Software offers new way to listen for signals from the stars

Akshay Suresh, a doctorate candidate in astronomy at Cornell University, is leading the Breakthrough Listen Investigation for Periodic Spectral Signals (BLIPSS), a groundbreaking effort to find periodic signals coming from the Milky Way's center. The study looks for recurring patterns as a technique to look for extraterrestrial intelligence (SETI) in the area around our solar system.

In order to increase sensitivity to periodic sequences of tiny pulses, the researchers created software based on the Fast Folding Algorithm (FFA), a powerful search technique. Their research article, titled "A 4-8 GHz Galactic Center Search for Periodic Technosignatures," appeared in The Astronomical Journal on May 30.

Radar is one of the many uses for directed periodic transmissions that people use today. Pulsars, which are fast spinning neutron stars that sweep beams of radio energy over the Earth, are naturally occurring astronomical phenomena that produce periodic signals. Such signals would stand out from the background of non-periodic transmissions in interstellar space, yet they would use a lot less energy than a transmitter that is broadcasting continually.

According to Suresh, "BLIPSS is an example of state-of-the-art software as a science multiplier for SETI." The Fast Folding Algorithm (FFA) is used by our open-source software to crunch over 1.5 million time series for periodic signals in around 30 minutes, which is a first for SETI.

Breakthrough Listen, the SETI Institute, and Cornell worked together to create BLIPSS. By concentrating on the Milky Way's core area, which is recognized for its high concentration of stars and possibly hospitable exoplanets, the effort considerably increases the likelihood of discovering proof of extraterrestrial technology. A beacon placed in the Milky Way's core would make it possible for extraterrestrials to communicate with significant portions of the Galaxy.

On known pulsars, the researchers tested their technique, and they were successful in detecting periodic emission as predicted. The researchers next looked at a bigger dataset of scans of the Galactic Center made with the Breakthrough Listen instrument on the 100-meter Green Bank Telescope (GBT) in West Virginia. BLIPSS searched for repeated signals in a smaller frequency range, less than one-tenth the breadth of a typical FM radio station, as opposed to pulsars, which radiate throughout a broad range of radio frequencies.

According to co-author and Breakthrough Listen project scientist Steve Croft, "the combination of these relatively narrow bandwidths with periodic patterns could be indicative of deliberate technological activities of intelligent civilizations." "Breakthrough Listen captures enormous volumes of data, and Akshay's technique provides a new method to help us search that haystack for needles that could provide tantalizing evidence of advanced extraterrestrial life forms," says Akshay of his technique.

The search for continuous signals has been the main focus of radio SETI's work up until this point, according to co-author and astronomer at the SETI Institute Vishal Gajjar. "Our research highlights the astounding energy efficiency of a series of pulses as a form of interplanetary communication over extremely large distances. Notably, this research represents the first-ever thorough effort to carry out in-depth searches for these signals.

Provided by Cornell University