This mysterious celestial body emits an "extreme" radio signal every 18 minutes

This mysterious celestial body emits an “extreme” radio signal every 18 minutes

Researchers have spotted a mysterious radio signal, the particular strength and periodicity of which suggests the presence of a new type of celestial body.

To uncover the secrets of the cosmos, astronomers don’t just send various probes and telescopes there; they also devote a good part of their resources to listening at the gates of interstellar space. They thus hope that one of their instruments will end up falling on an interesting element. This is what happened to researchers from the International Center for Radio Astronomy Research (ICRAR), who made a very mysterious discovery.

They picked up a radio signal of such regularity as to make the most prestigious Swiss watchmakers green with envy; every 18 minutes and 18 seconds for three months, this veritable cosmic metronome emitted radio waves with a variability of less than one ten thousandth of a second.

The hunt for repeats

There are many celestial bodies capable of producing a periodic radio signal. When you cross their path, one of the first reflexes is often to think of a pulsar. The life cycle of these objects begins with the explosion of a massive star exploding; this leaves behind an extremely dense remains, composed almost exclusively of neutrons, and which rotates on itself at a prodigious speed. We then speak of a neutron star.

Many of them have an extremely strong magnetic field. They then emit a stream of radio waves that travel through space. From Earth, it is sometimes possible to pick up these radio waves intermittently, much like the pulsations of a beating heart – hence the term pulsar.

A signal “extreme” with a strange periodicity

It is therefore a first track which could make it possible to explain this curious signal, at least in part. Because there are still quite mysterious elements, starting with the amazing signal strength which surprised the researchers. “It’s crazy, really, really, really extreme”, insists astronomer Natasha Hurley-Walker three times in a press conference.

And this is not the only element that turned out to be out of the ordinary during these observations. In addition to its power, the very strange periodicity of the signal also challenged the researchers. Indeed, within the framework of a pulsar, each “flash” of radio waves generally ranges from a few milliseconds to a few seconds. Here, each event lasted about a minute. A pattern that does not correspond to any other known astronomical phenomenon.

It was completely unexpected. And even rather frightening for an astronomer, because there is nothing known in the sky that exhibits such behavior.”
Natasha Hurley-Walker – ICRAR

A new type of magnetar never seen before?

A set of observations that have led researchers to suggest that it could therefore be a magnetar. It is a sub-category of pulsars with an extremely intense magnetic field, which could explain the strength of the signal detected… but not periodicity. The researchers suggest that they could be dealing with a new type of celestial body: un ultra-long-period magnetar.

At present, these are still theoretical objects; their existence has been predicted in scientific reading, but they have never been observed before. Unfortunately, whether or not it is a magnetar of this kind, it will be necessary to be patient to have the end of the story. Because after three months of activity, the source of the signal has literally gone into radio silence. Astronomers are no longer able to capture the radio waves previously identified, and will therefore continue to observe in the same direction, hoping to find the signal.

If that ends up happening, they might be able to confirm the ultra-long-period magnetar hypothesis. This would be a great first that will certainly advance our understanding of the life cycle of stars. “With additional observations, we will be able to determine if this was a one-off, one-time event or from a whole new population that we have so far eluded.”, concludes Natasha Hurley-Walker.

The research paper is available here.

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