Super-sample tidal modes on the celestial sphere
  The super-sample tidal effect carries information on long-wavelength
fluctuations that we cannot measure directly. It arises from the mode-coupling
between short-wavelength and long-wavelength perturbations beyond a finite
region of a galaxy survey and violates statistical isotropy of observed galaxy
power spectra. In this paper, we propose the use of bipolar spherical harmonic
(BipoSH) decomposition formalism to characterize statistically anisotropic
power spectra. Using the BipoSH formalism, we perform a comprehensive study of
the effect of the super-sample tides on measurements of other cosmological
distortions such as the redshift-space distortion (RSD) and
Alcock-Paczy\'{n}ski (AP) effects by means of the Fisher information matrix
formalism. We find that the BipoSH formalism can break parameter degeneracies
among the super-sample tidal, RSD and AP effects, indicating that the
super-sample tides have little impact on the measurements of the RSD and AP
effects. We also show that the super-sample tides are detectable with an
accuracy better than the $\Lambda$CDM prediction without impairing the accuracy
of measurements of other anisotropies assuming a SPHEREx-like galaxy survey.
