  Flocking models with metric and topological interactions are supposed to
exhibit distinct features, as for instance the presence and absence of moving
polar bands. On the other hand, quenched disorder (spatial heterogeneities) has
been shown to dramatically affect large-scale properties of active systems with
metric interactions, while the impact of quenched disorder on active systems
with metric-free interactions has remained, until now, unexplored. Here, we
show that topological flocking models recover several features of metric ones
in homogeneous media, when placed in a heterogeneous environment. In
particular, we find that order is long-ranged even in the presence of spatial
heterogeneities, and that the heterogeneous environment induces an effective
density-order coupling facilitating emergence of traveling bands, which are
observed in wide regions of parameter space. We argue that such a coupling
results from a fluctuation-induced rewiring of the topological interaction
network, strongly enhanced by the presence of spatial heterogeneities.
