SETI & Technosignatures

A Green Bank Telescope Search For Narrowband Technosignatures Between 1.1-1.9 GHz During 12 Kepler Planetary Transits

By Keith Cowing
Press Release
December 13, 2022
Filed under , , , ,
A Green Bank Telescope Search For Narrowband Technosignatures Between 1.1-1.9 GHz During 12 Kepler Planetary Transits
a) An example of an event in the 1165–1185 MHz region, consistent with GPS L5. This event is RFI, as it appears in multiple different targets in consecutive observations. The dashed red line represents turboSETI’s best-fit drift rate for the detected hit. b) An example of an event in the 1375–1385 MHz region. These events occur for only a fraction of the observation (here, about 100 seconds) within a single scan — this makes it difficult to determine whether they are impulsive RFI or whether they are true transient signals localized on the sky. However, because we observe the same morphology of signal in multiple targets, and because of the match to the GPS L3 downlink, we can assign these events as RFI. c) An example of an event in the 1570–1580 MHz region. These events are similar to the example shown in subfigure b in that they are degenerate between transient and localized signals; this is a common challenge for single-dish technosignature searches. The same signals were identified in multiple targets, however, indicating that they are indeed RFI — likely the GPS L1 downlink. d) An example of a high-drift rate signal around 1626 MHz. We attribute this event to an Iridium satellite. It is clearly present in all three panels, and therefore RFI, but the changing slope of the signals over time confounds the linear search algorithm. — astro-ph.EP

A growing avenue for determining the prevalence of life beyond Earth is to search for “technosignatures” from extraterrestrial intelligences/agents.

Technosignatures require significant energy to be visible across interstellar space and thus intentional signals might be concentrated in frequency, in time, or in space, to be found in mutually obvious places. Therefore, it could be advantageous to search for technosignatures in parts of parameter space that are mutually-derivable to an observer on Earth and a distant transmitter.

In this work, we used the L-band (1.1-1.9 GHz) receiver on the Robert C. Byrd Green Bank Telescope (GBT) to perform the first technosignature search pre-synchronized with exoplanet transits, covering 12 Kepler systems. We used the Breakthrough Listen turboSETI pipeline to flag narrowband hits (∼3 Hz) using a maximum drift rate of ±614.4 Hz/s and a signal-to-noise threshold of 5 – the pipeline returned ∼3.4×105 apparently-localized features.

Visual inspection by a team of citizen scientists ruled out 99.6% of them. Further analysis found 2 signals-of-interest that warrant follow-up, but no technosignatures. If the signals-of-interest are not re-detected in future work, it will imply that the 12 targets in the search are not producing transit-aligned signals from 1.1-1.9 GHz with transmitter powers >60 times that of the former Arecibo radar.

This search debuts a range of innovative technosignature techniques: citizen science vetting of potential signals-of-interest, a sensitivity-aware search out to extremely high drift rates, a more flexible method of analyzing on-off cadences, and an extremely low signal-to-noise threshold.

Sofia Z. Sheikh, Shubham Kanodia, Emily Lubar, William P. Bowman, Caleb I. Cañas, Christian Gilbertson, Mariah G. MacDonald, Jason Wright, David MacMahon, Steve Croft, Danny Price, Andrew Siemion, Jamie Drew, S. Pete Worden, Elizabeth Trenholm

Comments: 18 pages, 11 figures
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Cite as: arXiv:2212.05137 [astro-ph.EP] (or arXiv:2212.05137v1 [astro-ph.EP] for this version)
Submission history
From: Sofia Sheikh
[v1] Fri, 9 Dec 2022 22:31:03 UTC (3,337 KB)

Astrobiology, SETI,

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