# The Kepler Peas in a Pod Pattern is Astrophysical

## TL;DR

This study demonstrates that the observed 'peas in a pod' pattern of Kepler planets is astrophysical in origin and not caused by detection bias, using direct sampling of planet radii and a sensitivity model.

## Contribution

The paper refutes previous claims that detection bias creates the 'peas in a pod' pattern by showing sampling transit SNR is invalid and directly modeling planet radii confirms the pattern's astrophysical nature.

## Key findings

- Detection bias is not responsible for the 'peas in a pod' pattern.
- Sampling transit SNR is unsuitable for testing detection bias.
- The pattern is confirmed to be astrophysical with >10-sigma confidence.

## 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.