooked signal in some old telescope data: a flash of cosmic energy lasting only a few milliseconds. The signal seemed to have experienced a long and bumpy ride to Earth. Its radio waves had become distorted and were spread across a range of frequencies. This suggested that the radiation had traveled for billions of years, slowing down here and there as it sped through lush galaxies and luminous clouds of gas and dust.

Once astrophysicists convinced themselves that the signal wasn’t a glitch or noise in the telescope, they dubbed it a fast radio burst, or FRB. Since the first pulse was encountered in 2007, only 34 others have been found.

But on Wednesday, scientists in Australia announced a remarkable increase in the pace of discovery: Over the past year, they found 20 more FRBs.

The new batch of pulses was detected by an array of radio telescopes at the Murchison Radio-Astronomy Observatory in western Australia, in a desert region designated as a “radio quiet zone” so equipment can pick up cosmic pings from deep space without interference from earthly sources. Thirty-six dishes are spread out across nearly four miles, working together as a net to catch the signals. The results were published Wednesday in Nature.

Despite getting better at finding FRBs, astrophysicists know little more about the phenomena today than they did 11 years ago. No one knows exactly where they come from, how they form, and why, though astrophysicists suspect they emerge from giant black holes or neutron stars, the products of dramatic stellar explosions called supernovas. They also reckon that there are many more out there; scientists estimate that about 10,000 FRBs hurtle toward Earth every day, pulsing briefly with the intensity of the sun before vanishing.

The new additions include the brightest FRBs found to date. To some scientists’ chagrin, they don’t include one of the most sought-after types of FRBs: the kind that appears more than once. Astrophysicists have detected only one repeating FRB, known by the catalog-number–like name 121102. When 121102 was first recorded in 2012, observers expected the flash to be like all the others—fleeting. They assumed that because FRBs are so energetic and powerful, they likely destroy their source, preventing another burst from emerging in the same environment.

But 121102 kept flaring up, and as of last month, more than 200 pulses have been recorded in the past six years. The surprising behavior of FRB 121102 prompted scientists to rethink their proposed origin stories for FRBs. It also sparked some chatter about whether FRBs were the beacons of an extraterrestrial civilization trying to alert the rest of the cosmos to its presence.

Scientists eventually traced the source of 121102 to a small galaxy about 2.5 billion light-years from Earth, but they’re no closer to figuring out why it repeats.

It’s possible that in another decade, astrophysicists will be no further along in their quest to understand FRBs. But perhaps there’s still some magic to be found in this search. The presence of FRBs is a reminder—either comforting or terrifying—that no planet or solar system or galaxy is an island. That nature is capable of sending intergalactic messages flying through the cosmos, and that some of its inhabitants have the means to detect them.