The Hunt for Exomoons with Kepler (HEK): V. A Survey of 41 Planetary Candidates for Exomoons
Abstract
We present a survey of 41 Kepler Objects of Interest (KOIs) for exomoons using Bayesian photodynamics, more than tripling the number of KOIs surveyed with this technique. We find no compelling evidence for exomoons although 13 KOIs yield spurious detections driven by instrumental artifacts, stellar activity, and/or perturbations from unseen bodies. Regarding the latter, we find seven KOIs exhibiting >5 σ evidence of transit timing variations, including the “megaEarth” Kepler10c, likely indicating an additional planet in that system. We exploit the moderately large sample of 57 unique KOIs surveyed to date to infer several useful statistics. For example, although there is a diverse range in sensitivities, we find that we are sensitive to PlutoCharon massratio systems for ≃40% of KOIs studied and EarthMoon massratios for 1 in 8 cases. In terms of absolute mass, our limits probe down to 1.7 Ganymede masses, with a sensitivity to Earthmass moons for 1 in 3 cases studied and to the smallest moons capable of sustaining an Earthlike atmosphere (0.3 M_{⨁}) for 1 in 4. Despite the lack of positive detections to date, we caution against drawing conclusions yet, since our most interesting objects remain under analysis. Finally, we point out that had we searched for the photometric transit signals of exomoons alone, rather than using photodynamics, we estimate that 1 in 4 KOIs would have erroneously been concluded to harbor exomoons due to residual time correlated noise in the Kepler data, posing a serious problem for alternative methods.
Based on archival data of the Kepler telescope.
 Publication:

The Astrophysical Journal
 Pub Date:
 November 2015
 DOI:
 10.1088/0004637X/813/1/14
 arXiv:
 arXiv:1503.05555
 Bibcode:
 2015ApJ...813...14K
 Keywords:

 planetary systems;
 techniques: photometric;
 Astrophysics  Earth and Planetary Astrophysics
 EPrint:
 18 pages, 9 figures, 4 tables. Accepted in ApJ