A new study examines for the first time the details of a signal from fast radio bursts (FRBs) to a time scale of a few microseconds, finding that the method can determine the size of the physical space where the signal originates.
Fast radio bursts are intense and strange radio signals, either repetitive, with intervals varying from milliseconds to weeks, or received only once so far, and scientists have tentatively classified them as non-repetitive. Astronomers have yet to fully grasp their nature.
Recently a research group studied a fast radio burst signal that lasts a few milliseconds at a time and analyzed its characteristics in only 3-4 microseconds, calling this the “microstructure” of the fast radio burst signal. They found that the microstructure of these signals contains more details about the objects from which they originate.
They analyzed the repetitive signal FRB180916, which repeats once for 16 days, is very active for 4 of those days, and then quiets down for 12 days before starting the next cycle of signals.
By ‘microstructure,’ we mean that the fast radio burst signal varies in intensity over a small time frame like microseconds,” said study leader Kenzie Nimmo, a doctoral student at the Universiteit van Amsterdam. time scale.”
These patterns, Nimmo said, “effectively constrain the extent of the source region of this fast radio burst and guide the construction of hypothetical models of these signals. In other words, this study finds that the pattern of fast radio burst signals in microscopic time intervals can lead researchers to the size of the physical space of the signal’s source region.
By analyzing the microstructure of FRB 180916, this study found that the area of its source event is only about 1 km in size. At the same time, what the researchers already knew was that the signal came from a location 457 million light years from Earth.
Determining that a signal from such a distant region came from a physical space no more than 1 km in size is what makes the results of this analysis so astounding.
Previous studies had analyzed patterns in the 20 to 30 microsecond time frame, and this study improved the accuracy by a factor of nearly 10. The team said they were also able to analyze the “polarization position angle” of the source, i.e., the details of the signal’s polarized light oscillations. This property will reveal the characteristics of how the source of the fast radio burst signal is rotating and the distance of the signal from the source object. This information will further determine the exact identity of the fast radio burst signal.
From the repetition period of FRB 180916, they suggest that the signal is likely to come from a binary system containing a neutron star rotating in an incoming motion, with another massive star. A neutron star is a dense stellar remnant capable of compressing material with more mass than a sun within a sphere only 12 miles in diameter.
The two objects orbit each other with a 16-day period, and when the two are at their closest proximity within their orbits, the interaction between the two intensifies, resulting in the generation of an enhanced signal – the same period of four days of strong signals observed on Earth.
Finally, Nimmo also suggested that studying the signal structure at a microscopic enough level might reveal that the fast radio burst signals previously classified as “non-repetitive” are also repetitive. “This is important because there is still controversy about whether repetitive and non-repetitive fast radio burst signals are the same or not, and whether they come from different celestial events.”
The study was published March 22 in the journal Nature Astronomy.
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