The Kepler Peas in a Pod Pattern is Astrophysical

Abstract

\Kepler\ planets around a given star have similar sizes to each other and regular orbital spacing, like "peas in a pod." Several studies have tested whether detection bias could produce this apparent pattern by resampling planet radii at random and applying a sensitivity function analogous to that of the Kepler spacecraft. However, \citet{Zhu2019} argues that this pattern is not astrophysical but an artifact of Kepler's discovery efficiency at the detection threshold. To support this claim, their new analysis samples the transit signal-to-noise ratio (SNR) to derive a synthetic population of bootstrapped planet radii. Here, we examine the procedure of sampling transit SNR and demonstrate it is not applicable. Sampling transit SNR does not set up random, independent planet radii, and so it is unsuitable for corroborating (or falsifying) detection bias as the origin of apparent patterns in planet radius. By sampling the planet radii directly and using a simple model for Kepler's sensitivity, we rule out detection bias as the source of the peas-in-a-pod pattern with $>10$-$\sigma$ confidence.

Accepted for publication in ApJ Letters; 11 pages, 4 figures

References in corpus (7)

• The Exoplanet Population Observation Simulator. I - The Inner Edges of Planetary Systems
• Exoplanet Orbital Eccentricities Derived From LAMOST-Kepler Analysis
• Kepler Multi-Planet Systems Exhibit Unexpected Intra-system Uniformity in Mass and Radius
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• The multiplicity distribution of Kepler's exoplanets
• On the patterns observed in Kepler multi-planet systems
• Accounting for Multiplicity in Calculating Eta Earth

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• The New Generation Planetary Population Synthesis (NGPPS). VI. Introducing KOBE: Kepler Observes Bern Exoplanets. Theoretical perspectives on the architecture of planetary systems: Peas in a pod
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