  Chimera states are an example of intriguing partial synchronization patterns
emerging in networks of identical oscillators. They consist of spatially
coexisting domains of coherent (synchronized) and incoherent (desynchronized)
dynamics. We analyze chimera states in networks of Van der Pol oscillators with
hierarchical connectivities, and elaborate the role of time delay introduced in
the coupling term. In the parameter plane of coupling strength and delay time
we find tongue-like regions of existence of chimera states alternating with
regions of existence of coherent travelling waves. We demonstrate that by
varying the time delay one can deliberately stabilize desired spatio-temporal
patterns in the system.
