Key takeaways

  • Breakthrough listen’s latest SETI survey scanned for alien radio signals toward the galactic center.
  • Over 600 hours of radio observations were collected from two major radio telescopes.
  • The search focused on periodic radio transients, potential signs of alien beacons.
  • No evidence of extraterrestrial intelligence was detected, but magnetar activity was observed.
  • Despite no current findings, the search for intelligent life in the universe continues with new data and methods.
supermassive black hole parked in the core. Image: X-Ray:NASA/CXC/UMass/D. Wang et al.; Radio:NRF/SARAO/MeerKAT

Astrobiologists working on the Breakthrough Listen project have presented preliminary results from a SETI survey in which the team searched for radio signals along a line of sight that stretches toward the galactic center.

The quest for alien radio transmissions is already in its eighth decade, but we have yet to discover any evidence of sentient life. However, we must continue our search, since there is no bigger unanswered scientific enigma than whether or not we are alone in the cosmos.

The hunt for extraterrestrial intelligence, or SETI, is now restricted to the detection of alleged alien technosignatures such as optical and microwave communications and evidence of massive constructions. Nonetheless, radio signals remain the most common SETI target, as targeted radio emissions may indicate the presence of an extraterrestrial civilization, whether the leakage is intentional or unintentional.

The $10 million Breakthrough Listen project, a 10-year venture started six years ago by Israeli-Russian billionaire Yuri Milner and the late scientist Stephen Hawking, carries on this legacy by scouring the depths of space for traces of extraterrestrial radio waves.

The Breakthrough Listen team, located at the SETI Research Center at the University of California, Berkeley, collected over 600 hours of radio observations from the Green Bank Radio Telescope in West Virginia and the CSIRO’s Parkes Radio Telescope in Australia for its most recent survey. Their most recent endeavor was unusual in that it was the “most sensitive and deepest targeted SETI” scan yet done of the galactic core, according to SETI scientists in a report expected to be published in the Astronomical Journal (a preprint is now accessible on arXiv).

Looking for aliens along a line of sight that spans from Earth to the supermassive black hole at the heart of the Milky Way has both benefits and disadvantages.

The benefit is that the density of stars rises with distance from the galactic center. As a result, this line of sight “offers the largest number of potentially habitable systems of any direction in the sky,” according to the research. Furthermore, the relatively near proximity of these stars to each other may “accelerate development of interstellar communication and travel,” contributing to the establishment of “advanced space-faring societies,” according to the SETI experts’ research.

The negative is that things become a little hairy after a certain point. The Milky Way, like the solar system, contains a habitable zone beyond which no life can evolve. Indeed, the inner area of our galaxy (the region outside the galactic habitable zone) is a high-radiation environment teeming with gamma rays, exploding supernovae, and gas clouds reaching millions of degrees. The towering supermassive black hole at the galactic center poses an entirely other threat.

Nonetheless, the authors of the current study, lead by Vishal Gajjar of the Department of Astronomy at Berkeley, believed it would be beneficial to conduct a comprehensive search near the galactic center due to the sheer amount of stars from here to there. As the scientists saw in their study, “we estimated that we surveyed around 60 million stars.”

Interestingly, the team was not hunting for unintentional radio leakage, but rather for periodic radio transients emitted by hypothetical beacons. According to the scientists, the galactic center “provides an ideal” central position for “advanced civilizations to place a powerful transmitter to efficiently send beacons across the entire Milky Way,” adding additional benefit to this technique.

Gajjar and his colleagues scanned frequencies ranging from 0.7 to 93 GHz. The preliminary report’s results were confined to frequencies between 1 and 8 GHz and time intervals of 7 hours (as detected by Parkes) and 11.2 hours (as recorded by the Green Bay Telescope). There were no recurring radio blasts consistent with aliens beacon were detected within these parameters.

No extraterrestrial intelligences were discovered, but the scientists were able to catch transitory phenomena compatible with magnetars, which would be of interest to astronomers studying this sort of neutron star. Again, this is a preliminary study, so we anxiously anticipate further outcomes.

In 2019, the same team fell short after studying 1,372 neighboring stars. Despite our thorough efforts, we have yet to locate any signs of extraterrestrial life. It’s hard not to be negative about the entire SETI project, but keep in mind that the hunt for intelligent extraterrestrial species has only just begun.

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