Synchronization in Networks with Strongly Delayed Couplings

We investigate the stability of synchronization in networks of dynamical systems with strongly delayed connections. We obtain strict conditions for synchronization of periodic and equilibrium solutions. In particular, we show the existence of a critical coupling strength $\kappa_{c}$, depending only on the network structure, isolated dynamics and coupling function, such that for large delay and coupling strength $\kappa<\kappa_{c}$, the network possesses stable synchronization. The critical coupling $\kappa_{c}$ can be chosen independently of the delay for the case of equilibria, while for the periodic solution, $\kappa_{c}$ depends essentially on the delay and vanishes as the delay increases. We observe that, for random networks, the synchronization interval is maximal when the network is close to the connectivity threshold. We also derive scaling of the coupling parameter that allows for a synchronization of large networks for different network topologies.