Dynamical deviations from superrotation in hot Jupiters
There are currently two exoplanets that question the paradigm that the hottest spot of a hot Jupiter is always eastward shifted due to superrotation: CoRoT-2b with an apparent westward shift and HAT-P-7b, the hot spot of which appears to oscillate between east ward and westward shift. So far, non-synchronous rotation, magnetic effects or (changes in) partial cloud coverage were inferred as explanations of the apparent anomalies in the phase curves of CoRoT-2b abd HAT-P-7b.
We propose another possible explanation due to dynamical changes: Some of our 3D simulations show that superrotation on the day side can be dynamically disrupted. This effect is particularly pronounced for fast rotating hot Jupiters with high log g like WASP-43b. In fact, we reproduce the phase curve of WASP-43b with this dynamical effect relatively well. We don't need to increase metallicity or to infer additional effects like clouds, anomalous rotation or magnetic field interactions. Anomalous dynamics is apparently sufficient to at least dampen the eastward hot spot shift.