Astrophysicist Natasha Hurley-Walker was scanning radio signals across vast regions of the universe in late 2020 when she and her colleagues noticed something they had never seen before.
In a part of the sky continuously monitored for more than 24 hours, scientists detected the presence of a mysterious object that emits a giant burst of energy every 20 minutes and then disappears several hours later.
“It was scary for an astronomer because there is nothing in the sky that does this,” Hurley-Walker, an astronomer at Curtin University and of the International Center for Radio Astronomy Research in Australia, said in a statement. Researchers detailed the finding in a study published Wednesday journal nature,
The observation is what is known as a radio transient, which refers to an object that periodically releases brief flashes of radio signals, as if it is going on and off in space.
Events have been observed before – usually as very rapid events that flash on and off within seconds or milliseconds, or as long pulses of the past – but radio transistors have been shown to appear and disappear within the first few hours. Didn’t know, Hurley-Walker said.
More research is needed to find out what causes the burst of energy, but astronomers think it may be a so-called magnetarwhich is a special type of “dead” star with an ultrastrong magnetic field.
Hurley-Walker said that the possibility of a radio signal repeating in space may cause some people to think it is a dispatch from aliens, but added that the observations are spread over a wide range of frequencies, which indicates That they have a natural origin and some are not artificial indicate.
The search began in 2020, when Hurley-Walker assembled a team to map radio waves in the universe using data collected in 2018 by the Murchison Widefield Array, a radio telescope in the Western Australian outback.
Tyrone O’Doherty, a graduate student at Curtin University at the time, found the object by looking at Milky Way observations from March 2018 and May 2018 and searching for any differences. O’Doherty said he didn’t expect such a fascinating discovery.
“To find something like this seems really quite real,” he told a news briefing on Monday.
To confirm the finding, Hurley-Walker sifted through the extensive archives of the Murchison Widefield Array, which spanned 2013, to see if the telescope had picked up any other activity from the object. He found that it switched on in the first half of 2018, emitting 71 flashes of radio signal from January to March of that year before it was turned off again. As he and his colleagues observed in their own observations, the pulses came at regular intervals.
“It’s like clockwork every 18.18 minutes,” she said.
Astronomers determined that the object is about 4,000 light-years away and is likely to be a slowly rotating magnet that is somehow converting energy from its magnetic field into light that can be detected by radio telescopes. Is. Hurley-Walker said, however, that in order to narrow down the details, the object would need to be observed if the object was reactivated or to find similar objects elsewhere in the galaxy.
Kiyoshi Masui, an assistant professor of physics at the Massachusetts Institute of Technology who was not involved in the research, called it an “exciting” discovery that shows how much remains to be understood about radio transistors.
“There’s all this stuff out there just waiting to be found,” he said.
Masui’s own research focuses on what is known as loud radio burstwhich are mysterious single pulses of radio waves from other galaxies have long been mysterious astronomers, Rapid radio bursts that occur randomly, form rapid bursts of energy before disappearing.
It is possible, Masui said, that the two incidents are related. Magnetars are thought to be a potential source of fast radio bursts, but the links are not always clear.
Magnetars are a type of dead star, or neutron star, that has burned off all its fuel and collapsed into a very dense spinning object with a powerful magnetic field. Magnetars are usually only found in regions where new stars are being born, but fast radio bursts have been detected from stellar nurseries, sometimes in regions where only old stars are, Masui said.
In their study, Hurley-Walker and her colleagues found that the newly discovered object appears to spin much slower than other magnets, which may indicate that it is more alive than other magnets that typically only last for a few thousand years.
“If this object is, in fact, a magnet, it could mean that at least some types of magnets may live longer than we thought,” Masui said. “This may resolve the fork in favor of the magnetar hypothesis for fast radio bursts.”
Still, Hurley-Walker said it could also be an entirely new type of cosmic object that causes flashes of energy. Although the object appears to be inactive at this time, she plans to continue monitoring the galaxy with other radio telescopes and X-ray observatories to find others. Creating a list of similar events can help researchers better understand how they formed.
“Since we did not expect such radio emission to be possible, the fact that it exists tells us that some kind of extreme physical processes must be taking place,” she said.