  Many active biological particles, such as swimming microorganisms or
motor-proteins, do work on their environment by going though a periodic
sequence of shapes. Interactions between particles can lead to the
phase-synchronization of their duty cycles. Here we consider collective
dynamics in a suspension of such active particles coupled through
hydrodynamics. We demonstrate that the emergent non-equilibrium states feature
stationary patterned flows and robust unidirectional pumping states under
confinement. Moreover the phase-synchronized state of the suspension exhibits
spatially robust chimera patterns in which synchronized and phase-isotropic
regions coexist within the same system. These findings demonstrate a new route
to pattern formation and could guide the design of new active materials.
