Jun 03, 2022 I Paul Seaburn

Astronomers Discover a Mysterious Radio Signal They Can't Explain

The search for extraterrestrial intelligence requires a lot of patient listening by astronomers around the world for signals that may or may not be recognizable. Some, like fast radio bursts, are puzzling and alien-like at first but move closer to identification as each new one is detected. Others, like the famous WOW! signal, defy resolutions decades after their detection. Australian astronomers watching a spiral galaxy picked up a mysterious compact radio source which has so far eluded classification. Will it be the first alien signal? Does it deserve a ‘wow’ or a ‘wtf’?

Australian astronomers led by Joel Balzan at Western Sydney University reveal in a new arXiv preprint paper (it will be published in the journal Astrophysics and Space Science) their recent strange discovery in the spiral galaxy NGC 2082 is an intermediate spiral galaxy in the Dorado constellation in the southern sky for the dolphinfish (Coryphaena hippurus), which is known as ‘dorado’ in Spanish. Using the Australian Square Kilometer Array Pathfinder (ASKAP), the Parkes Observatory radio telescope and the Australian Telescope Compact Array (ATCA), Balzan and his team were scanning NGC 2082 primarily because no one had paid much attention to it before. That was a gratuitous decision as the spiral galaxy 60 million light years from Earth sent them a wave.

NGC 2082

“We present radio continuum observations of NGC 2082 using ASKAP, ATCA and Parkes telescopes from 888 MHz to 9000 MHz. Some 20 arcsec from the centre of this nearby spiral galaxy, we discovered a bright and compact radio source, J054149.24-641813.7, of unknown origin.”

J054149.24-641813.7 is a ‘radio source’ – these are objects in the universe that emit relatively large amounts of radio waves and are generally identified as pulsars, certain nebulas, quasars, and radio galaxies. J054149.24-641813.7 was bright and compact, so the team was able to rule out the above list as its source. J054149.24–641813.7 is located in an outer part of the NGC 2082, which is often where fast radio bursts (FRBs) come from. However, the researchers decided that this particular radio source wasn’t strong enough to be a one-time or repeating source of fast radio bursts.

“We see this ONLY in radio frequencies.”

Western Sydney University professor Miroslav Filipovic, who can take credit for assigning Balzan to the task of scanning NGC 2082, told IFLScience that if the radio source isn’t in the spiral galaxy, then it’s someplace else. Because J054149.24–641813.7 was so powerful relative to its surroundings, Filipovic thought the radio source might be in front of NGC 2082, possibly even in our own Milky Way galaxy. Unfortunately, this type of signal is only seen in radio frequencies, not stars or supernovas or hypernovas, so he ruled out the source being out front. The other possibility is that J054149.24–641813.7 is so strong, its signal blasted out from BEHIND NGC 2082.

“We find that the probability of finding such a source behind NGC 2082 is P = 1.2%, and conclude that the most likely origin for J054149.24-641813.7 is a background quasar or radio galaxy.”

A radio galaxy has giant regions of radio emission blasting out from its active galactic center and extending far beyond its visible structure. These are almost always elliptical rather than spiral galaxies and typically contain the most massive of supermassive black holes, so their signals can easily blast through weaker areas of other galaxies. That sounds like a winner … except the team only put the probability at 1.2 percent – not even close enough for government work. What Balzan and the team say they need is high resolution neutral atomic hydrogen (HI) absorption data for NGC 2082 which would prove it was absorbing most of the strong radio waves from a source behind it.

Elliptical galaxy ESO 325-G004

Or … they could say it’s aliens and enjoy their 15 minutes of fame.

Either way, this shows just how difficult the process of elimination is in the search for extraterrestrial intelligence.

Paul Seaburn

Paul Seaburn is the editor at Mysterious Universe and its most prolific writer. He’s written for TV shows such as "The Tonight Show", "Politically Incorrect" and an award-winning children’s program. He's been published in “The New York Times" and "Huffington Post” and has co-authored numerous collections of trivia, puzzles and humor. His “What in the World!” podcast is a fun look at the latest weird and paranormal news, strange sports stories and odd trivia. Paul likes to add a bit of humor to each MU post he crafts. After all, the mysterious doesn't always have to be serious.

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