In 1977, astronomers acquired a robust, peculiar radio sign from the course of the constellation Sagittarius. Its frequency was the identical as impartial hydrogen, and astronomers had speculated that any ETIs trying to speak would naturally use this frequency. Now the sign, named the Wow! Sign has develop into lore within the SETI world.
However what was it?
Starting within the Nineteen Seventies, the Ohio State College Massive Ear radio telescope was used within the college’s Seek for Extraterrestrial Intelligence (SETI) program, which ran from 1973 to 1995. This program is the longest-running SETI program in historical past.
In 1977, Massive Ear detected a peculiar sign that’s taken on a lifetime of its personal: the Wow! Sign. The Wow! Sign was a robust narrowband radio sign proper close to the frequency of impartial hydrogen. The Massive Ear telescope is lengthy gone now, however the effort to know what the sign is lives on.
The sign lasted the complete 72-second window wherein Massive Ear was capable of observe it. A number of days later, astronomer Jerry R. Ehman was trying over the information when he noticed the sign on a pc printout. Astronomers had by no means seen something prefer it, and he wrote “Wow!” beside it, and the title has caught ever since.
The sign has one other title: 6EQUJ5. This has been interpreted as a message hidden within the sign, but it surely actually represents how the sign’s depth diversified over time.
The sign generated numerous pleasure. Some thought it was extraterrestrial in origin, some thought it may come from some sort of human-generated interference, and a few thought it may very well be from an unexplained pure phenomenon.
New analysis exhibits that the Wow! Sign has a completely pure rationalization.
The analysis is “Arecibo Wow! I: An Astrophysical Explanation for the Wow! Signal.” The lead creator is Abel Méndez from the Planetary Habitability Laboratory on the College of Puerto Rico at Arecibo. It’s accessible on the pre-print server arxiv.org.
Arecibo Wow! is a brand new effort based mostly on an archival research of knowledge from the now-defunct Arecibo Radio Telescope from 2017 to 2020. The observations from Arecibo are much like these from Massive Ear however “are extra delicate, have higher temporal decision, and embrace polarization measurements,” in keeping with the authors.
“Our newest observations, made between February and Might 2020, have revealed related narrowband indicators close to the hydrogen line, although much less intense than the unique Wow! Sign,” mentioned Méndez.
Arecibo detected indicators much like the Wow! sign however with some variations. They’re far much less intense and are available from a number of areas. The authors say these indicators are simply defined by an astrophysical phenomenon and that the unique Wow! sign is, too.
“We hypothesize that the Wow! Sign was brought on by sudden brightening from stimulated emission of the hydrogen line because of a robust transient radiation supply, corresponding to a magnetar flare or a tender gamma repeater (SGR),” the researchers write. These occasions are uncommon and depend on exact circumstances and alignments. They will trigger clouds of hydrogen to brighten significantly for seconds and even minutes.
The researchers say that what Massive Ear noticed in 1977 was the transient brightening of one among a number of H1 (impartial hydrogen) clouds within the telescope’s line of sight. The 1977 sign was much like what Arecibo noticed in lots of respects. “The one distinction between the indicators noticed in Arecibo and the Wow! Sign is their brightness. It’s exactly the similarity between these spectra that implies a mechanism for the origin of the mysterious sign,” the authors write.
These indicators are uncommon as a result of the spatial alignment between supply, cloud, and observer is uncommon. The rarity of alignment explains why detections are so uncommon.
The researchers had been capable of determine the clouds answerable for the sign however not the supply. Their outcomes recommend that the supply is way more distant than the clouds that produce the hydrogen sign. “Given the detectability of the clouds as demonstrated in our information, this perception may allow exact location of the sign’s origin and allow steady monitoring for subsequent occasions,” the researchers clarify.
The Wow! Sign was initially interpreted as a technosignature by many. By explaining the place the sign got here from, this analysis outlines a brand new supply of false positives.
“Our speculation explains all noticed properties of the Wow! Sign, proposes a brand new supply of false positives in technosignature searches, and means that the Wow! Sign may very well be the primary recorded occasion of an astronomical maser flare within the hydrogen line,” the authors clarify of their conclusion.
