by A speck of light that scientists once dismissed as a distant galaxy may actually be the brightest pulsar ever detected outside of the Milky Way.
Named PSR J0523−7125 and located about 160,000 light-years from land in the Large Magellanic Cloud (a satellite galaxy orbiting the Milky Way), the newly defined pulsar is twice as wide as any other pulsar in the region and 10 times brighter than any known pulsar beyond our galaxy. In fact, the object is so large and bright that researchers originally interpreted it as a distant galaxy; however, new research published May 2 in the journal Astrophysical journal letters suggests that this is not the case.
Using the Australian Square Kilometer Array Pathfinder (ASKAP) radio telescope in Western Australia, the study authors peered into space through a special pair of “sunglasses” that block all wavelengths of light except one specific type of light. emission associated with pulsars, the highly magnetized shells of stars. When PSR J0523−7125 appeared bright and clear in the results, the team realized they weren’t looking at a galaxy at all, but rather the throbbing body of a dead star.
“It was an incredible surprise,” said the study’s lead author, Yuanming Wang, an astrophysicist at the Australian Commonwealth Scientific and Industrial Research Organization (CSIRO). said in a statement. “I didn’t expect to find a new pulsar, let alone the brightest one. But with the new telescopes we now have access to, like ASKAP and its sunglasses, it really is possible.”
glasses on
Pulsars are highly magnetized, rapidly spinning remnants of exploded stars. As they rotate, streams of radio waves they burst forth from their poles, pulsing like the beams of a lighthouse as those radio waves head toward Earth.
The radio waves emitted by pulsars are different from many other cosmic light sources in that they can be circularly polarized, meaning the light’s electric field can rotate in a circle as it propagates forward. This unique polarization can provide scientists with a big clue in the tricky game of distinguishing pulsars from other distant light sources. In their new study, the researchers used a computer program to filter out circularly polarized light sources from an ASKAP survey of pulsar candidates.
The team found that the putative galaxy PSR J0523−7125 was emitting circularly polarized light, meaning it is almost certainly a pulsar. And because pulsars are incredibly small, typically packing the mass of a sun into a ball no wider than a city, that means the object must be much closer and much brighter than scientists previously thought. . In fact, if this pulsar is lurking in the nearby Large Magellanic Cloud, as the researchers suspect, then it is the brightest pulsar ever found outside the Milky Way.
That exceptional brightness explains why the object was misidentified as a galaxy after its initial detection, the researchers said. And by filtering out circularly polarized light from future star surveys, researchers may unmask even more unusual pulsars hiding in plain sight.
“We should expect to find more pulsars using this technique,” study co-author Tara Murphy, a radio astronomer at the University of Sydney in Australia, said in the statement. “This is the first time we have been able to systematically and routinely look for the polarization of a pulsar.”
Originally published on Live Science.
