Astronomers watching a fast-radio burst flashing from more than 3 billion light-years away say that its source lies in an extreme environment with a powerful magnetic field -- perhaps a supermassive black hole, or the remains of a supernova.
The findings about the phenomenon known as FRB 121102, described in the journal Nature and at the American Astronomical Society meeting outside Washington, hint that this mysterious source of powerful radio waves whose origin has puzzled scientists for years may finally be revealing its secrets.
Since their discovery in 2007 from older archived data, fast-radio bursts have confounded astronomers. These bursts last only milliseconds, shorter than the blink of an eye, but in that tiny moment they are incredibly bright, a sign that whatever caused them was very powerful.
"It's some sort of extreme physics that causes this emission and so the goal is to understand that," study coauthor Betsey Adams of ASTRON, the Netherlands Institute for Radio Astronomy, said at a briefing Wednesday.
The problem is that these bursts each only happen once -- leading scientists to suspect that these were cataclysmic, death-throe explosions. So even if a telescope is lucky enough to catch one in the act of going off, there no way to go back to the same source for more detailed measurements.
FRB 121102, sitting about 3 billion light-years away in a dwarf galaxy, was different. Since its discovery in 2012 it has repeatedly sent out flashes of radio waves, allowing researchers to train their telescopes on it to learn more about its origins.
"We know of thirty sources of fast radio bursts, and this is the only one we've ever seen that repeats," senior author Jason Hessels, an astrophysicist at the University of Amsterdam and ASTRON, said in an interview.
Having now observed more than 100 flashes from this single source over the last few years, researchers haven't picked up a pattern to the bursts yet -- aside from the fact that they often seemed to be clustered in time, instead of evenly spaced apart.
Because of the extremely short, repeated bursts, the source was thought to be a kind of neutron star: either a pulsar (which spins very fast) or a magnetar (which spins but also has an extra strong magnetic field). Because it seems to sit in a star-forming region of its host galaxy, the scientists think FRB 121102 is linked to stellar birth or death.
For this paper, the scientists wanted to figure out more about the environment around this source. Using data from the Arecibo Observatory in Puerto Rico and the Green Bank Telescope in West Virginia, the scientists looked at the polarization of the light: how much it's been distorted in specific ways. They found that radio waves have been twisted by a magnetic field -- an extremely powerful one, judging from the degree of contortion.