Mysterious Cosmic Radio Burst Caught In Real Time

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For the first time ever, astronomers have caught a curious cosmological phenomenon in the act—an immense but fleeting flash of radio waves emanating from an unknown source in the universe. These dramatic eruptions, which are called fast radio bursts (FRBs), are poorly understood, but the latest discovery could finally help scientists understand what they are and where they originate from.

FRBs are extremely powerful events capable of spewing out as much energy as our sun does in hundreds of thousands of years, but they only last a few milliseconds. Since their discovery back in 2007, when they were identified from archival Parkes Telescope data, a further seven bursts have been recorded from two telescopes, one in Australia and one in Puerto Rico. However, they were only ever observed weeks or even years after the actual event occurred.

Determined to catch one in the act, scientists developed a technique that would allow them to actually search for these events so that they can be recorded in real time, rather than relying on old data. Now, thanks to this method, a team of researchers has finally managed to capture one of these bursts as it occurred. 

The FRB was detected on May 14, 2014, by astronomer Emily Petroff and colleagues who were using the Parkes radio telescope. The radio waves seemed to be coming from a source approximately 5.5 billion light-years from Earth, near the constellation Aquarius. Twelve other telescopes, both ground-based and in space, were then directed towards the source over the next few hours, enabling the researchers to make observations in a range of different wavelengths, including visible light, UV and X-ray. They hoped that this data might offer some clues on the origin of the burst, but no afterglow was observed.

While this meant that the source could not be identified, the absence of data from other wavelengths did offer some insight because it helped the scientists eliminate a couple of candidates, including gamma-ray bursts and supernovae. Furthermore, the Parkes data yielded more clues about the event because it revealed that the waves were circularly polarized. Polarization describes the orientation of wave oscillation; circularly polarized waves vibrate in two planes, whereas the oscillations of linearly polarized waves are confined to one. According to the researchers, this suggests that there could be a magnetic field near the source, although they say the measurements are difficult to interpret.

Although the researchers haven’t managed to associate the burst with any particular events, they hypothesize that it could have been connected with an extremely compact object, such as a neutron star or black hole. Now that the scientists have a better idea of what to look for, hopefully more of these events can be observed in real-time so that we can eventually understand their progenitors and origins. 

[Via University of Copenhagen, New Scientist, Monthly Notices of the Royal Astronomical Society and Earthsky]

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