A repeating fast radio burst from an extreme environment



The findings by an international team of astronomers, including Victoria Kaspi and Shriharsh Tendulkar of McGill, appear in the Jan. 11 edition of Nature and are highlighted on the cover of the journal.

A year ago, the astronomers pinpointed the location of the enigmatic fast radio burst (FRB) source named FRB121102 and reported that it lies in a star-forming region of a dwarf galaxy more than 3 billion light years from Earth. The vast distance to the source implies that it releases an enormous amount of energy in each burst – roughly as much energy in a single millisecond as the Sun releases in an entire day.

Now, using data from the Arecibo Observatory (Puerto Rico) and the Green Bank Telescope (West Virginia), the researchers have shown that the radio bursts from FRB121102 are highly polarized. The behaviour of this polarized emission enables scientists to probe the source’s environment in a new way.

Twisted polarization

When polarized radio waves pass through a region with a magnetic field, the polarization gets “twisted” by an effect known as Faraday rotation: the stronger the magnetic field, the greater the twisting. The amount of twisting observed in FRB121102’s radio bursts is among the largest ever measured in a radio source, leading the researchers to conclude that the bursts are passing through an extraordinarily strong magnetic field in a dense plasma.

Vicky Kaspi, Director of the McGill Space Institute. / Photo: Owen Egan


One possible explanation for the hugely magnetized environment is that FRB121102 is located close to a massive black hole in its host galaxy.  Such highly magnetized plasmas have so far been seen only near the center of the Milky Way, which has its own massive black hole. But the authors also speculate that the twisting of the radio bursts could be explained if FRB121102 is located in a powerful nebula (an interstellar cloud of gas and dust) or amid the remains of a dead star.


New telescopes could provide answers



Read the study online

Click on the thumbnail below to get more information on the Fast Radio Bursts and the CHIME telescope