title: Reentrant synchronization and pattern formation in pacemaker-entrained Kuramoto oscillators.
abstract: We study phase entrainment of Kuramoto oscillators under different conditions on the interaction range and the natural frequencies. In the first part the oscillators are entrained by a pacemaker acting like an impurity or a defect. We analytically derive the entrainment frequency for arbitrary interaction range and the entrainment threshold for all-to-all couplings. For intermediate couplings our numerical results show a reentrance of the synchronization transition as a function of the coupling range. The origin of this reentrance can be traced back to the normalization of the coupling strength. In the second part we consider a system of oscillators with an initial gradient in their natural frequencies, extended over a one-dimensional chain or a two-dimensional lattice. Here it is the oscillator with the highest natural frequency that becomes the pacemaker of the ensemble, sending out circular waves in oscillator-phase space. No asymmetric coupling between the oscillators is needed for this dynamical induction of the pacemaker property nor need it be distinguished by a gap in the natural frequency.
authors.affiliation: School of Engineering and Science, International University Bremen, P.O. Box 750561, D-28725 Bremen, Germany. f.radicchi@iu-bremen.de
authors.forename: Filippo
authors.initials: F
authors.lastname: Radicchi
authors.forename: Hildegard
authors.initials: H
authors.lastname: Meyer-Ortmanns