SETI & Technosignatures

The Breakthrough Listen Search for Intelligent Life: Detection and Characterization of Anomalous Transits in Kepler Lightcurves

By Keith Cowing

Status Report

astro-ph.EP

December 13, 2023

Filed under astro-ph.EP

The Breakthrough Listen Search for Intelligent Life: Detection and Characterization of Anomalous Transits in Kepler Lightcurves — Scatter plot demonstrating injection and recovery accuracy for a sample lightcurve. Each point represents the injected properties of recovered transits. In the left-hand plot, orange triangles represent transits flagged for large TTVs, and the orange filled area represents the region of parameter space which should produce a TTV flag. In the right-hand plot, orange triangles represent transits flagged as missing, blue squares represent transits flagged for large depths, and the orange and blue regions represent the corresponding regions of parameter space expected to produce flags. Not all transits injected in the shaded regions are flagged due to imperfect recovery of the injected properties. — astro-ph.EP

Never before has the detection and characterization of exoplanets via transit photometry been as promising and feasible as it is now, due to the increasing breadth and sensitivity of time domain optical surveys.

Past works have made use of phase-folded stellar lightcurves in order to study the properties of exoplanet transits, because this provides the highest signal that a transit is present at a given period and ephemeris. Characterizing transits on an individual, rather than phase-folded, basis is much more challenging due to the often low signal-to-noise ratio (SNR) of lightcurves, missing data, and low sampling rates. However, by phase-folding a lightcurve we implicitly assume that all transits have the same expected properties, and lose all information about the nature and variability of the transits.

We miss the natural variability in transit shapes, or even the deliberate or inadvertent modification of transit signals by an extraterrestrial civilization (for example, via laser emission or orbiting megastructures). In this work, we develop an algorithm to search stellar lightcurves for individual anomalous (in timing or depth) transits, and we report the results of that search for 218 confirmed transiting exoplanet systems from Kepler.

Anna Zuckerman, James Davenport, Steve Croft, Andrew Siemion, Imke de Pater

Comments: 11 pages, 8 figures. Accepted to The Astronomical Journal
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Cite as: arXiv:2312.07903 [astro-ph.EP] (or arXiv:2312.07903v1 [astro-ph.EP] for this version)
Submission history
From: Anna Zuckerman
[v1] Wed, 13 Dec 2023 05:21:44 UTC (2,182 KB)
https://arxiv.org/abs/2312.07903

Astrobiology, SETI,

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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