The Wow! Signal Deciphered. It Was Hydrogen All Along.

The Wow! signal, detected on August 15, 1977, was an intense radio transmission that appeared artificial and raised the possibility of extraterrestrial contact. However, recent research suggests it may have been caused by a natural astrophysical event involving a magnetar flare striking a hydrogen cloud. Universe Today reports: New research shows that the Wow! Signal has an entirely natural explanation. The research is 'Arecibo Wow! I: An Astrophysical Explanation for the Wow! Signal.' The lead author is Abel Mendez from the Planetary Habitability Laboratory at the University of Puerto Rico at Arecibo. It's available at the pre-print server arxiv.org. Arecibo Wow! is a new effort based on an archival study of data from the now-defunct Arecibo Radio Telescope from 2017 to 2020. The observations from Arecibo are similar to those from Big Ear but 'are more sensitive, have better temporal resolution, and include polarization measurements,' according to the authors. 'Our latest observations, made between February and May 2020, have revealed similar narrowband signals near the hydrogen line, though less intense than the original Wow! Signal,' said Mendez.

Arecibo detected signals similar to the Wow! signal but with some differences. They're far less intense and come from multiple locations. The authors say these signals are easily explained by an astrophysical phenomenon and that the original Wow! signal is, too. 'We hypothesize that the Wow! Signal was caused by sudden brightening from stimulated emission of the hydrogen line due to a strong transient radiation source, such as a magnetar flare or a soft gamma repeater (SGR),' the researchers write. Those events are rare and rely on precise conditions and alignments. They can cause clouds of hydrogen to brighten considerably for seconds or even minutes.

The researchers say that what Big Ear saw in 1977 was the transient brightening of one of several H1 (neutral hydrogen) clouds in the telescope's line of sight. The 1977 signal was similar to what Arecibo saw in many respects. 'The only difference between the signals observed in Arecibo and the Wow! Signal is their brightness. It is precisely the similarity between these spectra that suggests a mechanism for the origin of the mysterious signal,' the authors write. These signals are rare because the spatial alignment between source, cloud, and observer is rare. The rarity of alignment explains why detections are so rare. The researchers were able to identify the clouds responsible for the signal but not the source. Their results suggest that the source is much more distant than the clouds that produce the hydrogen signal. 'Given the detectability of the clouds as demonstrated in our data, this insight could enable precise location of the signal's origin and permit continuous monitoring for subsequent events,' the researchers explain.

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