GBT data extends SETI search to extragalactic distances

An international team of astronomers has extended the reach of the Search for Extraterrestrial Intelligence (SETI) Breakthrough Listen project, thanks to data from the National Science Foundation’s Green Bank Telescope (GBT.)

Photo credit Dave Green.

The search for technosignatures, signals created by extraterrestrial intelligent life, often focuses on relatively nearby stars in our Milky Way Galaxy. A new approach will review existing data, but rather than looking at single stars, the new technique will instead focus on.distant galaxies, galaxy groups and galaxy clusters that contain hundreds of billions of stars that could host potentially habitable planets.

Breakthrough Listen has not yet detected technosignatures in its previous surveys. This challenge has revealed an important lesson – what not to look for. By placing new limits on the prevalence of very powerful radio transmitters in galaxies and other cosmic objects (and removing them from the search), a very bright signal created by extraterrestrial intelligence just might be revealed.

This search unites the efforts of Professor Michael Garrett of the University of Manchester (UK) with University of Berkeley SETI Director Dr. Andrew Siemion, a Visiting Professor at Manchester. Garett and Siemion reviewed 469 target fields previously observed by the GBT, identifying more than 140,000 extragalactic systems located outside our Milky Way.

An optical colour image of the stellar field centred on a nearby star targeted by BL (HIP 71181, about 43 light years distant) showing the extent of the Green Bank Telescope beam circled in red. Members of a galaxy cluster 640 million lightyears distant are identified with the white circles. Yellow circles indicate cluster members outside the nominal sensitivity area of the Green Bank Telescope. Other indicated extragalactic objects include two quasi-stellar objects (QSOs) and an active galactic nuclei (AGN). Read more about this in SETI’s original post.

Their paper, “Constraints on extragalactic transmitters via Breakthrough Listen observations of background sources” will be published in the Monthly Notices of the Royal Astronomical Society. A preprint and supplementary material, including figures, are available at seti.berkeley.edu/extragalactic. This research was also shared this month at the 2022 International Astronautical Congress in Paris, France.

The Jodrell Bank Center for Astrophysics is one of the largest astrophysics university departments in Europe. As part of the Department of Physics & Astronomy at the University of Manchester, the Centre conducts an extensive research program ranging from the study of the origin of the Universe in the Big Bang to the discovery of planets orbiting other stars. The Center comprises 200 staff and postgraduate students, and is responsible for operating the telescope facilities at

Breakthrough Listen is a scientific program in search for evidence of technological life in the Universe. It aims to survey one million nearby stars, the entire galactic plane and 100 nearby galaxies at a wide range of radio and optical bands.

The Green Bank Observatory is a facility of the National Science Foundation and is operated by Associated Universities, Inc.

This information was adapted from a press release shared by the University of Manchester and SETI.