What once appeared to be a possible signal from Proxima Centauri was probably just an echo from Earth. Astronomers dedicated to searching space for signs of technology created by extraterrestrial intelligence, also known as technosignatures, say one promising lead now looks to have been a false positive.
"Evidence suggests that the signal is interference from human technology, although we were unable to identify its specific source," explains Sofia Sheikh with the Breakthrough Listen team, in a statement.
The Breakthrough Listen initiative helps support the search for extraterrestrial intelligence, and in 2020 team members using the Parkes telescope in Australia reported an intriguing signal picked up when they pointed the telescope at Proxima Centauri, the nearest known star beyond our solar system.
But after Sheikh performed a deeper analysis of the signal, it began to look much less alien, explains Andrew Siemion at the University of California, Berkeley, who also leads Listen's science team.
"In the case of this particular candidate," Siemion says, "our analysis suggests it's highly unlikely that it is really from a transmitter out at Proxima Centauri. However, this is undoubtedly one of the most intriguing signals we've seen to date."
Sheikh added that "the signals are spaced at regular frequency intervals in the data, and these intervals appear to correspond to multiples of frequencies used by oscillators that are commonly used in various electronic devices."
The analysis is laid out in two new papers published Monday in Nature Astronomy.
So once again, after decades of searching the cosmos, the result is still "it's not aliens." But Breakthrough Initiatives Executive Director Pete Worden says the latest report helps to further fine-tune the process of filtering out false positives.
"While we were unable to conclude a genuine technosignature, we are increasingly confident that we have the necessary tools to detect and validate such signatures if they exist."