SETI & Technosignatures

The Breakthrough Listen Search for Intelligent Life: A Laser Search Pipeline for the Automated Planet Finder

By Keith Cowing
Status Report
January 17, 2023
Filed under , , , , ,
The Breakthrough Listen Search for Intelligent Life: A Laser Search Pipeline for the Automated Planet Finder
Stellar properties derived from APF spectra using the SpecMatch-Emp algorithm and subsequent isochrone analysis for stars within the library bounds (blue star shapes), compared to the properties for the same stars as reported in the Gaia catalog (green crosses). The library stars are also shown for reference (orange crosses). The matching algorithm inherently pulls the derived properties towards the library stars because all matches must come from within the library. The lack of stars cooler than Teff ≈ 4800 K reflects the magnitude limit of the APF. — astro-ph.IM

The Search for Extraterrestrial Intelligence (SETI) has traditionally been conducted at radio wavelengths, but optical searches are well-motivated and increasingly feasible due to the growing availability of high-resolution spectroscopy.

We present a data analysis pipeline to search Automated Planet Finder (APF) spectroscopic observations from the Levy Spectrometer for intense, persistent, narrow bandwidth optical lasers.

We describe the processing of the spectra, the laser search algorithm, and the results of our laser search on 1983 spectra of 388 stars as part of the Breakthrough Listen search for technosignatures.

We utilize an empirical spectra-matching algorithm called SpecMatch-Emp to produce residuals between each target spectrum and a set of best-matching catalog spectra, which provides the basis for a more sensitive search than previously possible.

We verify that SpecMatch-Emp performs well on APF-Levy spectra by calibrating the stellar properties derived by the algorithm against the SpecMatch-Emp library and against Gaia catalog values.

We leverage our unique observing strategy, which produces multiple spectra of each target per night of observing, to increase our detection sensitivity by programmatically rejecting events which do not persist between observations. With our laser search algorithm we achieve a sensitivity equivalent to the ability to detect an 84 kW laser at the median distance of a star in our dataset (78.5 ly).

We present the methodology and vetting of our laser search, finding no convincing candidates consistent with potential laser emission in our target sample.

Anna Zuckerman, Zoe Ko, Howard Isaacson, Steve Croft, Danny Price, Matt Lebofsky, Andrew Siemion

Comments: 24 pages, 12 figures. Accepted to The Astronomical Journal
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:2301.06971 [astro-ph.IM] (or arXiv:2301.06971v1 [astro-ph.IM] for this version)
Submission history
From: Anna Zuckerman
[v1] Tue, 17 Jan 2023 15:47:36 UTC (3,361 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) 🖖🏻