  The emergence and nature of amplitude mediated chimera states,
spatio-temporal patterns of co-existing coherent and incoherent regions, are
investigated for a globally coupled system of active and inactive
Ginzburg-Landau oscillators. The existence domain of such states is found to
shrink and shift in parametric space as the fraction of inactive oscillators is
increased. The role of inactive oscillators is found to be two fold - they get
activated to form a separate region of coherent oscillations and in addition
decrease the common collective frequency of the coherent regions by their
presence. The dynamical origin of these effects is delineated through a
detailed bifurcation analysis of a reduced model equation that is based on a
mean field approximation. Our results may have practical implications for the
robustness of such states in biological or physical systems where age related
deterioration in the functionality of components can occur.
