Mysterious radio flashes: FRB's place of origin localized with extreme precision
Astronomy has been puzzling over fast radio bursts for years. Now such a radio burst has been traced back to its origin with unprecedented precision.
Artist's impression of a magnetar, a neutron star with a particularly strong magnetic field
(Image: NASAs Goddard Space Flight Center/Chris Smith (USRA))
A particularly high-energy radio flash observed two years ago had its origin in the immediate vicinity of a rotating neutron star, in the middle of its extremely strong magnetic field. A research team from the USA has determined this and achieved a localization with unprecedented precision using a new method. They have now added another piece of the puzzle to the explanation of the mysterious fast radio bursts (FRB) that have puzzled astronomers for years.
Treacherous flickering
As the research team from the Massachusetts Institute of Technology explains, the FRB 20221022A radio burst under investigation was a very typical FRB. It was discovered with the Canadian radio telescope CHIME. A signal lasting around two milliseconds was observed. The team examined the differences in brightness detected in this signal for evidence of so-called scintillation. This is the flickering known from stars, which is caused by refraction of the signal somewhere along its path – such as the Earth's atmosphere.
Along the way, the team was able to determine that the extremely high-energy and highly polarized signal was partly refracted by gas in the original galaxy. This acted as a kind of natural lens through which the point of origin could be localized with immense precision. It must be less than 10,000 kilometers away from a rotating neutron star in the magnetosphere. However, because the star is 200 million light years away from us, this localization corresponds to the measurement of a DNA helix two nanometres in size, which is as far away as the moon.
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Close to solving the mystery?
The findings now presented in the scientific journal Nature confirm hypotheses that had assumed this origin to be very close to neutron stars, writes the team. The counter-argument had been that the conditions there are too extreme. After all, the magnetic fields there are at the limit of what is possible in the universe. Not even atoms could exist there. But now we know that energy can still escape from there in such large quantities that we can measure it "halfway across the universe".
The team does not comment on the process that could be responsible for the formation of the FRB there. Just a few weeks ago, another research group explained that the radio flashes could be due to interstellar celestial bodies colliding with neutron stars. FRBs have been discovered since 2007 and there has been much speculation about their origin. Both papers suggest that research may be getting closer to one or more answers.
(mho)
