The telescope’s “sunglasses” show the brightest extragalactic pulsar ever found


Astronomers have discovered that it may be the brightest pulsar in the sky. Despite the intense light, the pulsar has long evaded detection and was detected only by a telescope equipped with space “sunglasses”.

Pulsars are a type of neutron star that emits beams of radiation from its poles, creating pulses of light when these rays wash the Earth. These bright pulses flicker quickly, usually between them for just a few seconds or milliseconds, making them relatively easy to spot in space.

The recently discovered pulsar, labeled PSR J0523−7125, erupts three times per second and is in the Large Magellanic Cloud, a dwarf galaxy orbiting our Milky Way. It also turns out to be 10 times brighter than any other pulsar ever found outside our galaxy, and competes with the brightest of those in it.

But if he is as bright as he has so long avoided detection? Researchers say that this pulsar has an unusual feature that helped it stay hidden – its radiation beams are very wide, which means that the pulses remain “on” much longer than most pulsars. This means that polls will not notice the light, assuming it is a distant background galaxy.

The pulsar was finally found using the ASKAP radio telescope in Australia, which uses a kind of filter that the team describes as sunglasses. Due to their extreme magnetic field, pulsars produce highly polarized light, which for most instruments is indistinguishable from ordinary light. ASKAP, however, can see this.

The pulsar merges with a noisy background without polarized sunglasses (left), but clearly stands out with them (right)

Yuanming Wang

While studying ASKAP data, the researchers noticed a highly polarized object in the Large Magellanic Cloud that changed its brightness over several months. Subsequent observations with other instruments did not show any objects in the X-ray, optical or infrared wavelength range, but finally the MeerKAT radio telescope in South Africa confirmed that it was an unusual pulsar.

“We should expect to find more pulsars with this technique,” said Professor Tara Murphy, lead author of the study. “This is the first time we have been able to systematically and routinely seek pulsar polarization. Due to its unusual properties, this pulsar has been missed by previous studies, despite how bright it is. ”

The study was published in Astrophysical Journal.

Sources: CSIRO, Conversation

The telescope’s “sunglasses” show the brightest extragalactic pulsar ever found

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