Put on a pair of glasses for the starry sky to make hidden celestial bodies visible? A scientific team discovered the brightest pulsar!

On May 3, Nature News released a news: Astronomers have confirmed that an object once thought to be in a distant galaxy is actually the brightest extragalactic pulsar ever.

What is a pulsar? Simply put, a pulsar is a rotating neutron star, but not all rotating neutron stars are pulsars, because the vast majority (almost all) of neutron stars rotate.

A very notable characteristic of neutron stars is that they release powerful radiation from the magnetic poles of the star. The magnetic poles do not coincide with the rotation axis of the pulsar, but are separated by a certain distance. In this way, when the neutron star rotates once, the electromagnetic radiation sweeps across the space like a lighthouse. When this radiation pulse sweeps across the earth, it is captured by the earth's radio telescope, and people discover a new pulsar.

So to be precise, a pulsar is a rotating neutron star whose magnetic energy radiation sweeps across the Earth, becoming a neutron star. Because neutron stars are very small, generally with a radius of about 10 kilometers, it is difficult to detect without this pulse radiation.

Pulsars rotate very fast. The first pulsar was discovered in 1967. The time interval between each two pulses was only 1.337 seconds, which means that this pulsar rotates once every 1.337 seconds. Of all the pulsars discovered in the world, the longest pulse interval is only 11.765735 seconds and the shortest is only 0.0014 seconds.

The pulses of a pulsar are like a human pulse or a clock, repeating over and over again, very accurately and with a very stable period. At first, people were puzzled by this phenomenon and thought it was a signal from aliens, so the first pulsar was called "Little Green Man No. 1".

Later, after scientists' diligent observation and analysis, they determined that this was a rotating neutron star. Pulsars are widely present in the universe, and more than 3,000 have been discovered worldwide. One of the tasks of the "China Sky Eye" (500-meter Aperture Spherical Radio Telescope) built in Guizhou is to search for neutron stars, and more than 500 have been found.

The recently discovered pulsar is quite special, located in the Large Magellanic Cloud, 163,000 light-years away from us. This is a dwarf galaxy, a relatively small galaxy, which is gravitationally bound by the Milky Way and is therefore a satellite galaxy of the Milky Way. It has about 10 billion stars, many of which are supermassive stars, such as R136A1, the most massive star discovered so far.

Because the pulse of this pulsar is unprecedentedly broad and bright, its brightness is at least 10 times that of other pulsars outside the Milky Way, which is completely inconsistent with the pulse profile of a typical pulsar. Therefore, no one has ever considered it to be a pulsar, but rather it was believed to be a distant galaxy.

Because there are too many stars and galaxies in space, and the cores of galaxies also emit powerful radiation pulses, this pulsar is hidden in the densely packed starry sky, and the pulse signals it emits far exceed those of pulsars discovered in the past, so it was ignored by researchers.

The first to suspect and confirm that this was a pulsar were Yuanming Wang, an astrophysicist at the Commonwealth Scientific and Industrial Research Organisation of Australia, and his international team. They used Australia's Square Kilometer Array Pathfinder Telescope to find clues in the data of the "Variables and Slow Transients" survey. Combined with research on some other radio wave sources, they highly suspected that this radio source was not a galaxy, but a neutron star.

The method to finally identify this pulsar is to put a pair of "glasses" on the space. These are not the glasses we usually know, but a set of computer programs. This program is based on the difference between the radiation of pulsars and other celestial bodies, and screens out the light that is not characteristic of pulsars, just like a filter cloth filters out other stray light, so that the pulsar stands out from the light.

Pulsar radiation is usually highly polarized, some of which oscillate in a circular manner, and few other celestial bodies are polarized like this. This procedure only allows light with circularly polarized wavelengths to pass through. It was found that this is the brightest extragalactic pulsar ever discovered, with a pulse width more than twice that of other known pulsars in the Large Magellanic Cloud and a brightness more than 10 times that of discovered pulsars.

From the picture above, we can see that using this program is like wearing a pair of polarized glasses. The starlight in the sky suddenly disappears, and the pulsar is "exposed" from the "impostor" light in the sky.

This set of "glasses" technology has broad application prospects. The brightest pulsar ever was named PSR J0523-7125, and the research results were published in the world-renowned "Astrophysical Journal" on May 5, 2022. Some other telescopes in the world, such as the MeerKAT radio telescope in South Africa, also confirmed their findings.

Among this achievement, scientists are most interested in the "glasses" technology for discovering neutron stars.

"This pulsar, despite being very bright, had been overlooked by studies due to its unusual properties," said Tara Murphy, a radio astronomer at the University of Sydney in Australia and co-author of the paper. "This is the first time we have looked for polarization in a pulsar in a systematic way, and we look forward to discovering more pulsars using this technique."

American radio astronomer Yvette Cendes said that pulsars are transient celestial bodies, and polarization data helps narrow the source of the object, and also shows that this technology has the potential to identify other transients in the future.

I believe that this pair of glasses will continue to mature and bring more useful explorations and inspirations to future astronomical observations. Using this technology, at least the discovery of pulsars will be faster, more numerous, and more accurate. If our Sky Eye also uses this technology, I believe we will be able to discover more pulsars faster.

What do you think? Thanks for reading, and welcome to discuss.

The copyright of Space-Time Communication is original. Infringement and plagiarism are unethical behavior. Please understand and cooperate.