Measuring Transit Signal Recovery in the Kepler Pipeline. III. Completeness of the Q1-Q17 DR24 Planet Candidate Catalogue, with Important Caveats for Occurrence Rate Calculations

TL;DR

This study evaluates the detection efficiency of the Kepler pipeline version 9.2 by injecting simulated planets into data, revealing a strong period dependence and providing insights for accurate exoplanet occurrence rate calculations.

Contribution

It introduces a detailed measurement of the Kepler pipeline's sensitivity, highlighting period-dependent detection efficiency and offering guidance for occurrence rate analyses.

Findings

Detection efficiency decreases for periods longer than 40 days.

Pipeline sensitivity varies with planet signal strength and period.

Recommendations for accurate occurrence rate calculations are provided.

Abstract

With each new version of the Kepler pipeline and resulting planet candidate catalogue, an updated measurement of the underlying planet population can only be recovered with an corresponding measurement of the Kepler pipeline detection efficiency. Here, we present measurements of the sensitivity of the pipeline (version 9.2) used to generate the Q1-Q17 DR24 planet candidate catalog (Coughlin et al. 2016). We measure this by injecting simulated transiting planets into the pixel-level data of 159,013 targets across the entire Kepler focal plane, and examining the recovery rate. Unlike previous versions of the Kepler pipeline, we find a strong period dependence in the measured detection efficiency, with longer (>40 day) periods having a significantly lower detectability than shorter periods, introduced in part by an incorrectly implemented veto. Consequently, the sensitivity of the 9.2 pipeline cannot be cast as a simple one-dimensional function of the signal strength of the candidate planet signal as was possible for previous versions of the pipeline. We report on the implications for occurrence rate calculations based on the Q1-Q17 DR24 planet candidate catalog and offer important caveats and recommendations for performing such calculations. As before, we make available the entire table of injected planet parameters and whether they were recovered by the pipeline, enabling readers to derive the pipeline detection sensitivity in the planet and/or stellar parameter space of their choice.