Dutch radio telescopes see a mysterious radio flash

Two of the world’s largest radio telescopes have picked up special radio flashes from the universe. It is related to the Westerbork Synthesis Radio Telescope (WSRT) in Drenthe and Lofar, a group of telescopes scattered across Europe whose core is also located in Drenthe. The newly refurbished Westerbork Telescope picked up 21 centimeters of short radio waves. Lovar saw longer waves, three meters. Never before has a radio flashed with waves longer than one meter. This is the first time that Lovar has ever seen a wireless flash. Dutch astronomers published This week about radio flashes in the magazine temper nature.

Radio bursts are one of the most mysterious and most dramatic manifestations in the universe. Flashes of light last for milliseconds, but sometimes generate the same amount of energy as the sun in a year. They cannot be seen with the naked eye. Astronomers watch it with radio telescopes. This was possible for the first time fourteen years ago and over a hundred have already been observed; from different star systems. The question is how the flashes are produced.

Five hundred light years away

To answer this question, Dutch astronomers studied the radio flash “20180916B”. It was first discovered in 2018 and repeats every 16 days. The source is located in a galaxy 500 light-years away, which is very close to the radio burst. The short distance and relatively regularity make these radio bursts a suitable target for astronomers.

One idea is that strong stellar winds are the source of 20180916B. The charged particles in the star’s outer layers become too hot to hold the star’s gravity, and then quickly blast off into space. Just like the solar wind. When stars orbit each other and one of these stars emits radio flashes, winds from the other star will block the flashes. Except when the twinkling star is on the side of the Earth. For example, a dual system may cause regular radio bursts. That was at least in theory.

But this theory is incorrect, according to Dutch researchers. Radio flashes consist of long wavelengths, but there is a difference in that: some radio waves are longer than others. When stellar winds cause the flashes, astronomers expect the short waves to reach telescopes on Earth more often than the long ones. Electron fog surrounding the stellar wind absorbs long waves. But astronomers saw two days of flashes with shorter waves, followed by three days with longer waves.

Very strong magnetic field

Read more about Lofar in Drenthe.

If the wind is not stellar, what causes the 20180916B radio to flash? “It’s probably a lone, slowly rotating neutron star with a strong magnetic field,” says Ines Pasteur Marazuela. She is the lead author of the study and a PhD student at the University of Amsterdam. A neutron star is the remnant, a highly compressed ball, of a massive deceased star.

Astronomers are thrilled that a long-wave radio flash can reach Earth. “As if you expect to have to hunt for treasure in a turbulent and turbid ocean, but suddenly you can see all the way to the bottom of the deep sea,” says Joeri van Leeuwen. He is an Astron and UvA astronomer and founder of the study. Van Leeuwen and his colleagues hope that radio flashes will be so reliable that they can study the formation of the deep universe.

But not everyone is convinced. “The flashes are fairly clean,” said Jason Hessels, an astronomer at the University of Amsterdam and Astron, who was not involved in the study. “They’re not much affected by stellar winds coming from a partner star; long waves also reached Earth. But there are many differences in the flashes, Which suggests that something in the source is interfering with it. I don’t think the environment is really clean as a lone star. Not that.”