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Strange energy bursts seem to be from giant magnetic star scientists have a ‘hard time believing’ exists

It was previously thought that two orbiting stars caused the flares, but a slowly rotating magnetar is the only possibility that fits with observations

Adam Smith
Wednesday 01 September 2021 14:01 BST
(Joeri van Leeuwen)

Scientists may have discovered the source of mysterious, repeating pulses of radio waves that was previously thought to have come from a pair of distant stars.

A hugely powerful cosmic magnetic star is thought to be the source of one set of fast radio bursts (FRBs), which release enormous amounts of energy; but this celestial body does not fit with astronomers’ current models.

"With our current knowledge, it’s very hard to understand how such magnetar [a rare form of neutron star] could exist," Inés Pastor-Marazuela, an astrophysicist at the University of Amsterdam told Space. "But so far, there are no other models that fit our observations."

These particular bursts were first discovered in 2018, pulsing energy every 16 days. These are some of the brightest flashes in the sky but are invisible to the human eye, and last only a thousandth of a second.

This light goes from short-wave ‘bluer’ lengths to ‘redder’, longer wavelengths. It was expected that the bursts should shine only in blue wavelengths, or that the blue wavelengths should be much longer than the red ones. The periodic repetition would also be explained by a pair of stars orbiting each other.

“Strong stellar winds from the companion of the Fast Radio Burst source were expected to let most blue, short-wavelength radio light escape the system. But the redder long-wavelength radio should be blocked more, or even completely,” said Pastor-Marazuela in a release.

What scientists saw, however, were two days of blue radio bursts followed by three days of red ones – making them believe that a slowly rotating magnetar is the source. “It was thrilling to discover that Fast Radio Burst shine at such long wavelengths. After going through immense amounts of data, I had a hard time believing it at first, even though the detection was convincing”, Dr Yogesh Maan of the Netherlands Institute for Radio Astronomy (ASTRON) said.

This finding may help scientists hunt down the universe’s elusive baryonic matter. This is the substance that makes up stars, galaxies, and planets – comprised of particles known as baryons. Astronomers have, strangely, only been able to account for half of the predicted baryonic matter in the universe.

By analysing the times at which the red and blue signals reach Earth, scientists can model how much baryonic matter the waves passed through on their journey. This finding implies that FRBs are “bare”, meaning that they are free of any material (such as an electron cloud) that could interfere with the outbursts.

While there is a vast amount of missing material, its low temperature and sparse displacement throughout the universe makes it challenging to detect.

Researchers have used this technique before using radio telescopes in Australia, and there are hundreds of them in the universe to be investigated.

The research, “Chromatic periodic activity down to 120 MHz in a Fast Radio Burst”, was published in the journal Nature.

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