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A second repetitive radio emerges from the depths of space



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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. Image 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, of which so far only one has ever been repeated from the same source.

Scientists in Canada detected a second repetition of FRB Canadian Radio Telescope for 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 on January 9 Nature in two peer-reviewed papers and presented on the same day at the meeting of the American Astronomical Society in Seattle.

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The repetition of FRB is one of 13 observations observed by CHIME in the summer of 2018 over a three-week period. Further FRBs were found in the following weeks.

Evidence of another repeat 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 an astrophysicist at the University of British Columbia (UBC):

So far, there was only one known to repeat FRB. Knowing that there is another indicates that there could be more out there. And with more repeaters and more sources available for study, we can understand these cosmic puzzles – where they come from and what causes them.

  Long half-cylinder network structures with open side up

Canada's CHIME radio telescope in the Okanagan Valley, British Columbia. Image via CHIME.

The discoveries of CHIME were somewhat surprising – most previously found FRBs were at a frequency near 1400 megahertz (MHz), while the observations of the telescope were in the range of 400 to 800 MHz. However, most of the first 13 new bursts were indeed lower, except for the lowest frequencies CHIME could detect. The scientists believe that additional FRBs could be found that are even lower than the minimum of 400 MHz.

What do the new results mean?

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

Regardless of the source of these radio waves, it is interesting to see how wide a spectrum of frequencies 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 underwent the archival data from Pulsar Investigations

As 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 from their environment and are not too scattered to be recognized upon reaching 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 mystery. 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 explains:

CHIME reconstructs Sky's Overhead image 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.

  Starfield with embedded FRB source point

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

Most astronomers are confident that a natural explanation can be 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 be sure that aliens 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 not been enough time to coordinate such long-range teamwork, even if you can imagine a reason!

It would be difficult to understand how aliens could coordinate such powerful radio bursts over such vast distances, but who knows it Occams razors would suspect that FRBs are naturally of natural origin – but to find out what is causing she further observations.

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

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

Source: Source of a second repetitive fast radio burst

About McGill University

  Paul Scott Anderson


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