Search for Extragalactic Technosignatures With MeerKAT

Astrobiology explores the origins and evolution of life, with the Search for Extraterrestrial Intelligence (SETI) traditionally focused on detecting technosignatures within the Milky Way. The historical non-detection of technosignatures over the past sixty years may be attributed to the limited scope of searches, which have predominantly targeted individual stars within the Milky Way. This study expands SETI efforts to galaxy clusters, considering the potential for more advanced civilizations as proposed by the Kardashev scale. This method enables us to observe roughly ten orders of magnitude more stars than surveys that focus on individual stars in the Milky Way. By targeting galaxy clusters, we aim to enhance our ability to detect potential technosignatures, although the luminosity function of extraterrestrial radio transmitters remains unknown. Using the MeerKAT telescope in South Africa, we analyzed data from twenty galaxy clusters observed between July and September 2023. The data was processed using the Breakthrough Listen User Supplied Equipment (BLUSE) to identify narrowband radio signals, which are indicative of artificial origins. Although no definitive alien signals were confirmed, our findings enabled us to establish a new upper limit on the frequency of alien transmitters, tightening the constraint by an order of magnitude compared to our prior work (Uno et al. 2023). This observation marks the first-ever SETI exploration of galaxy clusters, setting the tightest upper limit on the transmitter rate. This pioneering effort significantly expands our search scope beyond the Milky Way, enhancing the potential for discovering advanced extraterrestrial life. Although no signals have been detected thus far, this research opens a new frontier in the quest for intelligent life beyond our galaxy.