  We consider a system of independent point-like particles performing a
Brownian motion while interacting with a Gaussian fluctuating background. These
particles are in addition endowed with a discrete two-state internal degree of
freedom that is subjected to a nonequilibrium source of noise, which affects
their coupling with the background field. We explore the phase diagram of the
system and pinpoint the role of the nonequilibrium drive in producing a
nontrivial patterned spatial organization. We are able, by means of a weakly
nonlinear analysis, to account for the parameter-dependence of the boundaries
of the phase and pattern diagram in the stationary state.
