Breakthrough Listen Scans Milky Way Galaxy for Beacons of Civilization

Artist’s concept of a nearby civilization signaling Earth after observing our planet crossing in front of the sun. Astronomers have now scanned 20 nearby stars in the Earth transit zone in search of such signals. (Image: UC Berkeley courtesy of Breakthrough Listen)
Artist’s concept of a nearby civilization signaling Earth after observing our planet crossing in front of the sun. Astronomers have now scanned 20 nearby stars in the Earth transit zone in search of such signals. (Image: UC Berkeley courtesy of Breakthrough Listen)

The Breakthrough Listen Initiative released data from the most comprehensive survey yet of radio emissions from the plane of the Milky Way Galaxy and the region around its central black hole, and it is inviting the public to search the data for signals from intelligent civilizations.

At a media briefing in Seattle as part of the annual meeting of the American Association for the Advancement of Science (AAAS), Breakthrough Listen’s principal investigator Andrew Siemion of the University of California, Berkeley, announced the release of nearly 2 petabytes of data, the second data dump from the 4-year-old search for extraterrestrial intelligence (SETI). A petabyte of radio and optical telescope data was released last June, the largest release of SETI data in the history of the field.

The data, most of it fresh from the telescope prior to detailed study from astronomers, comes from a survey of the radio spectrum between 1 and 12 gigahertz (GHz). About half of the data comes via the Parkes radio telescope in New South Wales, Australia, which, because of its location in the Southern Hemisphere, is perfectly situated and instrumented to scan the entire galactic disk and galactic center. The telescope is part of the Australia Telescope National Facility, owned and managed by the country’s national science agency, CSIRO.

The remainder of the data was recorded by the Green Bank Observatory in West Virginia, the world’s largest steerable radio dish, and an optical telescope called the Automated Planet Finder, built and operated by UC Berkeley and located at Lick Observatory outside San Jose, California. Breakthrough Listen’s lead system administrator, Matt Lebofsky, said:

Yuri Milner, the founder of Breakthrough Listen, added:

The National Radio Astronomy Observatory (NRAO) and the privately-funded SETI Institute in Mountain View, California, also announced today an agreement to collaborate on new systems to add SETI capabilities to radio telescopes operated by NRAO.

The first project will develop a system to piggyback on the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) in New Mexico and provide data to state-of-the-art digital backend equipment built by the SETI Institute.

Moonset, around 2:30 a.m., at the Very Large Array on the Plains of San Agustin, about 50 miles west of Socorro, New Mexico. The VLA is teaming up with the SETI Institute to capture data that can be searched for intelligent signals.

Moonset, around 2:30 a.m., at the Very Large Array on the Plains of San Agustin, about 50 miles west of Socorro, New Mexico. The VLA is teaming up with the SETI Institute to capture data that can be searched for intelligent signals. (Image: J. Hellerman; NRAO / AU I/ NSF)

 

Siemion, who, in addition to his UC Berkeley position, is the Bernard M. Oliver Chair for SETI at the SETI Institute, said:

NRAO Director Tony Beasley, said:

Earth Transit Zone Survey

In releasing the new radio and optical data, Siemion highlighted a new analysis of a small subset of the data: radio emissions from 20 nearby stars that are aligned with the plane of Earth’s orbit such that an advanced civilization around those stars could see Earth pass in front of the Sun (a “transit” like those focused on by NASA’s Kepler space telescope). Conducted by the Green Bank Telescope, the Earth transit zone survey observed in the radio frequency range between 4 and 8 gigahertz, the so-called C-band.

The data were then analyzed by former UC Berkeley undergraduate Sofia Sheikh, now a graduate student at Pennsylvania State University, who looked for bright emissions at a single radio wavelength or a narrow band around a single wavelength. She has submitted the paper to the Astrophysical Journal.

Australia’s Parkes radio telescope, 210 feet in diameter, conducted the most comprehensive survey yet of radio emissions from the Milky Way galaxy in search of technosignatures from advanced civilizations around other stars. (Photo courtesy of CSIRO)

Australia’s Parkes radio telescope, 210 feet in diameter, conducted the most comprehensive survey yet of radio emissions from the Milky Way galaxy in search of technosignatures from advanced civilizations around other stars. (Image: courtesy of CSIRO)

Sheikh said:

While Sheikh and her team found no technosignatures of civilization, the analysis and other detailed studies the Breakthrough Listen group has conducted are gradually putting limits on the location and capabilities of advanced civilizations that may exist in our galaxy. Siemion said:

Sheikh noted that her mentor, Jason Wright at Penn State, estimated that if the world’s oceans represented every place and wavelength we could search for intelligent signals, we have, to date, explored only a hot tub’s worth of it. Sheikh said:

Beacons in the galactic center?

The so-far unanalyzed observations from the galactic disk and galactic center survey were a priority for Breakthrough Listen because of the higher likelihood of observing an artificial signal from that region of dense stars. If artificial transmitters are not common in the galaxy, then searching for a strong transmitter among the billions of stars in the disk of our galaxy is the best strategy, Simeon said.

Breakthrough Listen, based at UC Berkeley, collects petabytes of data from the Green Bank Telescope in West Virginia (right) and the Parkes radio telescope in Australia (left) and makes it available to the science community to analyze in search of signals from intelligent civilizations. (Graphic courtesy of Breakthrough Listen)

Breakthrough Listen, based at UC Berkeley, collects petabytes of data from the Green Bank Telescope in West Virginia (right) and the Parkes radio telescope in Australia (left) and makes it available to the science community to analyze in search of signals from intelligent civilizations. (Image: courtesy of Breakthrough Listen)

On the other hand, putting a powerful, intergalactic transmitter in the core of our galaxy, perhaps powered by the 4 million-solar-mass black hole there, might not be beyond the capabilities of a very advanced civilization. Galactic centers may be so-called Schelling points: likely places for civilizations to meet up or place beacons, given that they cannot communicate among themselves to agree on a location. Siemion said:

Visit from an interstellar comet

Breakthrough Listen also released observations of the interstellar comet 2I/Borisov, which had a close encounter with the Sun in December and is now on its way out of the solar system. The group had earlier scanned the interstellar rock ‘Oumuamua, which passed through the center of our solar system in 2017. Neither exhibited technosignatures.

NASA’s Hubble Space Telescope took this photo of the interstellar comet 2I/Borisov in October 2019, two months before its closest approach to the sun. (Photo courtesy of NASA, ESA and D. Jewitt, UCLA)

NASA’s Hubble Space Telescope took this photo of the interstellar comet 2I/Borisov in October 2019, two months before its closest approach to the Sun. (Image: courtesy of NASA, ESA, and D. Jewitt, UCLA)

Steve Croft, a research astronomer with the Berkeley SETI Research Center and Breakthrough Listen, said:

Regardless of the kind of SETI search, Siemion said, Breakthrough Listen looks for electromagnetic radiation that is consistent with a signal that we know technology produces, or some anticipated signal that technology could produce, and inconsistent with the background noise from natural astrophysical events. This also requires eliminating signals from cellphones, satellites, GPS, Internet, Wi-fi, and myriad other human sources.

In Sheikh’s case, she turned the Green Bank telescope on each star for five minutes, pointed away for another five minutes and repeated that twice more. She then threw out any signal that didn’t disappear when the telescope pointed away from the star. Ultimately, she whittled an initial 1 million radio spikes down to a couple hundred, which she was able to eliminate as Earth-based human interference. The last four unexplained signals turned out to be from passing satellites.

Siemion emphasized that the Breakthrough Listen team intends to analyze all the data released to date and to do it systematically and often, saying:

Breakthrough Listen, based at UC Berkeley, is supported by a $100 million, 10-year commitment from the Breakthrough Initiatives, founded in 2015 by Yuri and Julia Milner to explore the universe, seek scientific evidence of life beyond Earth, and encourage public debate from a planetary perspective.

Provided by: University of California – Berkeley [Note: Materials may be edited for content and length.]

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