There’s a Magnetar In Our Cosmic Backyard

by Jessica Hall

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Astronomers in the Australian outback have discovered something new. Three times an hour, it becomes one of the brightest objects in the sky. The team that discovered it thinks it’s a magnetar — and it’s right in our cosmic backyard.

As the mysterious object rotates, highly polarized or twisted beams of radiation shoot from its poles. Every 18.18 minutes, for 30 to 60 seconds, a beam crosses our line of sight, and the object starts to flash. “It was kind of spooky for an astronomer because there’s nothing known in the sky that does that,” said team leader Dr. Natasha Hurley-Walker in a statement. Slow transients, like a supernova, might happen on a scale of days to months. Faster ones like pulsars flash on and off within milliseconds. “It’s just every 18.18 minutes, like clockwork,” she said.

This image shows the Milky Way as viewed from Earth. The star icon shows the position of the mysterious repeating transient. Credit: Dr Natasha Hurley-Walker (ICRAR/Curtin).

Because of this strangely long interval, Dr. Hurley-Walker said the observations match with predictions of an exotic astrophysical object called an ultra-long period magnetar. “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.”

“Because we didn’t expect this kind of radio emission to be possible,” said Dr. Hurley-Walker, “the fact that it exists tells us that some kind of extreme physical processes must be happening,” she said.

Dr Hurley-Walker is now monitoring the object with the Murchison Widefield Array (MWA) in Western Australia to see if it flashes the porch light again. “If it does,” she said, “there are telescopes across the Southern Hemisphere and even in orbit that can point straight to it.”

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