On the Low False Positive Probabilities of Kepler Planet Candidates
Abstract
We present a framework to conservatively estimate the probability that any particular planetlike transit signal observed by the Kepler mission is in fact a planet, prior to any groundbased followup efforts. We use Monte Carlo methods based on stellar population synthesis and Galactic structure models, and report false positive probabilities (FPPs) for every Kepler Object of Interest, assuming a 20% intrinsic occurrence rate of closein planets in the radius range 0.5 R _{⊕} < R_{p} < 20 R _{⊕}. Nearly 90% of the 1235 candidates have FPP <10%, and over half have FPP <5%. This probability varies with the magnitude and Galactic latitude of the target star, and with the depth of the transit signal—deeper signals generally have higher FPPs than shallower signals. We establish that a single deep highresolution image will be an effective followup tool for the shallowest (Earthsized) transits, providing the quickest route toward probabilistically validating the smallest candidates by potentially decreasing the FPP of an Earthsized transit around a faint star from >10% to <1%. Since Kepler has detected many more planetary signals than can be positively confirmed with groundbased followup efforts in the near term, these calculations will be crucial to using the ensemble of Kepler data to determine population characteristics of planetary systems. We also describe how our analysis complements the Kepler team's more detailed BLENDER false positive analysis for planet validation.
 Publication:

The Astrophysical Journal
 Pub Date:
 September 2011
 DOI:
 10.1088/0004637X/738/2/170
 arXiv:
 arXiv:1101.5630
 Bibcode:
 2011ApJ...738..170M
 Keywords:

 methods: statistical;
 planets and satellites: general;
 stars: statistics;
 Astrophysics  Earth and Planetary Astrophysics;
 Astrophysics  Solar and Stellar Astrophysics
 EPrint:
 Revision including results of calculations of individual FPPs for all KOIs as well as an additional discussion section regarding the relationship of our calculations to BLENDER. ApJ in press