Effects of external global harmonic influence on chimera states

The effects of the global harmonic force on an ensemble of nonlocally coupled chaotic Rossler oscillators is studied. The autonomous ensemble without external force demonstrates a stable regime of chimera state. We have considered two types of the chimera states, namely phase chimera with a single incoherence cluster and combined chimera state with the incoherence clusters of the phase and amplitude chimeras. We have shown that even the sufficiently weak external influence leads to the qualitative changes in the spatiotemporal behavior of the ensemble under study. The diagram of regimes has been plotted in the plane of external signal parameters, where we detect regions with different dynamical regimes, induced by the external excitation. They are the spatiotemporal intermittence of structures, stable chimera states, stable regimes with a piecewise spatial profile, spatiotemporal chaos, complete chaotic synchronization and spatial incoherence. We have explored each of these regimes in detail and has found out that they are characterized by a certain distinctive range of the maximal Lyapunov exponent. We have found that the change of spatiotemporal behavior is not accompanied by the effects of locking the natural frequency or of suppression of selfoscillation by the external signal.