Probing Primordial Black Holes with Anisotropies in Stochastic
  Gravitational-Wave Background
  Primordial black holes, if considered to constitute a significant fraction of
cold dark matter, trace the inhomogeneous large-scale structure of the
Universe. Consequently, the stochastic gravitational-wave background,
originating from incoherent superposition of unresolved signals emitted by
primordial black hole binaries, is expected to display anisotropies across the
sky. In this work, we investigate the angular correlations of such anisotropies
for the first time and demonstrate their difference from the analogous signal
produced by astrophysical black hole binaries. We carefully evaluate the
associated uncertainties due to shot-noise and cosmic variance, and demonstrate
that the studied signal in the low-frequency regime can be differentiated from
the signal of astrophysical origin. Our results are particularly promising in
the stellar mass-range, where the identification of the merger origin has been
particularly challenging.
