Final yr, astronomers made an intriguing discovery: a radio sign in house that switched on and off each 18 minutes.

Astronomers count on to see some repeating radio indicators in house, however they normally blink on and off rather more rapidly. The commonest repeating indicators come from pulsars, rotating neutron stars that emit energetic beams like lighthouses, inflicting them to blink on and off as they rotate in the direction of and away from the Earth.

Pulsars decelerate as they become older, and their pulses develop into fainter, till ultimately they cease producing radio waves altogether. Our unusually gradual pulsar may finest be defined as a magnetar—a pulsar with exceedingly complicated and highly effective magnetic fields that would generate radio waves for a number of months earlier than stopping.

Sadly, we detected the supply utilizing information gathered in 2018. By the point we analysed the information and found what we thought could be a magnetar it was 2020, and it was not producing radio waves. With out further information, we had been unable to check our magnetar concept.

Nothing New Beneath the Solar

Our Universe is huge, and to date each new phenomenon we’ve found has not been distinctive. We knew that if we regarded once more, with well-designed observations, we had a very good probability of discovering one other long-period radio supply.

So, we used the Murchison Widefield Array radio telescope in Western Australia to scan our Milky Approach galaxy each three nights for a number of months.

We didn’t want to attend lengthy. Nearly as quickly as we began trying, we discovered a brand new supply, in a unique a part of the sky, this time repeating each 22 minutes.

Eventually, the second we had been ready for. We used each telescope we may discover, throughout radio, X-ray, and optical mild, making as many observations as doable, assuming it could not be lively for lengthy. The pulses lasted 5 minutes every, with gaps of 17 minutes between. Our object regarded lots like a pulsar, however spinning 1,000 instances slower.

Hiding in Plain Sight

The actual shock got here after we searched the oldest radio observations of this a part of the sky. The Very Giant Array in New Mexico, United States, has the longest-running archive of knowledge. We discovered pulses from the supply in information from yearly we regarded—the oldest one in an statement made in 1988.

Observing over three a long time meant we may exactly time the pulses. The supply is producing them like clockwork, each 1,318.1957 seconds, give or take a tenth of a millisecond.

In keeping with our present theories, for the supply to be producing radio waves, it must be slowing down. However based on the observations, it isn’t.

In our article in Nature, we present that the supply lies “beneath the loss of life line,” which is the theoretical restrict of how neutron stars generate radio waves; this holds even for fairly complicated magnetic area fashions. Not solely that, but when the supply is a magnetar, the radio emission ought to solely be seen for a couple of months to years—not 33 years and counting.

So after we tried to unravel one downside, we by chance created one other. What are these mysterious repeating radio sources?

What About ET?

In fact, it’s very tempting at this level to succeed in to extraterrestrial intelligence as an possibility. The identical factor occurred when pulsars had been found: astrophysicist Jocelyn Bell Burnell and her colleagues, who discovered the primary pulsar, nicknamed it “LGM 1,” for “Little Inexperienced Males 1.”

However as quickly as Bell and her colleagues made additional detections, they knew it couldn’t be aliens. It could be extremely unlikely for therefore many comparable indicators to be coming from so many various elements of the sky.

The pulses, much like these of our supply, contained no info, simply “noise” throughout all frequencies, similar to pure radio sources. Additionally, the power necessities to emit a sign in any respect frequencies are staggering: you could use, nicely, a neutron star.

Whereas it’s tempting to attempt to clarify a brand new phenomenon this manner, it’s a little bit of a cop out. It doesn’t encourage us to maintain considering, observing, and testing new concepts. I name it the “aliens of the gaps” method.

Luckily, this supply continues to be lively, so anybody on the earth can observe it. Maybe with artistic follow-up observations, and extra evaluation, we’ll have the ability to resolve this new cosmic thriller.

This text is republished from The Dialog beneath a Inventive Commons license. Learn the unique article.

Picture Credit score: The Worldwide Centre for Radio Astronomy Analysis