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Lightning line, with a sharp peak, from a galaxy to telescopes on Earth, not to scale

Artistic concept of a fast radio burst from a distant galaxy. Picture via Danielle Futselaar.

Fast Radio Bursts (FRBs) are one of the most puzzling astrophysical discoveries of recent years. They are strong but brief impulses from radio waves that seem to come from galaxies billions of light-years away. Scientists do not yet know what causes them, but they are finding more and more clues as they continue to investigate. One oddity was that of more than 60 FRBs found so far, of which only one was repeated from the same source – until now.

Scientists in Canada discovered one second repetition of FRB using the Canadian Hydrogen Intensity Mapping Experiment (CHIME) in the Okanagan Valley, British Columbia. It was reported by McGill University on January 9, 2019. The new findings were also published in two peer-reviewed papers nature presented on January 9 and the same day at the meeting of the American Astronomical Society in Seattle.

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The repetitive FRB is one of 13 observed by CHIME in the summer of 2018 over a period of three weeks. In the following weeks, further FRBs were found.

Recognition of another repetitive FRB is exciting, as they generally appear to be relatively rare among FRBs. The first was watched in 2015 by the Arecibo radio telescope in Puerto Rico. Ingrid Stairs, a member of the CHIME team and astrophysicist at the University of British Columbia (UBC):

So far, only a single FRB was known. Knowing that there is another indicates that there could be more out there. With more repeaters and more sources available for learning, we can understand these cosmic puzzles – where they come from and what causes them.

Long half cylinder net structures with open side up

Canada's CHIME Radio Telescope in the Okanagan Valley in British Columbia. Picture about CHIME.

The discovery by CHIME was somewhat surprising – most of the FRBs found were at a frequency near 1400 megahertz (MHz), while the observations of the telescope ranged from 400 to 800 MHz. However, most of the first 13 new bursts were indeed lower, except for the lowest frequencies CHIME could detect. Scientists believe additional FRBs could be found even lower as the minimum of 400 MHz.

What do the new results mean?

Whatever the cause of FRBs, it is something that has not been seen before. The theories ranged from exotic phenomena with neutron stars or black holes to aliens. As noted by Arun Naidu of McGill University:

Whatever the source of these radio waves, it is interesting to see how wide a frequency range can be. There are some models where the source itself can not produce anything below a certain frequency.

The first FRB – FRB 121102 – was discovered in 2007 by Duncan Lorimer and his student David Narkevic when they searched the Archive Pulsar Survey data.

Tom Landecker, a CHIME team member of the National Research Council of Canada, added:

[We now know] The sources can produce low frequency radio waves, and these low frequency waves can escape their environment and are not too scattered to be detected by the earth. That tells us something about the environments and the sources. We did not solve the problem, but there are a few more pieces of the puzzle.

According to Kendrick Smith, a cosmologist at the Perimeter Institute of Theoretical Physics in Waterloo, Ontario:

FRBs were an unexpected puzzle. In astrophysics, there are not so many qualitative mysteries. Explaining her nature has become one of the biggest unsolved problems in astrophysics in recent years.

CHIME is a unique radio telescope designed and built by Canadian astronomers, Smith explained:

CHIME reconstructs the image of the sky above the sky by processing the radio signals recorded by thousands of antennas with a large signal processing system. CHIME's signal processing system is the largest telescope in the world, enabling simultaneous search in large sky areas.

Insertion starfield shows the FRB source point

The first FRB – FRB 121102 – was discovered in 2007. This visible light image shows its host galaxy. Picture about Gemini Observatory / AURA / NSF / NRC.

Most astronomers are pretty confident that a natural explanation is found because FRBs have properties that make a smart source difficult. One problem, as explained by Seth Shostak, a senior astronomer at the SETI Institute, is that they seem to come from all over the sky, galaxies separated by billions of light-years.

But you can bet that extraterrestrials are not the cause of FRBs. Why? The Bursters are seen all over the world, that's why. The same kind of signal comes from galaxies, which are generally separated by billions of light-years. So how can aliens organize so much of the universe that they emit the same kind of signal? Since the Big Bang, there has hardly been enough time to coordinate such long-range teamwork, even if you can find a reason!

It's hard to figure out how aliens could coordinate such powerful radios over such long distances, but who knows? Occam's razor would suggest that FRB are most likely of natural origin is Cause further observations.

Conclusion: FRBs are an exotic phenomenon, regardless of what causes them specifically, and thanks to new observations from telescopes like CHIME, scientists are one step closer to solving this fascinating puzzle.

Source: Observations of fast radio bursts at frequencies up to 400 megahertz

Source: The source of a second repetitive fast burst of radio

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Paul Scott Anderson