In 2015, Russian-Israeli billionaire Yuri Milner and his nonprofit Breakthrough Initiatives launched the largest SETI project (The Search for Extraterrestrial Intelligence). Known as Groundbreaking Listening, this SETI effort relies on the world’s most powerful radio telescopes and advanced analytics to search for potential evidence of technological activity (called “technosignatures”). The ten-year project will explore the one million stars closest to Earth, the center of our galaxy, the entire galactic plane and the 100 closest galaxies to the Milky Way.

In 2018, they collaborated with the Very Energetic Radiation Imaging Telescope Array System (VERITAS), a ground-based gamma-ray telescope system operating at the Fred Lawrence Whipple Observatory (FLWO) atop Mount Hopkins in southern Arizona. In a recent article, the VERITAS Collaboration shared the results of the first year of search for “optical techno-signatures” (2019 – 2020). Their results are an important proof-of-concept showing how future searches for extraterrestrial civilizations could incorporate optical pulses into techno-signature catalogs.

The VERITAS collaboration is an international initiative that includes researchers from FLWO, Harvard-Smithsonian Center for Astrophysics (CfA), Canadian Arthur B. Macdonald Research Institute for Particle Astrophysics, Deutsches Electronen-Synchrotron (DESY), NASA Goddard Center. space flights as well as numerous universities and research institutes. A preprint of their article titled “A VERITAS/Breakthrough Listen Search for Optical Technosignatures” has recently been published online.

In the six decades since Project Ozma, the search for ETI has focused almost entirely on finding evidence of radio broadcasts. In recent years, scientists have expanded research to consider other potential techno-signatures such as directed energy communications, radio and optical leakage from technological civilizations, infrared radiation from megastructures, spectral evidence of industrial pollutants in exoplanet atmospheres, and even spacecraft or debris. in our solar system.

These, and other potential examples of extraterrestrial technology, were described in a NASA Technosignature Workshop report published in 2018. The inclusion of the VERITAS array, consisting of four 12-metre (~40 ft) optical Cherenkov reflectors for gamma-ray astronomy, allowed Breakthrough Listen to expand its search for optical techno-signatures – particularly nanosecond optical pulses detectable at interstellar distances. Gregory Foote, PhD Candidate, Department of Physics and Astronomy
The University of Delaware (UD) and co-author of the VERITAS article explained via email to Universe Today:

“While traditionally radio signatures have been searched for, we don’t know what waveband the signal will come from, whether it will be pulsed or continuous, so it makes sense to search in as many different ways as possible. The techno-signature we’re looking for is a pulsed laser (in principle) easily detected with current technology. “The VERITAS system itself allows us to search for these pulsed lasers with some of the largest telescopes on the planet.”

Completed in 2007, the VERITAS array effectively complements NASA’s Space Gamma-ray Telescope. Fermi (FRGST) and the collaborative Wide Field Telescope (LAT) with which Fermi is a partner due to its larger collection area and higher gamma-ray sensitivity. In fact, VERITAS segmented reflector telescopes are similar to main mirrors. James Webb Space Telescope (JWST) – Highest sensitivity of any telescope in the Very High Energy (VHE) range, with a maximum sensitivity of 100 Giga. -electronvolts (GeV) to 10 teraelectronvolts (TeV).

These possibilities were put to the test when the Collaboration team searched the Breakthrough Listening targets catalog for signs of high-energy optical pulses. foot said:

“We started with the Breakthrough Listen target catalog released in 2017, and then we removed anything that didn’t work for VERITAS. That left us about 506 possible targets, which were then sorted by proximity, eclipse, and other nice things like the presence of exoplanets. This ranking list gave us a good tool to choose which ones to watch because we chose the highest rankings that can be seen in a given month. We made a total of 30 hours of observations, each observation took about 15 minutes. In the end, we observed 136 targets because there were several observations involving multiple objects.”

In addition, the Collaboration team reviewed the archive VERITAS data for 2012. The team then calculated which targets in the Breakthrough Listen catalog were observed by VERITAS over the same period. Because of their limited computation time, they decided to extend archive analysis to many different purposes by analyzing only the first hour of qualitative data. “This leaves us with 249 observations of 119 non-overlapping fields containing 140 randomly captured targets,” Foote said. “Unfortunately, we found no evidence of this techno signature of these targets in any of the observations we analyzed.”

While their analysis did not show any evidence of nanosecond optical pulses, the study provided an important proof-of-concept that will inform future searches. It also helped narrow those searches and increase the likelihood of future exploration by placing a limit on the number of stars that could host donor civilizations. Additionally, Foote said this research could have important implications for existing and planned gamma-ray observatories. This includes the Panoramic Near Infrared and All-Time Optical Techno-signals Seeker (PANOSETI), which will conduct coordinated observations with the Veritas Observatory:

“I think the biggest impact on the wider field is that this techno-signature can be searched for by linking existing gamma-ray observatories, including VERITAS, with those that are yet to be built. Observatories built specifically for this techno-signature, like PANOSETI, have some gamma-ray observatories from it. “It also goes the other way, since it can get the science out. It’s a unique intersection of hitherto unstudied deposits.” Source