SETI & Technosignatures

Conducting High Frequency Radio SETI Using ALMA

By Keith Cowing

Status Report

astro-ph.IM

December 2, 2024

Filed under ALMA, astro-ph.IM, Gaia DR3 catalog, Interferometer, SETI, telescope

Conducting High Frequency Radio SETI Using ALMA — Comparison of the potential sensitivity of telescopes to perform SETI searches for narrowband transmitters against frequency coverage (following Siemion et al. (2014) & Croft et al. (2018)). The telescope’s minimum detectable 𝐸 𝐼𝑅𝑃𝑚𝑖𝑛 is based on an integration time of 10 minutes, a significance threshold of 15, channel width of 0.5 Hz and distances up to 15 pc. ALMA operates at a higher frequency range than previously explored and is sensitive to radio powers similar to the Arecibo planetary radar system. astro-ph.IM

The Atacama Millimeter/Submillimeter Array (ALMA) remains unparalleled in sensitivity at radio frequencies above 35 GHz.

In this paper, we explore ALMA’s potential for narrowband technosignature detection, considering factors such as the interferometer’s undistorted field of view, signal dilution due to significant drift rates at high frequencies and the possibility of spectral confusion.

We present the first technosignature survey using archival ALMA data in Band 3, focusing on two spectral windows centred on 90.642 GHz and 93.151 GHz. Our survey places new limits at these frequencies on the prevalence of extraterrestrial transmitters for 28 galactic stars, selected from the Gaia DR3 catalogue.

We employ a stellar ‘bycatch’ method to sample these objects within the undistorted field of view of four ALMA calibrators. For the closest star in our sample, we find no evidence of transmitters with EIRP_min > 7 x 10^17 W. To the best of our knowledge, this represents the first technosignature search conducted using ALMA data.

The 𝐸 𝐼𝑅𝑃𝑚𝑖𝑛 and transmitter rate for a sample of SETI surveys above 1 GHz, including our own work using ALMA (amended from figure by Tremblay et al. (2023)). The EIRP can be compared against potential limits for an Arecibo planetary radar (1013W) and a Kardashev Type I civilisation (1017W). The suggested ’Terra Incognito’ limit – denoted in the slanted gray line – challenges the limits of telescopes and the breadth of surveys conducted to date. — astro-ph.IM

Louisa A Mason (1), Michael A Garrett (1,2), Kelvin Wandia (1), Andrew P V Siemion (1,3,4,5,6) ((1) Jodrell Bank Centre for Astrophysics, University of Manchester, (2) Leiden Observatory, Leiden University (3) Astrophysics Sub-Department, Department of Physics, University of Oxford, (4) SETI Institute, (5) Berkeley SETI Research Centre, University of California, (6) University of Malta)

Comments: 9 pages, 5 figures, submitted to MNRAS
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Astrophysics of Galaxies (astro-ph.GA)
Cite as: arXiv:2411.19827 [astro-ph.IM] (or arXiv:2411.19827v1 [astro-ph.IM] for this version)
https://doi.org/10.48550/arXiv.2411.19827
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Submission history
From: Louisa Mason
[v1] Fri, 29 Nov 2024 16:41:26 UTC (7,609 KB)
https://arxiv.org/abs/2411.19827

Astrobiology,

Keith Cowing

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻

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