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Abstract

We investigate the discrepancy pointed out by Jenkins et al. in Ref. [1]
between the predictions of anisotropies of the astrophysical gravitational wave
(GW) background, derived using different methods in Cusin et al. [2] and in
Jenkins et al. [3]. We show that this discrepancy is not due to our treatment
of galaxy clustering, contrary to the claim made in Ref. [1] and we show that
our modeling of clustering gives results in very good agreement with
observations. Furthermore we show that the power law spectrum used in Refs. [1]
and [3] to describe galaxy clustering is incorrect on large scales and leads to
a different scaling of the multipoles $C_\ell$. Moreover, we also explain that
the analytic derivation of the gravitational wave background correlation
function in Refs. [1] and [3] is mathematically ill-defined and predicts an
amplitude of the angular power spectrum which depends on the (arbitrary) choice
of a non-physical cut-off.