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Abstract

We consider an anisotropic search for the stochastic gravitational-wave (GW)
background by decomposing the gravitational-wave sky into its spherical
harmonics components. Previous analyses have used the diffraction limit to
define the highest-order spherical harmonics components used in this search. We
investigate whether the angular resolution of this search is indeed
diffraction-limited by testing our ability to detect and localize simulated GW
signals. We show that while using low-order spherical harmonics modes is
optimal for initially detecting GW sources, the detected sources can be better
localized with higher-order spherical harmonics than expected based on the
diffraction limit argument. Additionally, we discuss how the ability to recover
simulated GW sources is affected by the number of detectors in the network, the
frequency range over which the search is performed, and the method by which the
covariance matrix of the GW skymap is regularized. While we primarily consider
point-source signals in this study, we briefly apply our methodology to
spatially-extended sources and discuss potential future modifications of our
analysis for such signals.