What appears in the sky, sends out radio signals at random, and then vanishes for months at a time? Since January of last year, a mysterious radio signal from near our galaxy’s core has puzzled astronomers.
A team of international astronomers published their findings in The Astrophysical Journal. According to them, the signal is so strange that it could be coming from a new type of celestial object.
The signal was first detected by the team while scanning the sky in outback Western Australia with the Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope.
The signal reappeared four times in a row in just a few weeks, according to study co-author Tara Murphy of the University of Sydney, who spoke to ABC News.
Also, the signal’s strength can change dramatically, becoming 100 times stronger in the radio spectrum. Even stranger, the radio waves are aligned in a single direction that rotates as the signal travels towards us.
What could it be?
1st possibility: A Pulsar
The first option considered was a pulsar, which is the rapidly spinning heart of a dead star. It periodically emits extremely fast pulses of energy, much like a clock.
The team turned to the Parkes Radio Telescope, which is well-known for its ability to detect pulsars. Unfortunately, they were unable to locate anything that could be the source.
Then, they went to the MeerKAT radio telescope in South Africa to find out more. After three months of silence, they detected a single signal that was almost as strong as the original before fading away. Although the signal had pulsar-like properties, there were no fast pulses.
Space telescopes also discovered no objects in the area emitting light in the X-ray and infrared ranges. It would have indicated that the source was a pulsar or a magnetar, another type of dead star, but found none.
2nd possibility: A massive flare from a star
The team then investigated if the signal could have been caused by a massive flare from a star. “This object was so bright that if it was a star, we should be able to see it in visible light. But… we didn’t see it at all; it was completely invisible,” Professor Murphy said.
3rd possibility: A Cosmic burper
The only other possibility is that it is one of the rare galactic center radio transients, dubbed the “cosmic burper.”
“It could be that we’ve discovered one of these, so in a way that’s exciting, because there are very few of them known. Also frustrating because we don’t actually know what galactic centre radio transients actually are,” Professor Murphy said.
The properties of cosmic burper are all slightly different from each other, but they are all different. We don’t know enough about them to say if they’re related or not.
New radio telescopes reveal more mysteries of the universe
Radio telescopes like ASKAP Pathfinder and MeerKAT have made it possible to see deeper into the vast universe. They are the first stages of the Square Kilometre Array’s (SKA). With the SKA, it may be possible to find even fainter transient objects.
Using the ASKAP telescope, Professor Murphy hopes to find more rare cosmic objects and understand them more.
“That’s how things often happen in astronomy. You find one rare thing, then you find more like it. Eventually, you can actually understand what’s going on,” she said.
