In 2007 a fast radio burst (FRB) was observed by astronomers for the first time. The source of these phenomena is a mystery since they mostly occur and never repeat themselves. Now a second signal of this type, but repetitive, has been discovered, which offers the possibility of studying them, although it raises new questions.
An international team of astronomers has found the second example of a highly active and repetitive fast radio burst (FRB) with a weaker but persistent compact source of radio emission between the bursts, they report in a press release. The discovery raises new questions about the nature of these mysterious objects and also about their usefulness as tools to study the nature of intergalactic space.
The new source named FRB 20190520B was found by the Five Hundred Meter Aperture Spherical Radio Telescope (FAST) in China in May 2019. Scientists became aware of the data in November 2019 and since then the task has been to track where it comes from and What could it be.
Using the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) and other telescopes to study the object, scientists managed in 2020 to trace the source to a distant galaxy nearly 3 billion light-years from Earth. The VLA studies also revealed that the object constantly emits weaker radio waves between bursts.
FRBs are extremely energetic and as their name says “rapid burst radius”, they only last for milliseconds. They are not common, and most of them come from other galaxies. We usually only detect them once and they never happen again, making it almost impossible to trace them and explain their origin.
According to the researchers, the recent radio burst appears to come from a compact persistent radio source, the nature of which is unknown. Something familiar was discovered in 2012, a famous fast-repeating radio burst called FRB 121102. Are repeaters different from non-repeaters? The differences between these open up the possibility that they are actually from different sources.
“These features make this very much like the first FRB whose position was determined – also by the VLA – back in 2016,” Caltech’s Casey Law said in a statement. That development was a breakthrough, providing the first information about an FRB’s environment and distance. However, its combination of repeated bursts and persistent radio emission between bursts, coming from a compact region, set the 2016 object, called FRB 121102, apart from all other known FRBs, until now.
What is its possible origin? The main candidates for FRB sources are superdense neutron stars left over after a massive star explodes as a supernova, or neutron stars with ultrastrong magnetic fields, called magnetars.
“The field of FRBs is moving very fast right now, with new discoveries appearing every month. However, big questions remain, and this object is giving us challenging clues about those questions,” said Sarah Burke-Spolaor of West Virginia University (WVU).
The findings appear in Nature.
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