  Self-organized coherence-incoherence patterns, called chimera states, have
first been reported in systems of Kuramoto oscillators. For coupled excitable
units similar patterns, where coherent units are at rest, are called bump
states. Here, we study bumps in an array of active rotators coupled by
non-local attraction and global repulsion. We demonstrate how they can emerge
in a supercritical scenario from completely coherent Turing patterns: single
incoherent units appear in a homoclinic bifurcation with a subsequent
transition via quasiperiodic and chaotic behavior, eventually transforming into
extensive chaos with many incoherent units. We present different types of
transitions and explain the formation of coherence-incoherence patterns
according to the classical paradigm of short-range activation and long-range
inhibition.
