The Wow! Signal deciphered—it was hydrogen all along, study says

In 1977, astronomers obtained a strong, peculiar radio sign from the route of the constellation Sagittarius. Its frequency was the identical as impartial hydrogen, and astronomers had speculated that any ETIs making an attempt to speak would naturally use this frequency. Now the sign, named the Wow! Sign has change into lore within the SETI world.

However what was it?

Starting within the Seventies, the Ohio State College Huge 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, Huge Ear detected the peculiar sign that is taken on a lifetime of its personal. The Wow! Sign was a robust narrowband radio sign proper close to the frequency of impartial hydrogen. The Huge 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 through which Huge Ear was capable of observe it. A couple of days later, astronomer Jerry R. Ehman was trying over the info 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 identify has caught ever since.

The sign has one other identify: 6EQUJ5. This has been interpreted as a message hidden within the sign, however it actually represents how the sign’s depth assorted over time.

The sign generated plenty of 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 might be from an unexplained pure phenomenon.

New analysis exhibits that the Wow! Sign has a completely pure rationalization.

The research is titled “Arecibo Wow! I: An Astrophysical Rationalization for the Wow! Sign.” The lead creator is Abel Méndez from the Planetary Habitability Laboratory on the College of Puerto Rico at Arecibo. It is obtainable on the preprint server arXiv.

Arecibo Wow! is a brand new effort based mostly on an archival research of information from the now-defunct Arecibo Radio Telescope from 2017 to 2020. The observations from Arecibo are just like these from Huge Ear however “are extra delicate, have higher temporal resolution, and embody polarization measurements,” in response to the authors.

“Our newest observations, made between February and Might 2020, have revealed comparable narrowband alerts close to the hydrogen line, although much less intense than the unique Wow! Sign,” mentioned Méndez.

Arecibo detected alerts just like the Wow! sign however with some variations. They’re far much less intense and are available from a number of places. The authors say these alerts are simply defined by an astrophysical phenomenon and that the unique Wow! sign is just too.

“We hypothesize that the Wow! Sign was brought on by sudden brightening from stimulated emission of the hydrogen line as a result of a robust transient radiation supply, akin to a magnetar flare or a delicate gamma repeater (SGR),” the researchers write. These occasions are uncommon and depend on exact situations and alignments. They’ll trigger clouds of hydrogen to brighten significantly for seconds and even minutes.

The researchers say that what Huge Ear noticed in 1977 was the transient brightening of one in all a number of H1 (neutral hydrogen) clouds within the telescope’s line of sight. The 1977 sign was just like what Arecibo noticed in lots of respects. “The one distinction between the alerts noticed in Arecibo and the Wow! Sign is their brightness. It’s exactly the similarity between these spectra that means a mechanism for the origin of the mysterious sign,” the authors write.

These alerts 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 have been capable of establish the clouds answerable for the sign however not the supply. Their outcomes counsel 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 might be the primary recorded occasion of an astronomical maser flare within the hydrogen line,” the authors clarify of their conclusion.