SETI & Technosignatures

A Search For Radio Technosignatures At The Solar Gravitational Lens Targeting Alpha Centauri

By Keith Cowing
June 30, 2022
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A Search For Radio Technosignatures At The Solar Gravitational Lens Targeting Alpha Centauri
View of the solar system from a probe opposite α Cen at 550 AU on the night of our observations. The Sun lies at the origin, and the inner solar system planets’ orbits are shown. Gray filled circles indicate beam widths for various transmitter diameters at 10-cm wavelengths. For a probe located at a distance d > 550 AU, these orbital axes would scale down by a factor of d/(550 AU).

Stars provide an enormous gain for interstellar communications at their gravitational focus, perhaps as part of an interstellar network. If the Sun is part of such a network, there should be probes at the gravitational foci of nearby stars.

If there are probes within the solar system connected to such a network, we might detect them by intercepting transmissions from relays at these foci. Here, we demonstrate a search across a wide bandwidth for interstellar communication relays beyond the Sun’s innermost gravitational focus at 550 AU using the Green Bank Telescope (GBT) and Breakthrough Listen (BL) backend. As a first target, we searched for a relay at the focus of the Alpha Centauri AB system while correcting for the parallax due to Earth’s orbit around the Sun.

We searched for radio signals directed at the inner solar system from such a source in the L and S bands. Our analysis, utilizing the turboSETI software developed by BL, did not detect any signal indicative of a non-human-made artificial origin.

Further analysis excluded false negatives and signals from the nearby target HD 13908. Assuming a conservative gain of 10^3 in L-band and roughly 4 times that in S-band, a ~1 meter directed transmitter would be detectable by our search above 7 W at 550 AU or 23 W at 1000 AU in L-band, and above 2 W at 550 AU or 7 W at 1000 AU in S-band. Finally, we discuss the application of this method to other frequencies and targets.

Nick Tusay, Macy J. Huston, Cayla M. Dedrick, Stephen Kerby, Michael L. Palumbo III, Steve Croft, Jason T. Wright, Paul Robertson, Sofia Sheikh, Laura Duffy, Gregory Foote, Andrew Hyde, Julia Lafond, Ella Mullikin, Winter Parts, Phoebe Sandhaus, Hillary H. Smith, Evan L. Sneed, Daniel Czech, Vishal Gajjar

Comments: 20 pages, 9 figures, accepted to AJ
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2206.14807 [astro-ph.IM] (or arXiv:2206.14807v1 [astro-ph.IM] for this version)
Submission history
From: Macy Huston
[v1] Tue, 28 Jun 2022 13:22:11 UTC (7,471 KB)
Astrobiology, SETI,

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) 🖖🏻