Mysterious cosmic signals have circular polarization

(ORDO NEWS) — Scientists at the National Astronomical Observatory of the Chinese Academy of Sciences (NAOC) have for the first time detected the circular polarization of electromagnetic radiation, the source of which is repetitive fast radio bursts.

The results of the study, point to the most likely source of flares – the magnetic field of neutron stars.

Fast radio bursts (FRB) occur within a few milliseconds and are accompanied by the release into space of a huge amount of energy – such as the Sun emits for several tens of thousands of years.

Researchers have linked this phenomenon to supernova explosions, neutron star collisions, active black holes or magnetars, but the exact nature of the phenomenon remains a mystery.

Since 2007, when the first FRBs were discovered, more than 600 burst sources have been discovered, most of which were single. Less than five percent of all FRBs recur, and about 10 of them are permanently active.

In single FRBs, two types of radio wave polarization have already been found – circular and linear.

With linear polarization, the vector of the electric field of electromagnetic radiation oscillates in one plane, and with circular polarization it describes a circle.

Only one repeating FRB was found to be circularly polarized, but is not active.

Through a systematic analysis of FAST data, the researchers found circular polarization in less than five percent of the bursts from the repeating sources FRB20121102A and FRB20190520B, the latter of which is a permanently active source.

It is assumed that the conditions for the creation of circular polarization in repetitive FRBs should be more rare, however, the results of the observation indicate that circular polarization may be a common feature of fast radio bursts that occurs periodically.

Polarization is a fundamental property of FRBs and carries important information about the emission mechanisms and surrounding media of the flare source.

The observed circular polarization may occur in the magnetosphere of magnetars, neutron stars with extremely strong magnetic fields, which many studies indicate are the most likely source of FRBs.

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