Chimera state on a spherical surface of nonlocally coupled oscillators with heterogeneous phase lags.

We consider a network of coupled oscillators embedded in the surface of a sphere with nonlocal coupling strength and heterogeneous phase lags. A nonlocal coupling scheme with heterogeneous phase lags that allows the system to be solved analytically is suggested and the main effects of heterogeneity in the phase lags on the existence and stability of steady states are analyzed. We explore the stability of solutions along the Ott-Antonsen invariant manifold and present a complete bifurcation diagram for stationary patterns including the coherent, incoherent, and modulated drift states as well as chimera state. The stability analysis shows that a continuum of uniform drift states and the modulated drift state could become stable only due to the heterogeneity of the phase lags and that the chimera state is bifurcated from the modulated drift state. Our theoretical results are verified by using the direct numerical simulations of the model system.