A team of radio wave mappers discovered something that is unusual. It releases a huge burst energy three times per hour and is unlike anything else astronomers have ever seen.
It could have been a neutron star, or a white dwarf. These are collapsing cores of stars with a powerful magnetic field.
The strange object spins in space and emits a beam radiation that crosses our line-of-sight. It is also one of the brightest radio sources, for about a minute in twenty.
The team that discovered the phenomenon was led by Dr Natasha Hurley Walker, an astronomer from Curtin University.
She said, “That was completely unexpected. It was kind of spooky for an astronomer because there’s nothing known in the sky that does that.
“And it’s really quite close to us—about 4000 lightyears away. It’s in our galactic backyard.”
Tyrone O’Doherty, Curtin University Honours Student, discovered the object using the Murchison Widefield Array telescope (MWA), in outback Western Australia. He also used a new technique he invented.
“It’s exciting that the source I identified last year has turned out to be such a peculiar object,” said Mr O’Doherty, who is now studying for a PhD at Curtin.
“The MWA’s wide field of view and extreme sensitivity are perfect for surveying the entire sky and detecting the unexpected.”
Astronomers aren’t unfamiliar with objects that can turn on or off in the Universe. They call them “transients”.
Gemma Anderson, ICRAR-Curtin’s astrophysicist, said that transients are watching the death of a huge star or the activity of its remnants.
“Slow transients”–similar to supernovae–might appear in a matter of days, and then disappear after a few weeks.
“Fast Transients”–like a neutron star called an pulsar- flutter on and off in milliseconds to seconds.
Dr Anderson stated that it was very strange to find something that turns on for just a moment.
She claimed that the mysterious object, which was smaller than the Sun and brighter than the Sun, emitted radio waves with high-polarization. This suggests that it had a strong magnetic field.
Dr Hurley-Walker stated that the observations correspond to a predicted object in the astrophysical field called an “ultra-long-period magnetar”.
She said,
“It’s a type of slowly spinning neutron star that has been predicted to exist theoretically,” she said.
“But nobody expected to directly detect one like this because we didn’t expect them to be so bright.
“Somehow it’s converting magnetic energy to radio waves much more effectively than anything we’ve seen before.”
Dr Hurley-Walker monitors the object using the MWA to determine if it switches on again.
She said, “If it does, there are telescopes across the Southern Hemisphere and even in orbit that can point straight to it,”
Dr Hurley-Walker will continue to look for these rare objects in the extensive archives of the MWA.
She said that “More detections will tell astronomers whether this was a rare one-off event or a vast new population we’d never noticed before,”
Steven Tingay, MWA Director, said that the telescope was a precursor instrument to the Square Kilometre Array, a global initiative to create the largest radio telescopes anywhere in the world.
“Key to finding this object, and studying its detailed properties, is the fact that we have been able to collect and store all the data the MWA produces for almost the last decade at the Pawsey Research Supercomputing Centre. Being able to look back through such a massive dataset when you find an object is pretty unique in astronomy,” he said.
“There are, no doubt, many more gems to be discovered by the MWA and the SKA in coming years.”
Source: https://www.icrar.org/