  We present a theory and computation method of radiation pressure from
partially coherent light by establishing a coherent mode representation of the
radiation forces. This is illustrated with the near field emitted from a
Gaussian Schell model source, mechanically acting on a single cylinder with
magnetodielectric behavior, or on a photonic molecule constituted by a pair of
such cylinders. Thus after studying the force produced by a single particle, we
address the effects of the spatial coherence on the bonding and anti-bonding
states of two particles. The coherence length manifests the critical limitation
of the contribution of evanescent modes to the scattered fields, and hence to
the nature and strength of the electromagnetic fores, even when electric and/or
magnetic partial wave resonances are excited.
