Astronomers have discovered the brightest pulsar outside our Galaxy

(ORDO NEWS) — Scientists have discovered the brightest pulsar ever observed outside the Milky Way, revealing the true nature of a distant, luminous object previously thought to be a distant galaxy.

Pulsars are incredibly dense neutron stars that emit beams of electromagnetic radiation from their poles.

Due to the fact that these objects rotate rapidly, their high-energy radiation looks like short periodic pulses when viewed from other points in space, like a space beacon periodically flickering in the distance.

More than 2,000 pulsars have been discovered since their discovery in the 1960s by Irish astrophysicist Jocelyn Bell, but the vast majority of these shiny, spinning objects are inside our own galaxy.

Astronomers have discovered the brightest pulsar outside our Galaxy 2

The newly found pulsar, named PSR J0523-7125, is a much rarer discovery of an extragalactic pulsar located far outside the Milky Way, in this case in the Large Magellanic Cloud.

PSR J0523-7125 was discovered by scientists using the Australian Square Kilometer Array Pathfinder (ASKAP) radio telescope in Australia. The find was made possible by scanning the sky for polarized pulsar radiation, a method the researchers compare to the astronomical equivalent of wearing polarized sunglasses.

“It was an amazing surprise,” explains astrophysicist Yuanming Wang of the Australian CSIRO, PhD at the University of Sydney and first author of the new study PSR J0523-7125.

“I didn’t expect to find a new pulsar, much less a bright one. But with the new telescopes we now have access to, like ASKAP and its sunglasses, it’s really possible.”

According to the researchers, PSR J0523-7125 is about 10 times brighter than any other extragalactic pulsars observed before. So why hasn’t it been noticed until now?

Astronomers have discovered the brightest pulsar outside our Galaxy 3

The answer has to do with how pulsars are detected. Traditional search procedures for pulsars are aimed at searching for periodic pulses – a beacon-like flickering effect when the pulsar emits radiation in short, observable bursts.

But astronomers have to turn to other ways to detect more elusive pulsars that exhibit less predictable periodicity or other ambiguous characteristics in their emission.

“Anomalous pulsars, such as binary systems with a short orbital period or highly scattered objects, are more difficult to detect,” the researchers write in their new paper.

In such cases, one possible workaround is to look for signs of circularly polarized light emitted by objects.

To date, only a couple of large-scale studies capable of capturing circularly polarized radiation have been carried out, one of which was performed by the ASKAP array.

In a project called VAST, the researchers filtered the ASKAP data in search of variable and transient sources of light-emitting phenomena. They identified PSR J0523-7125 as a pulsar, confirming the discovery with follow-up observations from South Africa’s MeerKAT radio telescope and CSIRO Parkes observatory in Australia.

“We should expect to find more pulsars with this technique,” explains senior author and astrophysicist Tara Murphy of the University of Sydney.

“This is the first time we have been able to systematically and routinely search for the polarization of a pulsar.”

According to the researchers, PSR J0523-7125 exceeds previous theoretical luminosity limits for the expected brightness of pulsars in the Large Magellanic Cloud, showing that their brightness is on par with objects observed in the Milky Way.

While extragalactic pulsars are still a relative rarity, our ability to detect them – and other types of pulsars that are hard to find with conventional methods – should only increase from now on, thanks to the growing availability of large-scale radio continuum studies and future telescopes such as the upcoming Square Kilometer Array project. which is being built in South Africa.

“With improved instruments in the Square Kilometer Array era, instantaneous large fields of view and high sensitivity will become even more common, leading to the detection of a large number of radio sources across the sky,” the researchers explain.

“Advanced next-generation radio telescopes and a growing number of large-scale, multiwavelength surveys will bring large amounts of data with high sensitivity and resolution, giving us an unprecedented opportunity to identify more pulsars (even for extragalactic pulsars farther than the Magellanic Clouds).”

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