Exoplanet transit search at the detection limit: detection and false alarm vetting pipeline

TL;DR

This paper introduces a new pipeline for detecting Earth-like exoplanets in Kepler data, improving reliability at the detection limit and effectively distinguishing true planets from false alarms.

Contribution

The paper presents a novel detection and vetting pipeline with enhanced defect removal, a Bayesian test statistic, and multi-candidate extraction, improving detection accuracy at low signal levels.

Findings

Improved pipeline completeness at fixed false alarm rate.

Successfully recovers known planet candidates.

Flags many unconfirmed candidates as false alarms.

Abstract

One of the primary mission goals of the Kepler space telescope was to detect Earth-like terrestrial planets in the habitable zone around Sun-like stars. These planets are at the detection limit, where the Kepler detection and vetting pipeline produced unreliable planet candidates. We present a novel pipeline that improves the removal of localized defects prior to the planet search, improves vetting at the level of individual transits and introduces a Bayes factor test statistic and an algorithm for extracting multiple candidates from a single detection run. We show with injections in the Kepler data that the introduced novelties improve pipeline's completeness at a fixed false alarm rate. We apply the pipeline to the stars with previously identified planet candidates and show that our pipeline successfully recovers the previously confirmed candidates, but flags a considerable portion of unconfirmed candidates as likely false alarms, especially in the long period, low signal-to-noise ratio regime. In particular, several known Earth-like candidates in the habitable zone, such as KOI 8063.01, 8107.01 and 8242.01, are identified as false alarms, which could have a significant impact on the estimates of $\eta_{\oplus}$, i.e., the occurrence of Earth-like planets in the habitable zone.