A new search for extraterrestrial life aims to find out by listening for radio pulses from the center of our galaxy. Narrow-frequency pulses are naturally emitted by stars called pulsars, but they're also used deliberately by humans in technology such as radar.
Because these pulses stand out against the background radio noise of space, they're an effective way of communicating across long distances — and an appealing target to listen for when searching for alien civilizations.
Scientists described the alien-hunting strategy in a new study, published in The Astronomical Journal. Researchers led by Cornell University graduate student Akshay Suresh developed software to detect these repetitive frequency patterns and tested it on known pulsars to be sure it could pick up the narrow frequencies.
These frequency ranges are very small, at about a tenth of the width of frequencies used by a typical FM radio station. The researchers then searched data from the Green Bank Telescope in West Virginia using the method.
"Until now, radio SETI has primarily dedicated its efforts to the search for continuous signals," study coauthor Vishal Gajjar of the SETI Institute, a nonprofit organization dedicated to the search for intelligent life in the universe, said in a statement. "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 researchers are listening in to the middle of the Milky Way because it is dense with stars and potentially habitable exoplanets. What's more, if intelligent aliens at the core of the Milky Way wanted to reach out to the rest of the galaxy, they could send signals sweeping across a wide array of planets, given their privileged position at the center of the galaxy.
Using narrow bandwidths and repeated patterns would be a prime way for aliens to reveal themselves, as such a combination is extremely unlikely to occur naturally, study co-author Steve Croft, a project scientist with the Breakthrough Listen program, said in a separate statement.
The method uses an algorithm that can search through 1.5 million telescope data samples in 30 minutes. Though researchers did not find any telltale signs in their first search, they say that the speed of the algorithm will help improve searches in the future.
"Breakthrough Listen captures huge 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," Croft said.
