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Old 28-06-2019, 11:25 AM
gary
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CSIRO team pinpoint one-off Fast Radio Burst (FRB) using ASKAP

In a story today by Issam Ahmed at AFP, it is reported that a CSIRO team
using the Australian Square Kilometre Array Pathfinder (ASKAP) radio
telescope in Western Australia has managed to pinpoint a Fast Radio
Burst (FRB) to its home galaxy, DES J214425.25?405400.81, about 3.6
billion light years away.

85 FRB's have been detected since they were first discovered in 2007 and they remain a mystery.
In a millisecond they can emit as much energy as the Sun does in 10,000 years.

Most appear to give a one-off burst but some have been repeaters.

Quote:
Originally Posted by Issam Ahmed, AFP
In 2017, astronomers were able to trace the source of a repeating burst, but locating a one-off FRB presented a much more difficult challenge.

Without the benefit of knowing where to look, a team led by Keith Bannister of the Commonwealth Scientific and Industrial Research Organisation (CSIRO) had to devise a new methodology.

"You can think of it as live action replay mode, where we have a computer that's actually looking for the FRB, so it looked through about a billion measurements every second and I tried to find the one that contains an FRB," Bannister told AFP.
Quote:
Originally Posted by Issam Ahmed, AFP
The team then imaged the galaxy with the European Southern Observatory's Very Large Telescope in Chile, and measured its distance with the Keck telescope in Hawaii and the Gemini South telescope in Chile.

While the previously localized FRB 121102 was found to emanate from a dwarf galaxy that was actively forming young stars, the new FRB comes from the outskirts of a massive galaxy with old stars, suggesting a completely different engine is responsible for its creation.

"The first localization inspired lots of modeling based on magnetars formed in the deaths of massive stars," said Law, a model which predicted a number of properties confirmed in 121102.

A magnetar is a highly-magnetized type of neutron star, which are formed by the gravitational collapse of a star not quite massive enough to produce a black hole when it explodes.

But the new location is incompatible with the old theory, suggesting there are multiple channels for forming FRBs.
Quote:
Originally Posted by Issam Ahmed, AFP
The new finding is also exciting for another reason: it could help astronomers probe what lies in the vast spaces between galaxies and bring us a step closer to resolving the "missing matter" problem.

Theoretical calculations have suggested there should be twice the number of atoms that can be seen in the stars, which led astronomers to theorize they must be contained in ionized gases in the vast spaces that separate galaxies.

Just as light splits into different colors as it passes through a prism, radio waves disperse as they encounter matter. In the case of FRBs, higher frequencies arrive first, and lower frequencies arrive later.

This creates a dispersion pattern, and the pattern observed from FRB 180924 matched what astronomers expected from the theory, meaning the intergalactic space does indeed contain the amount of ionized gas that was expected.

Moving forward, the team would like to localize thousands, if not tens of thousands of more FRBs and look at their dispersions, to generate a detailed map of the far reaches of space.

"It's like making a CT scan of this cosmic web," said co-author Ryan Shannon from Swinburne University.

On the missing matter problem, he said: "I think we're on the way to sewing it up. With a few more localized bursts we will be able to nail it."
Their results have been published in a paper in Science.

Story here :-
https://phys.org/news/2019-06-astronomers-history.html

Full paper (free).
K.W. Bannister el al., "A single fast radio burst localized to a massive galaxy at cosmological distance," Science (2019). :-
https://science.sciencemag.org/conte...cience.aaw5903

Last edited by gary; 28-06-2019 at 12:30 PM.
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