A forecast for the detection of the power asymmetry from galaxy surveys
  We investigate the possibility of detecting in redshift surveys a
hemispherical power asymmetry similar to that first reported in CMB
observations. We assume the hemispherical asymmetry arises from a linear
gradient in comoving coordinates in the perturbation amplitude. We predict the
resulting clustering of galaxy or galaxy cluster tracers using an excursion set
approach; doing so accounts for the variation of both the underlying clustering
and the tracer bias. Based on the predicted variation of the clustering of
tracers, we perform a Fisher matrix forecast of the galaxy clustering amplitude
and calculate the statistical significance for ideal surveys and planned
surveys. The results indicate that the DESI galaxy survey would be able to
detect this signal with higher than $3\sigma$ significance if the asymmetry
does exist. We also investigate the amplitude and scale dependence of the above
result. The DESI galaxy survey can probe the dipole amplitude higher than 0.04,
which correspond to a $\pm4\%$ difference of the temperature fluctuation along
and opposite the dipole direction, at least at the $2\sigma$ level.
Additionally, we investigate a modulation of the power spectrum that exhibits
asymmetry only for large scales. This modulation is potentially detectable. For
Milky Way galaxy mass tracers, the scale-dependent modulation yields a larger
change in the large scale power spectrum than does a scale-independent
modulation, because the former does not alter the bias.
