Robust detection limit for Kepler transit-timing variations

Establish a robust detection limit for planetary transit-timing-variation signals in Kepler data by incorporating instrumental and astrophysical effects into synthetic transit midtimes and determining the parameter space in which planetary TTV signals can be distinguished from other sources.

Background

The analysis assumes that TTV signals with amplitudes greater than 10 minutes would be detected by Kepler, but the authors emphasize that this threshold has not been validated. Detection depends on stellar activity, the method used to determine transit midtimes, instrumental effects, and the frequencies introduced by these effects.

A reliable detection limit would require injecting realistic instrumental and astrophysical effects into ExoMOD-generated transit times and recomputing the inferred TTVs. Such a calibration is necessary for quantitatively comparing the predicted and observed TTV populations and for identifying the source of the short-period TTV excess.

References

As a reference point, we assumed that TTV signals with $A_{\rm TTV}>10$ min would be detected; however, it remains unclear whether this threshold is appropriate. Establishing a robust TTV detection limit would require the development of a realistic model incorporating the instrumental and astrophysical effects discussed above.

— ExoMOD II. A Statistical Model of Transit Timing Variations in Kepler Multi-Planet Systems  (2608.28550 - Nesvorny et al., 28 Aug 2026) in Section 4, paragraph beginning “A major limitation of this work”