The researchers came up with the most accurate time estimates to date regarding the mystery of the so-called “fast radio bursts” (FRBs), which are abrupt pulses from distant cosmic worlds that normally come in strange patterns, thus generating the wildest theories of those about the interaction of stars to alien life.
An international team of astronomers investigated a short-scale, rapid, repeated radio explosion, commonly referred to by the abbreviation FRB, and revealed its “microstructure”, or variable brightness pattern, according to a study published in Nature Astronomy.
The technique recently applied to the probe, by which the team, led by Kenzie Nimmo, a PhD student at the Anton Pannekoek Institute of Astronomy at the University of Amsterdam, studied the explosion signature in extremely tiny periods on her millisecond pulses, “may reveal clues about [FRB] emission techniques ”, says the newspaper.
The researchers were able to obtain this “high resolution” data on the FRB 180916, a mind-boggling repetitive radio pulse that operates on a 16-day cycle, from the European Very Long Baseline Interferometry Network, which consists of advanced telescopes based on four continents.
“The microstructure to which we refer in the [study’s] title is that we see the brightness of the explosion itself vary on microsecond timescales, Nimmo told Vice in an email, adding that these small recurring fluctuations in brightness largely “restrict the size of the FRB emission region”, which has been estimated to cover about one kilometer (0.62 miles).
In other words, the technique of probing FRBs on very short timescales provides a view of the physical space around the enigmatic source of these radio pulses, which, remarkably, is about 457 million light years from our planet, in a totally different galaxy.
Although the distance is relatively close compared to other similar detected explosions, it is extraordinary how Nimmo’s team managed to capture the details of an intergalactic distance.
At this high resolution, the researcher could arrive at the “polarization position angle” (PPA), or the angle at which the polarized light from the explosion oscillates back and forth. This estimate is important to discover details about the rotation of the FRB source and how close the radio emission occurs to its source, which in turn may suggest its possible identity.
Based on their study, the researchers think “the most attractive parent model for FRBs” is neutron stars – extremely dense (superhigh, but relatively small) dead stars, according to Nimmo.
Neutron stars are considered volatile and capable of the type of extreme radio explosion seen in FRBs. For example, a faint burst of radio that occurred in our own galaxy, the Milky Way, has been associated with a special type of highly magnetized neutron star, about 30,000 light years away from Earth.
© Photo: © National Science Foundation / LIGO / Sonoma State University / A. Simonnet
Artistic version of a binary neutron star fusion.
Some models of FRBs suggest that their radio pulses can be traced to the vicinity of a star, that is, its magnetosphere, while others suggest that the emission is the result of some shock wave that occurs far from the source, said Nimmo. The new high-resolution study supports the previous scenario, in which the emission appears in the immediate vicinity of the neutron star, follows from the article.
The repetition periodicity of FRB 180916, in turn, suggests that it may originate in a binary system composed of a rotating neutron star and a massive star that share a 16-day orbital period. When these objects are closer together during orbit, they apparently interact. The latter process amplifies the bursts, causing the 16-day burst cycle, by which it actively fires for four days and remains at rest for 12 subsequent days, the study notes.