Cosmological parameters from weak lensing power spectrum and bispectrum
  tomography: including the non-Gaussian errors
  We re-examine a genuine power of weak lensing bispectrum tomography for
constraining cosmological parameters, when combined with the power spectrum
tomography, based on the Fisher information matrix formalism. To account for
the full information at two- and three-point levels, we include all the power
spectrum and bispectrum information built from all-available combinations of
tomographic redshift bins, multipole bins and different triangle configurations
over a range of angular scales (up to lmax=2000 as our fiducial choice). For
the parameter forecast, we use the halo model approach in Kayo, Takada & Jain
(2013) to model the non-Gaussian error covariances as well as the
cross-covariance between the power spectrum and the bispectrum, including the
halo sample variance or the nonlinear version of beat-coupling. We find that
adding the bispectrum information leads to about 60% improvement in the dark
energy figure-of-merit compared to the lensing power spectrum tomography alone,
for three redshift-bin tomography and a Subaru-type survey probing galaxies at
typical redshift of zs~1. The improvement is equivalent to a 1.6 larger survey
area. Thus our results show that the bispectrum or more generally any
three-point correlation based statistics carries complementary information on
cosmological parameters to the power spectrum. However, the improvement is
modest compared to the previous claim derived using the Gaussian error
assumption, and therefore our results imply less additional information in even
higher-order moments such as the four-point correlation function.
