Two international groups of astronomers have published new data on the famous fast radio burst FRB20180916B, in which low-frequency radiation, uncharacteristic of the phenomenon, was unexpectedly found. The results, published in the Astrophysical Journal Letters and Nature Astronomy, reveal the possible nature of the burst source. The research is summarized in a press release on Phys.org.
FRB was observed with a European network of LOFAR radio telescopes tuned to a range of 110 to 188 megahertz, which is the lowest frequency that the antennas could receive. Scientists managed to capture 18 bursts, although FRBs usually emit radio waves at high frequencies. Thus, the source broke the record for low frequencies, although astronomers suspect that it may emit even lower frequency radio waves.
The low-frequency bursts came later than the high-frequency radio emission. This periodicity indicates that the source of FRB20180916B is a binary system, one of the components of which is a neutron star. Another group of scientists observed that radio bursts have a microstructure, and the radiation is 80 percent linearly polarized. A logical explanation for this variation is the “dancing” magnetosphere of a neutron star. This, in turn, makes it possible to exclude the scenario in which radiation arises at a large distance from the object due to relativistic shock waves created by particles accelerated by the magnetic field of a neutron star and interacting with the interstellar medium.
FRB20180916B, found in 2018, is 500 million light years away, which is close enough for a source of massive amounts of energy. Radio bursts are periodic in nature: they repeat every 16 days, and radiation is emitted over four days with a period of relative rest of 12 days. This predictability makes it a convenient subject for research.
Fast radio bursts occur within a few milliseconds and are accompanied by the release into space of a huge amount of energy – the kind that the Sun has emitted over several tens of thousands of years. Most researchers assume that this mysterious phenomenon has natural causes, for example, supernova explosions, collisions of neutron stars, active black holes or magnetars. However, there is an exotic hypothesis linking FRB to technologically advanced civilizations.
