The search for extraterrestrial civilizations gains an important new tool

The VERITAS array is a collection of four 12-meter Cherenkov telescopes used to detect astrophysical sources of very-high-energy gamma rays. (Photo credit: Steve Criswell, SAO)

SCIPP physicist David Williams will help lead effort using four 12-meter telescopes to search for nanosecond flashes of light from extraterrestrial civilizations

The Breakthrough Listen initiative to find signs of intelligent life in the universe will collaborate with the VERITAS Collaboration in the search for technosignatures, signs of technology developed by intelligent life beyond the Earth.

Joining the Breakthrough Listen initiative’s ongoing radio frequency survey and spectroscopic optical laser survey, VERITAS (the Very Energetic Radiation Imaging Telescope Array System) will search for pulsed optical beacons with its array of four 12-meter telescopes at the Fred Lawrence Whipple Observatory in Amado, Arizona.

VERITAS is the world’s most powerful telescope array for studying high-energy astrophysics with gamma rays. It detects gamma rays coming from space by looking for the extremely brief flashes of blue “Cherenkov” light they create when they hit the top of the Earth’s atmosphere.

VERITAS will look for pulsed optical beacons with durations as short as several nanoseconds. Over such timescales, artificial beacons could easily outshine any stars that lie in the same direction on the sky. The use of all four telescopes simultaneously allows for very effective discrimination against false positive detections. The VERITAS Collaboration has previously published observations of the mysteriously dimming Boyajian’s Star in search of such optical pulses. The new program of VERITAS observations will provide complementary searches for optical pulse signatures of many more stars from the primary Breakthrough Listen star list.

“It is impressive how well-suited the VERITAS telescopes are for this project, since they were built only with the purpose of studying very-high-energy gamma rays in mind,” said David Williams, adjunct professor of physics at UC Santa Cruz and the Santa Cruz Institute for Particle Physics (SCIPP) and a member of the VERITAS collaboration.

Breakthrough Listen’s search for optical technosignatures with VERITAS will be led by Williams at UCSC and Jamie Holder of the University of Delaware, in collaboration with the Listen team at UC Berkeley’s SETI Research Center led by Andrew Siemion.

“When it comes to intelligent life beyond Earth, we don’t know where it exists or how it communicates,” said Yuri Milner, founder of the Breakthrough Initiatives. “So our philosophy is to look in as many places, and in as many ways, as we can. VERITAS expands our range of observation even further.”

“Breakthrough Listen is already the most powerful, comprehensive, and intensive search yet undertaken for signs of intelligent life beyond Earth,” Siemion said. “Now, with the addition of VERITAS, we’re sensitive to an important new class of signals: fast optical pulses. Optical communication has already been used by NASA to transmit high definition images to Earth from the moon, so there’s reason to believe that an advanced civilization might use a scaled-up version of this technology for interstellar communication.”

If a laser comparable to the most powerful lasers on Earth (delivering about 500 terawatts in a pulse lasting a few nanoseconds) were situated at the distance of Boyajian’s Star and pointed in our direction, VERITAS could detect it. But most of the stars in the Listen target list are 10 to 100 times closer than Boyajian’s Star, meaning that the new search will be sensitive to pulses a factor 100 to 10,000 times fainter still.

“Using the huge mirror area of the four VERITAS telescopes will allow us to search for these extremely faint optical flashes in the night sky, which could correspond to signals from an extraterrestrial civilization,” said Holder.

Learn more: Breakthrough Listen launches new optical search with VERITAS Telescope Array