The Breakthrough Listen Investigation for Periodic Spectral Signals (BLIPSS) is a novel software architecture utilizing a fast folding algorithm to enable routine searches for periodic technosignatures in radio data.
Radio SETI has focused on the discovery of narrowband signals and artificially dispersed broadband pulses from extraterrestrial worlds; in contrast to these technosignature morphologies, periodic spectral signals offer an energetically efficient means of transmission across vast interstellar distances; a rotating beacon at the Milky Way’s center is, in particular, advantageously placed for galaxy-wide communications. Image credit: Breakthrough Listen / Danielle Futselaar.
“The Search for Extraterrestrial Intelligence (SETI) is an active quest to find evidence of advanced alien life in the Universe through signatures of their technologies,” said Cornell University graduate student Akshay Suresh and colleagues.
“Radio SETI has been ongoing since the early 1960s.”
“Two broad categories of potential radio extraterrestrial intelligence signals are intentional beacon emissions and leakage radiation emanating from alien technologies.”
“Of these two technosignatures, the spectrotemporal characteristics of the latter are much harder to speculate. In addition, such leakage signals are likely to be weaker.”
“Hence, modern radio SETI efforts have primarily focused on wideband searches for deliberate narrowband beacons from Galactic planetary systems and neighboring galaxies.”
By directing their focus towards the central region of the Milky Way, with its dense congregation of stars and possibly habitable exoplanets, the BLIPSS astronomers amplify the odds of capturing compelling evidence of extraterrestrial technology.
If an alien civilization wanted to communicate with other civilizations throughout the Milky Way, the Galaxy’s core holds potential as a strategic site for a beacon.
“Of all directions in the sky, the line of sight toward the Galactic center offers the greatest propensity for the emergence of intelligent life,” they explained.
“Further, radial beacons from the Galactic center are viable given their advantageous positioning for galaxy-wide communications.”
“Thus, the Galactic center is an ideal first target for our periodic technosignature searches.”
The team began by testing their BLIPSS algorithm on known pulsars, successfully detecting the expected periodic emissions.
Subsequently, they turned their attention to a dataset of scans of the Galactic center captured by the Breakthrough Listen instrument on the Green Bank Telescope (GBT) in West Virginia.
Unlike pulsars, which emit signals across a broad range of radio frequencies, BLIPSS narrowed its search to repeating signals within a narrower frequency range — covering less than a tenth of the width of an average FM radio station.
“The combination of these relatively narrow bandwidths with periodic patterns could be indicative of deliberate technological activities of intelligent civilizations,” said Dr. Steve Croft, the Breakthrough Listen project scientist for GBT and adjunct senior astronomer at the SETI Institute.
“Breakthrough Listen captures huge volumes of data, and the BLIPSS technique provides a new method to help us search that haystack for needles that could provide tantalizing evidence of advanced extraterrestrial life forms.”
“Until now, radio SETI has primarily dedicated its efforts to the search for continuous signals,” said Dr. Vishal Gajjar, an astronomer at the SETI Institute.
“Our study sheds light on the remarkable energy efficiency of a train of pulses as a means of interstellar communication across vast distances.”
“Notably, this study marks the first-ever comprehensive endeavor to conduct in-depth searches for these signals.”
The team’s work is published in the Astronomical Journal.
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Akshay Suresh et al. 2023. A 4-8 GHz Galactic Center Search for Periodic Technosignatures. AJ 165, 255; doi: 10.3847/1538-3881/acccf0
