Power spectrum multipoles on the curved sky: an application to the
  6-degree Field Galaxy Survey
  The peculiar velocities of galaxies cause their redshift-space clustering to
depend on the angle to the line-of-sight, providing a key test of gravitational
physics on cosmological scales. These effects may be described using a
multipole expansion of the clustering measurements. Focussing on Fourier-space
statistics, we present a new analysis of the effect of the survey window
function, and the variation of the line-of-sight across a survey, on the
modelling of power spectrum multipoles. We determine the joint covariance of
the Fourier-space multipoles in a Gaussian approximation, and indicate how
these techniques may be extended to studies of overlapping galaxy populations
via multipole cross-power spectra. We apply our methodology to one of the
widest-area galaxy redshift surveys currently available, the 6-degree Field
Galaxy Survey, deducing a normalized growth rate f*sigma_8(z=0.06) = 0.38 +/-
0.12 in the low-redshift Universe, in agreement with previous analyses of this
dataset using different techniques. Our framework should be useful for
processing future wide-angle galaxy redshift surveys.
