An international team of astronomers reported today that they had tracked down the location of a so-called fast radio burst (FRB), a mysterious and rarely detected burst of energy from space that appears as a short flash of radio waves to telescopes on Earth.
An artist’s impression of a fast radio burst reaching Earth; the colors represent the burst arriving at different radio wavelengths, with long wavelengths (red) arriving seconds after short wavelengths (blue). Image credit: Jingchuan Yu / Beijing Planetarium.
“Our discovery opens the way to working out what makes these bursts,” said team member Dr. Simon Johnston, an astronomer at CSIRO, Australia, and a co-author of a paper published this week in the journal Nature.
According to astronomers, FRBs are intense bursts of radio emission that have durations of milliseconds and exhibit the characteristic dispersion sweep of radio pulsars.
They emit as much energy in one millisecond as the Sun emits in 10,000 years, but the physical phenomenon that causes them is unknown.
The first FRB was discovered in 2007, although it was actually observed some six years earlier, in archival data from a pulsar survey of the Magellanic Clouds.
While only 16 FRBs have ever been recorded, astronomers believe there could be thousands of such events a day.
“We report the discovery of a fast radio burst, FRB 150418, and the identification of a fading radio transient lasting 6 days after the event, which we use to identify the host galaxy,” Dr. Johnston and co-authors said.
“We measure the galaxy’s redshift to be z = 0.492 (approximately 6 billion light-years away).”
This object, according to the team, is a massive elliptical galaxy, which is very old, well past its prime period for star formation.
“This is not what we expected. It might mean that the FRB resulted from, say, two neutron stars colliding rather than anything to do with recent star birth,” Dr Johnston said.
The astronomers also confirmed that FRBs can be used to find matter in the Universe that had ‘gone missing.’
“Astronomers think the contents of the Universe are 70% dark energy, 25% dark matter and 5% ordinary matter. But when they add up the matter they can see in stars, galaxies and hydrogen gas, they still only find half as much ordinary matter as should be there – the rest has not been seen directly and so has been described as missing.”
Using FRB 150418 as a tool, Dr Johnston and his colleagues were able to ‘weigh’ the Universe, or at least the normal matter it contains.
“The good news is our observations and the model match – we have found the missing matter,” said lead author Dr Evan Keane, an astronomer at the Jodrell Bank Observatory’s Square Kilometre Array Organisation and the Swinburne University of Technology.
“It’s the first time a fast radio burst has been used to conduct a cosmological measurement.”
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E. F. Keane et al. 2016. The host galaxy of a fast radio burst. Nature 530, 453-456; doi: 10.1038/nature17140
