Dec. 2, 2015

A team including astronomers from the University of Toronto has discovered a unique flash of radio energy from space. It is the most recent detection of a type of enigmatic signal known as Fast Radio Bursts. Designated FRB 110523, the burst is unique among FRBs and sheds new light on the nature of these strange cosmic events.
Both their distance and true nature remain mysteries. Since their discovery in 2006, astronomers thought they could be as close as within our own Milky Way Galaxy, or so distant that they came from halfway across the Universe. The new data rules out existing models and sends theorists back to the drawing board.

Astronomers hypothesize that the bursts could come from the birth of black holes, mergers of neutron stars, or flares from magnetars—stars with powerful magnetic fields.
Kiyoshi Masui of University of British Columbia is lead author of a paper to be published this week in Nature that describes the discovery. Co-author Ue-Li Pen is with the Canadian Institute for Theoretical Astrophysics and an associate faculty member of the Dunlap Institute for Astronomy & Astrophysics, U of T.
The observations indicate that previous interpretations of distances and propagation effects were incorrect, ruling out most of the proposed models. Says Masui of the team’s results, “This significantly narrows down the source’s environment and the type of event that triggered the burst.”

The observations also show that the signal passed through a powerful magnetic field on its way to Earth, as well as a cloud of gas within a hundred thousand light-years of the source. These findings suggest the source may be a recent supernova or the interior of a star-forming nebula, and seem to rule out the possibility that they are in galactic nuclei.
Because of their ephemeral nature, FRBs are extremely difficult to observe and FRB 110523 wasn’t found during a real time search of the sky. Rather, the team of astronomers found the signal by sifting through 700 hours of archival data from the National Science Foundation’s Green Bank Telescope as part of a survey initiated by Masui, Pen and others. New analysis techniques developed by this team of cosmologists enabled efficient searches leading to this unique discovery.

Says Pen, “This is the second time the team persevered to overcome the odds to open a new viewpoint of the Universe. The data was originally taken for a 21cm survey which was previously thought impossible and has since led to a new generation of telescopes including CHIME in Canada.”
The 100-meter Green Bank Telescope is the world’s largest fully steerable radio telescope. Its location in the National Radio Quiet Zone and the West Virginia Radio Astronomy Zone protects the incredibly sensitive telescope from unwanted radio interference, enabling it to perform unique observations.

Image: Artist impression of a Fast Radio Burst (FRB) reaching Earth. The colors represent the burst arriving at different radio wavelengths, with long wavelengths (red) arriving several seconds after short wavelengths (blue). This delay is called dispersion and occurs when radio waves travel through cosmic plasma. Credit: Jingchuan Yu, Beijing Planetarium