Confirming and Constraining Kepler Planets via Transit Timing Variations

Of the Kepler planets that have been reported to date, a significant fraction are in systems with multiple transiting planet.  In some cases, the signature of the gravitational interactions between planets in these systems can be seen in the variations of their times of transit. By carefully modeling the transit times, as well as investigating long-term stability, we are able to measure or constrain the masses and orbits of the transiting bodies in some of these systems, verifying that they are indeed planets. Although this approach is particularly effective for closely packed and near-resonant systems, it has also been applied to a broad range of systems. These include circumbinary planets, as well as systems with additional non-transiting planets. I review the process of using transit timing variations to confirm Kepler planets, highlighting some examples of dynamically interesting systems.