Astronomers find a new twist to mysterious radio signals from space
Incredibly powerful but gone in a flash, mysterious signals known as Fast Radio Bursts (FRBs) are regularly detected in all corners of the sky. A repeating signal known as FRB 121102 was already the weirdest one out there, but now an international team of astronomers has found that this oddball is even odder than previously thought. The radio waves from FRB 121102 are being "twisted" to an extreme degree, indicating that highly-magnetized plasma could be interfering.
FRBs – strange flashes of radio signals that last just milliseconds – are a pretty new phenomenon. They were first spotted in 2007 as an anomaly in archival data, and weren't detected live until 2015. Normally, FRBs are a one-and-done deal, but FRB 121102 bucks the trend, pulsing dozens of times over the years and getting particularly chatty for a few hours back in August.
While we still don't know what's giving off those signals, 121102's regularity helped astronomers figure out that the bursts are coming from a dwarf galaxy some three billion light-years away. And according to the new study, the source (whatever it is) seems to be in a rough neighborhood.
Using data gathered by the Arecibo Observatory in Puerto Rico and the Green Bank Telescope in the US, the astronomers found that FRB 121102's emissions are not only highly polarized, but they're being twisted through an effect known as Faraday rotation. This physics phenomenon is caused by magnetic fields, and in this case, the intense degree of the twisting indicates the signals are passing through a high magnetic field in dense plasma.
To explain this much twisting, the researchers suggest that the source of the signals could be very close to a massive black hole, hiding inside a dense nebula or sitting amongst the remnants of a star gone supernova. The new find could go a long way towards finally identifying what kind of objects could be giving off these FRBs.
"We estimate the magnetic field and gas density surrounding the blast source, and we can link them, for example, with a model involving a young magnetar – a neutron star with an especially large magnetic field – to the central engine that produces the bursts," says James Cordes, an author of the study.
The research was published in the journal Nature.