Enhancing gravitational wave anisotropies with peaked scalar sources
  Gravitational wave (GW) backgrounds of cosmological origin are expected to be
nearly isotropic, with small anisotropies resembling those of the cosmic
microwave background. We analyse the case of a scalar-induced GW background and
clarify in the process the relation between two different approaches to
calculating GW anisotropies. We focus on GW scenarios sourced by a
significantly peaked scalar spectrum, which are frequently considered in the
context of primordial black holes production. We show that the resulting GW
anisotropies are characterised by a distinct frequency dependence. We explore
the observational consequences concentrating on a GW background enhanced in the
frequency band of space-based GW detectors. We study the detectability of the
signal through both cross-correlations among different space-based GW
detectors, and among GW and CMB experiments.
