On Wednesday, July 19 the researchers reported the discovery of a new astronomical mystery. The object, designated GPM J1839-10, behaves a bit like a pulsar – a rotating neutron star that periodically emits bursts of radio energy. However, almost every pulsar we know “blinks” at least once a minute, while the flashes from GPM J1839-10 come every 22 minutes.
GPM J1839-10 was discovered during a search for transient objects in the galactic plane. Transitional objects are objects or phenomena that manifest themselves only for a short time or in a limited period of time. They are not permanently visible, but can only be observed during a certain period, which can last from a few seconds to several days, months or even years.
A typical example are supernovae, in which, due to the explosion, there is a huge increase in the brightness of previously invisible stars.
Mysterious radio signal
As pulsars age, they slow down and their pulses weaken until they eventually stop emitting radio waves altogether. The unusually slow pulsar could best be explained as a magnetar – a pulsar with an extremely complex and strong magnetic field that can generate radio waves for several months before it “goes out”.
“We detected the source using data obtained in 2018. By the time we analyzed the data and discovered what we thought might be a magnetar, it was 2020 and the source no longer produced any radio waves. Without more data, we could not verify our magnetar theory.” writes astronomer Natasha Hurley-Walker in an article for The Conversation.
Therefore, scientists used the Murchison Widefield Array radio telescope in Western Australia, with which they scanned our Milky Way galaxy for several months. They didn’t have to wait long – almost as soon as they started looking, they found a new source in another part of the sky, the flashes of which were repeated every 22 minutes. The pulses lasted for five minutes with breaks every 17 minutes. The object looked similar to a pulsar, but rotated a thousand times slower.
A big scientific surprise
The real surprise came when astronomers searched through older radio observations of this part of the sky. The Very Large Array in New Mexico in the United States has the longest data archive. Impulses from the source were traced back in data from each year – the oldest of these was from the 1988 observation.
With more than three decades of observation, it was possible to accurately calculate the time between pulses. It turns out that the source produces them every 1,318.1957 seconds, plus or minus one-tenth of a millisecond. According to current scientific theories, the source that produces the radio waves should slow down. However, according to observations, this is not the case.
In the article, published in the scientific journal Nature, the researchers showed that the source lies “below the death line,” the theoretical limit of when neutron stars generate radio waves. This also applies to relatively complex magnetic field models. If the source is a magnetar, the radio emissions should only be observable for a few months to years – not 33 years or older.
Would aliens?
“So when we tried to solve one problem, we inadvertently created another. What are these mysterious repeating radio sources?’ asks Hurley-Walker. Of course, at such a moment it is very tempting to reach for an extraterrestrial civilization as an option.
The same thing happened with the discovery of pulsars: astrophysicist Jocelyn Bell Burnell and her colleagues, who discovered the first pulsar, gave it the nickname “LGM 1”, i.e. “Little Green Men 1”.
However, as Bell and her team made further detections, they realized that they cannot be aliens. It would be incredibly unlikely that so many similar signals would come from so many different parts of the sky. The pulses, similar to those from the mysterious source, contained no information, just “noise” at all frequencies, just like natural radio sources. Also, the energy requirements for transmitting a signal to such a distance on all frequencies would be staggering.
“It’s tempting to try to explain a new phenomenon in this way, but it’s a bit of an excuse. It doesn’t encourage us to keep thinking, observing and testing new ideas.” notes Hurley-Walker. Fortunately, this source is still active, so it can be observed by scientists around the world. Perhaps it is thanks to further observations and analyzes that this new cosmic mystery will be solved.
2023-07-20 14:46:26
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