AI Insight
This paper proposes using the upgraded ALMA2040 telescope array to search for extraterrestrial technological signatures in the millimetre and sub-millimetre wavelength range, a largely unexplored region of the electromagnetic spectrum for SETI. The authors outline four specific search strategies: detecting narrowband artificial signals with high drift rates, identifying broadband radiation leakage from advanced civilizations, locating waste heat from massive computational structures around M dwarf stars, and finding geometric patterns created by large-scale megastructures. These higher frequencies offer advantages including minimal interference from interstellar media, less terrestrial radio interference, and greater bandwidth efficiency for potential alien communication systems.
Why it matters
This work expands SETI methodology beyond traditional radio frequencies into a regime better suited for high-data-rate transmissions, potentially improving our chances of detecting technologically advanced civilizations. The proposed searches could identify various types of alien technology, from intentional communication beacons to unintentional energy waste signatures from massive computational infrastructure.
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⚠️ Preprint – Noch nicht peer-reviewed
Dieser Artikel wurde noch nicht von unabhängigen Experten begutachtet. Die Ergebnisse sind vorläufig und sollten mit Vorsicht interpretiert werden.
Abstract: The search for extraterrestrial intelligence (SETI) has been largely concentrated at centimetre wavelengths, and in particular in the ‘water hole’ (1.42-1.66 GHz) range. The millimetre and sub-millimetre sky is, by contrast, almost entirely unsearched. It also offers some natural advantages: above 35 GHz, the interstellar and interplanetary media are effectively transparent and non-dispersive, terrestrial interference is sparse, and interferometry suppresses what interference remains. Both antenna gain and usable fractional bandwidth increase with frequency, so a civilisation optimising directed, high-data-rate links has advantageous reasons to operate in this regime, as illustrated by the ongoing migration of our own telecommunications systems to much higher frequencies. Building on the first ALMA technosignature survey (Mason et al. 2025), we identify four searches ALMA2040 is uniquely placed to make: (i) narrowband searches using a phased-up, beamformed array, extending the commensal model pioneered for the VLA and MeerKAT into a regime where drift rates reach ~ 103 Hz s^-1; (ii) broadband aggregate leakage (BRaTs) from Kardashev Type I civilisations, for which 128-512 GHz of instantaneous bandwidth places a ~ 60 pc horizon within an integration time of one hour on source; (iii) Dysonian searches for the cold waste heat of computation – Slysh haloes – whose arcsecond and subarcsecond angular scales around M dwarfs are well matched to ALMA2040’s array configuration; and (iv) geometric discontinuities imprinted by occulting megastructures, detectable as ringing in the visibility function with a phased ALMA operating in a mm/sub-mm VLBI array. We set out the corresponding requirements: bandwidth, beamforming, commensal access, spectral resolution and sub-second time resolution.
Source: Millimetre/Sub-Millimetre SETI: Expanding the Radio Technosignature Parameter Space with ALMA2040