This suggests these signals come from human technology, although the scientists were unable to identify their precise source. Specifically, when it comes to BLC1 and its roughly 60 brethren, 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, Sheikh explained. "The fact that it took us a number of months to conduct all the analysis necessary to allow us to draw a conclusion is evidence of the challenge this signal presented." The scientists think BLC1 "is most likely an extreme example of local interference, in the sense that its properties are very different from other interference and it thus could mimic a bonafide technosignature," Siemion said. This suggests BLC1 is similarly not a genuine technosignature. However, when Sofia Sheikh, a radio astronomer at the University of California, Berkeley, and co-author on both new studies, dug into a larger dataset of observations taken at other times, she found about 60 signals that share many features of BLC1 but are also seen in their respective "off" observations. The scientists detailed their findings in two studies online Oct. ![]() "BLC1 represents the best candidate signal we have had in the Listen program since beginning the program in 2015," Siemion said. The remaining signal of interest, dubbed BLC1, persisted for more than two hours of observations and appeared to be present only in "on" observations from Proxima Centauri. ![]() "Searching for technosignatures is a rigorous and deliberative scientific endeavor that demands attention to detail and a high degree of skepticism," astrophysicist Andrew Siemion at the University of California, Berkeley, the principal investigator of Breakthrough Listen, told. For example, sometimes a faint signal was actually visible in the "off" observations but was not quite strong enough for the automated data analysis software to detect.Īrtist's concept of a violent flare erupting from the star Proxima Centauri. A candidate technosignature should appear only in the "on" observation, when the telescope was looking toward the star, whereas local sources are expected to have both "on" and "off" observations.Īfter scientists applied both these filters, they next visually inspected the remaining 5,160 candidates to weed out common mistakes. To determine this, the telescope pointed in the direction of the star and then pointed away, repeating this "on-off" pattern several times. ![]() Second, the researchers determined whether the remaining hits appeared to come from the direction of Proxima Centauri. Rejecting hits with no such hints of motion reduced the number of hits from about 4.1 million to about 1 million. A transmitter on a distant planet is expected to move with respect to whatever telescope on Earth detects it, leading to a Doppler shift in frequency (akin to how ambulance sirens sound higher-pitched as the vehicle drives toward you and lower-pitched as it moves away). Specifically, the researchers looked for radio signals that may have come from Proxima Centauri based on two main criteria.įirst, they looked at whether the signal was changing steadily in frequency over time. ![]() However, upon subsequent analysis, the vast majority of such hits usually turned out to be emissions from human technology here at Earth. Using the Parkes Telescope in Australia, one of the largest telescopes in the Southern Hemisphere, since 2016 the scientists have detected more than 4.1 million "hits," or frequency ranges that had signs of potentially significant radio signals.
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