SETI project listens in on fast radio bursts
Are fast radio bursts caused by neutron stars – or aliens? New observations of FRB 121102 hope to reveal the origins of these energetic eruptions.
The Breakthrough Listen project is helping to uncover the source of fast radio bursts, extreme and unusual bursts of energy.
The team from Breakthrough Listen, an initiative listening out for signs of extra-terrestrial intelligence, were part of a recent study into the mysterious eruptions of radio waves, which release as much energy in a millisecond as the Sun does in an entire day.
When fast radio bursts (FRBs) were first seen in 2007, astronomers were astounded by the intensity of the bursts, and are still uncertain about what could be creating that much energy.
Astronomers have made several suggestions as to their origins – ranging from neutron stars to highly advanced alien civilisations – and have been studying the phenomena for the last decade looking for clues to the culprit.
The Breathrough Listen group turned the Green Bank Telescope towards FRB 121102, a highly unusual FRB that has been observed erupting over 200 times since it was first found a year ago.
All other known FRBs have only been seen erupting once.
Together with observations by a team from the Netherlands using the Arecibo Observatory the group discovered that the radio signals from the FRB are not only highly polarised, but that this polarisation has been twisted.
This suggests the waves passed through an exceptionally strong magnetic field.
“The only known sources in the Milky Way [whose light is] twisted as much as FRB 121102 are in the galactic centre, which is a dynamic region near a massive black hole,” says Daniele Michilli from the University of Amsterdam.
“Maybe FRB 121102 is in a similar environment in its host galaxy. However, the twisting of the radio bursts could also be explained if the source is located in a powerful nebula or supernova remnant.”
The observations lend weight to the idea that FRBs are created by neutron stars, though how they produce such intense bursts of energy is unknown.
Both teams will continue to monitor the FRB to see how it changes over time.
“With these observations we hope to distinguish between the two competing hypotheses of a neutron star either near a black hole or embedded in a powerful nebula,” says Jason Hessels from the University of Amsterdam.
Another possibility, albeit a remote one, is that the bursts are signs of intelligent life elsewhere in the Universe and a potential answer to the question as to whether we will find life beyond Earth.
“At this point we don’t really know the mechanism. There are many questions, such as, how can a rotating neutron star produce the high amount of energy typical of an FRB? We cannot rule out completely the ET hypothesis for the FRBs in general,” says Vishal Gajjar of Breakthrough Listen and the Berkley SETI Research Center.