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Astronomers have caught 1,652 radio bursts from an unusual source in 47 days

An international team of researchers led by scientists from the Chinese Academy of Sciences, using the Chinese FAST radio telescope with a record 500-meter aperture, studied the source of fast radio bursts FRB 121102 found in 2018 using a neural network and registered the largest set of such events to date — 1652 separate bursts in 47 days, starting from August 29, 2019. An article about this was published in the journal Nature.

In terms of its activity, FRB 121102 surpassed all other known sources of fast radio bursts combined, these data allow us to study for the first time the energy distribution of the signal source and thereby shed light on the main mechanism powering fast radio bursts.

The phenomenon of fast radio bursts has been known since 2007. The first such radio burst was discovered by chance by a group of American scientists led by Duncan Lorimer from West Virginia University, who, in search of signals from pulsars, viewed the results of observations six years ago from the Australian 64-meter Parkes radio telescope. The signal turned out to be very powerful, but short — only a few milliseconds — and was never repeated. Since then, it has been possible to find many more similar events, but it has not been possible to unambiguously link them with anyone phenomenon.

These cosmic explosions can last only one-thousandth of a second while releasing energy comparable to what the Sun emits during the year. One of the most popular theories connects fast radio bursts with magnetars — neutron stars with exceptionally strong magnetic fields. Alternative theories speak either about the birth or, conversely, about the evaporation of black holes or even cosmic strings — artifacts left over from the Big Bang. Perhaps it will not be possible to find a single explanation for all these events.

Only a small part of the sources of fast radio bursts can be localized and have repetitive (but not periodic) signals. FRB 121102 is precisely one of the well-localized repetitive sources. It is associated with an as yet unknown permanent radio source in a dwarf galaxy located 3 billion light-years from Earth. These circumstances give hope that the long-standing cosmic mystery will finally be solved. But FRB 121102 behaves rather strangely so far: 90 days of activity can be replaced by 67 days of calm. During the peak of FRB 121102 activity, 122 events were recorded per hour, which is incomparable with any other source of fast radio bursts. The total energy of this set of pulses was up to 3.8% of what is available to magnets, but the expected periodicity between values of 1 ms and 1000 s was not detected, which greatly reduces the likelihood that the signals originate from a single compact object.

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