Object giving off bursts of energy unlike anything known

January 30, 2022

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Astronomers have discovered a strange object giving off regular bursts of energy, unlike anything seen before. Discovered by a team from the International Centre for Radio Astronomy Research (ICRAR), three times per hour the object gives off bursts so powerful they are some of the brightest radio sources in the sky.

“This object was appearing and disappearing over a few hours during our observations. That was completely unexpected. It was kind of spooky for an astronomer because there’s nothing known in the sky that does that,” said lead researcher Natasha Hurley-Walker in a statement. “And it’s really quite close to us — about 4,000 light-years away. It’s in our galactic backyard.”

An artist’s impression of a magnetar. — An artist’s impression of what the object might look like if it’s a magnetar. Magnetars are incredibly magnetic neutron stars, some of which sometimes produce radio emissions. Known magnetars rotate every few seconds, but theoretically, ultra-long period magnetars could rotate much more slowly. ICRAR

The team’s theory is that the object could be a hypothesized object called an ultra-long period magnetar. Magnetars are neutron stars with very powerful magnetic fields which give off bursts of high-energy radiation, but those discovered so far spin much faster and emit pulses every 10 seconds or so. The much slower rate of pulses from this object, at around one every 20 minutes, suggests it must be spinning much more slowly.

Although longer-period magnetars have been predicted, none have been discovered to date. “It’s a type of slowly spinning neutron star that has been predicted to exist theoretically,” Hurley-Walker 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.”

The team is planning to look for signs of similar objects in archival data from the Murchison Widefield Array (MWA) telescope which they used for the initial observations. They are also continuing to observe the object to see if it starts emitting pulses again. “If it does, there are telescopes across the Southern Hemisphere and even in orbit that can point straight to it,” Hurley-Walker said. “More detections will tell astronomers whether this was a rare one-off event or a vast new population we’d never noticed before.”

The research is published in the journal Nature.