‘spooky’ object that releases energy periodically discovered in the Milky Way

Astrophysicist Natasha Hurley-Walker was scanning radio signals over huge swaths of the universe in late 2020 when she and her colleagues stumbled upon something they had never seen before. .

In an area of ​​the sky that has been continuously monitored for 24 hours, scientists have detected the appearance of a mysterious object that emits a huge burst of energy every 20 minutes or so and then disappears for a few minutes. hours later.

Hurley-Walker, an astronomer at Curtin University and the Center for Radio Astronomy Research in Australia, said: “It’s a pretty scary thing for an astronomer because there’s nothing in the sky. do that”. The researchers detailed this finding in a study published Wednesday in the journal Nature magazine.

Observation is known as a radio process, which refers to an object that periodically emits flashes of radio signals, as if it were turning on and off in space.

Occurrences have been seen before – usually events that are very rapid and go off in seconds or milliseconds, or longer pulses lasting many days – but previous radio processes were not detected. appear and disappear within hours, says Hurley-Walker.

More research is needed to figure out what causes the burst of energy, but astronomers think it could be the so-called magnetis a special form of “dead” star with a strong magnetic field.

Hurley-Walker said the prospect of a radio signal repeating in space might lead some to think it was an alien dispatch, but she said the observations span a wide range of frequencies. numbers, which indicates that they are of natural origin and not man-made. signal.

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 Outback Western Australia.

Tyrone O’Doherty, an undergraduate student at Curtin University at the time, found the object by looking at observations of the Milky Way from March 2018 and May 2018 and looking for any any difference. O’Doherty said he did not expect to be able to make such a fascinating discovery.

“It actually feels pretty bizarre to find something like this,” he said Monday at a news conference.

To confirm the discovery, Hurley-Walker sifted through the Murchison Widefield Array’s extensive archive, dating back to 2013, to see if the telescope had picked up any other activity from the object. She discovered that it was turned on for the first part of 2018, emitting 71 radio signals between January and March of that year, before turning off again. As she and her colleagues saw in their own observations, the pulses appeared at regular intervals.

“It’s just once every 18.18 minutes, like the hands of a clock,” she said.

Astronomers have determined that the object is about 4,000 light-years away, and that it is likely a slowly rotating magnet that is somehow converting energy from its magnetic field into light that the telescope detectable radio text. Pinning the details, however, will require observing the object when it becomes active again, or finding similar objects elsewhere in the Milky Way, Hurley-Walker said.

Kiyoshi Masui, an assistant professor of physics at the Massachusetts Institute of Technology who was not involved in the study, called it an “exciting” discovery that demonstrates how much remains to be understood about radio propagation.

“There are all these things waiting to be found,” he said.

Masui’s own research focuses on what is known as fast radio stationare mysterious single pulses of radio waves from other galaxies Astronomers have long been mysterious. Fast radio bursts appear to be random, releasing explosive bursts of energy before disappearing.

It is possible, says Masui, that the two phenomena are related. Magnets are thought to be a possible source of fast radio bursts, but the links are not always clear.

A magnet is a type of dead star, or neutron star, that has burned through its fuel and collapsed into a very dense rotating object with a strong magnetic field. Magnets are usually found only in regions where new stars are born, but fast radio bursts have been detected from stellar nurseries, sometimes in regions where only older stars are present. , Masu said.

In their study, Hurley-Walker and her colleagues found that the newly discovered object appears to rotate much more slowly than other magnetic fields, which could indicate that it has been around for a long time. than other magnets that usually last only a few thousand years.

“If this object is indeed a magnet, it means that at least some types of magnets could last longer than we thought,” Masui said. “That could solve the conundrum of the magnetic field hypothesis for fast radio bursts.”

However, Hurley-Walker said it could also be a whole new type of cosmic object that causes energetic rays. Although the object does not appear to be active at the moment, she plans to continue monitoring the Milky Way with other radio telescopes and X-ray observatories in the hope of finding other objects like it. . Building a catalog of similar occurrences can help researchers understand how they occur.

“Because we didn’t expect this kind of radio emission to happen, the fact that it existed tells us that some kind of extreme physical process must be happening,” she said.