http://arxiv.org/abs/2004.01666
The significant increase in precision that will be achieved by Stage IV cosmic shear surveys means that several currently used theoretical approximations may cease to be valid. An additional layer of complexity arises from the fact that many of these approximations are interdependent; the procedure to correct for one involves making another. Two such approximations that must be relaxed for upcoming experiments are the reduced shear approximation and the effect of neglecting magnification bias. Accomplishing this involves the calculation of the convergence bispectrum; typically subject to the Limber approximation. In this work, we compute the post-Limber convergence bispectrum, and the post-Limber reduced shear and magnification bias corrections to the angular power spectrum for a Euclid-like survey. We find that the Limber approximation significantly overestimates the bispectrum when any side of the bispectrum triangle, $\ell_i<60$. However, the resulting changes in the reduced shear and magnification bias corrections are well below the sample variance for $\ell\leq5000$.
A. Deshpande and T. Kitching
Mon, 6 Apr 20
36/46
Comments: 10 pages, 4 figures. Submitted to Phys. Rev. D