Astronomers at the Canadian Institute for Advanced Research have found that fast radio bursts are likely due to exotic conditions created by strong magnetic fields from neutron stars or black holes and dense ionized gas. The researchers' article was published in the journal Nature. This was announced in a press release on the EurekAlert! Website.
Fast radio bursts (FRB) are radio pulses of unknown origin that last only a few milliseconds. The first fast radio pulse was detected in the 2001 radio telescope in Australia, the data from which was processed only by 2007. Since then, the existence of about 20 such signals has been confirmed. Possible sources were either neutron stars merged with each other, or heavy pulsars (blitzars) turning into a black hole. In addition, some scientists believe that radio bursts are caused by the activities of alien civilizations.
Scientists know of only one source of radio bursts, which emits repetitive pulses. In August 2017, American astronomers using the Green Bank Telescope in Virginia recorded 15 signals with a frequency of 5-8 gigahertz, which came from a dwarf galaxy three billion light years from Earth. However, the source, designated FRB 121102, also emitted radio pulses in 2012 and 2015.
Repetition of signals makes FRB 121102 a convenient object for studying the causes of flares. The researchers analyzed the parameters of the radio emission from the source. In a vacuum, exposure to magnetic fields can lead to the Faraday effect, when the plane of the amplitude of an electromagnetic wave is rotated by a certain angle. By measuring this angle, the scientists concluded that the radio emission passed through a region of space with super-strong magnetic fields.
Such exotic conditions can arise near a supermassive black hole, which exceeds the mass of the Sun by 10-100 million times and generates a powerful magnetic field. Then the direct source of the flare can be a neutron star or plasma influenced by the hole. Another explanation is that FRB 121102 is a magnetized plerion, a nebula fueled by the stellar wind from a pulsar.
According to scientists, the results of the observation indicate that FRBs can arise when supercompact objects interact with extreme magnetic fields. However, it remains to be seen which mechanism is responsible for the formation of fast radio pulses.