An international team of astronomers has discovered a second rapidly and persistently active radio burst, raising questions about the nature of the mysterious phenomena.
fast radio bursts (FRBs) are intense and brief flashes of radio frequency emissions, lasting in the order of milliseconds. The phenomenon was discovered in 2007 by graduate student David Narkevic and his supervisor Duncan Lorimer. The source of these highly energetic events is a mystery, but clues about their nature are gradually being collected.
The new source, Fast radio burst 20190520B, was detected with the Five Hundred-Meter Aperture Spherical Radio Telescope (FAST) in Guizhou, China, on May 20, 2019 and found in data in November of that year, a new study (opens in new tab)reports.
Follow-up observations of the Jansky very large matrix (VLA) led by Caltech found weaker and more constant radio emissions associated with the FRB, also allowing the Subaru Telescope in Hawaii to locate the source within the shores of a dwarf galaxy about 3 billion light-years from Earth.
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Notably, it is the second repeated FRB discovered to be associated with a persistent radio source (PRS), following the location of FRB 121102 in 2012.
“The big surprise for me was realizing that the new FRB appears to be a perfect ‘twin’ to an earlier discovery,” Casey Law, astronomer at Caltech and co-author who led the VLA program, told Space.com.
“Perhaps some would prefer to say that the first of these associations [between an FRB and radio source] it was a coincidence, because it was hard to explain. Now the second example shows that this is a real and critical part of an FRB’s life.”
The finding raises new questions about the nature of FRBs, such as whether the sources of FRBs evolve over time or, alternatively, whether different types of sources are capable of emitting FRBs.
“One of the main questions in the field of FRBs is whether all sources of FRBs are repeated,” said Di Li of the National Astronomical Observatories of China (NAOC) and leader of the Commensal Radio Astronomy FAST Survey (CRAFTS), which detected FRB 190520B. , Space.com by email. “Personally, I am in favor of an evolutionary picture in which all sources repeat themselves, but the level of activity drops precipitously as the source ages. they could, in this hypothetical evolutionary framework, represent the youth of FRBs, which doesn’t last long.”
Another special feature of FRB 190520B is its scattering measurement, which indicates that its emissions passed through the highest electron density of any FRB before being observed on Earth. This suggests that the FRB is active in a local plasma environment such as that created by a supernovaand is a newly created font.
While providing insights into the environment of FRB 190520B, the wide disparity in scatter measurements with other FRBs calls into question their use as “cosmic measurements” for measuring distances.
Franz Kirsten, a postdoctoral researcher at the Dutch Institute of Radio Astronomy (ASTRON) and Chalmers University in Sweden, who was not involved in the research, told Space.com that an evolutionary path to FRBs is possible, but with just these two sources, it’s hard to say.
“We need to find more and constrain this evolutionary stage model. We really need more at different ages to say that okay, this thing is disappearing all the time,” Kirsten said. “So what would be really nice to see is if these persistent sources are in fact disappearing over time, let’s say 10 to 20 year timescales. If we can say, okay, they’re getting weaker, then certainly is an indication that this is a possibility.”
To accompany this research, co-author Yu Wenfei of the Shanghai Astronomical Observatory told Space.com that the “mechanisms responsible for the extra scatter measurement and near-source environment of such repeated FRBs with a PRS association are the following outstanding issues. and resolve.”
“I’m optimistic that the FRB puzzle will be solved by investigating these extreme FRBs,” Yu said.
Di also sees great value in discovering more repeated FRB sources, as well as trying to get a much better picture of the environments they occur in, for example using the Hubble Space Telescope for follow-up observations.
Cooperation between astronomers and facilities around the world will be crucial in finding, locating and characterizing these mysterious phenomena, as was the case with FRB 190520B.
“This discovery is impossible without international cooperation. FAST made the discovery and only the VLA is able to locate it so efficiently. Each instrument has its strength and we all have a sky”, says Di.
The study (opens in new tab) was published online in the journal Nature today (June 8).
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