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| Cosmic radio burst caught red-handed |
Melbourne: Astronomers for the first time seen a 'fast radio burst' – a short, sharp flash of radio waves from an unknown source – happening live.
A mysterious radio signal which may have come from a black hole, a neutron star or even an alien civilisation, has been picked up by astronomers using CSIRO’s 64-m Parkes radio telescope in eastern Australia.
Fast radio bursts, which last only milliseconds, are quick, bright flashes of radio waves from unknown sources in the universe, which emit as much energy as the Sun does in an entire day.
The first one was discovered in 2007 by sifting through old data, and only seven more have been spotted since then.
Exactly what may be causing the signal is hotly debated by scientists. Possibilities range from evaporating black holes to alien communication and merging neutron stars.
“These events are one of the biggest mysteries in the universe,” said Carnegie Observatories’ acting director John Mulchaey.
“Until now, astronomers were not able to catch one of these events in the act.”
Six more bursts, apparently from outside our Galaxy, have now been found with Parkes and a seventh with the Arecibotelescope in Puerto Rico.
"These bursts were generally discovered weeks or months or even more than a decade after they happened! We’re the first to catch one in real time," said Emily Petroff, a PhD candidate co-supervised by CSIRO and by Swinburne University of Technology in Melbourne.
A short, sharp flash of radio waves from an unknown source – happening live
Scientists had been looking for the bursts using twelve telescopes in Australia, California, the Canary Islands, Chile, Germany, Hawaii, and India.
Because the radio waves were ‘caught in the act’ scientists were able to check for other wavelengths such as infrared light, or x-rays to try and work out their source. However they found nothing.
“The fact that we did not see light in other wavelengths eliminates a number of astronomical phenomena that are associated with violent events such as gamma-ray bursts from exploding stars and supernovae, which were otherwise candidates for the burst,” said Daniele Malesani.
But the way that the waves were polarised suggested that it had been near to an object with a large magnetic field.
“The theories are now that the radio wave burst might be linked to a very compact type of object -- such as neutron stars or black holes and the bursts could be connected to collisions or ‘star quakes.’
“Now we know more about what we should be looking for,” says Daniele Malesani, of the University of Copenhagan.
Previous signals indicated that the bursts originated from outside of our Milky Way galaxy.
The team’s data indicates that the burst originated up to 5.5 billion light-years away.
Emily Petroff, a PhD candidate from Swinburne University of Technology in Melbourne, Australia, added: “These bursts were generally discovered weeks or months or even more than a decade after they happened.
“We’re the first to catch one in real time.”
Their work is published in Monthly Notices of the Royal Astronomical Society.