PostLimber weak lensing bispectrum, reduced shear correction, and magnification bias correction
Abstract
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 postLimber convergence bispectrum, and the postLimber reduced shear and magnification bias corrections to the angular power spectrum for a Euclidlike survey. We find that the Limber approximation significantly overestimates the bispectrum when any side of the bispectrum triangle, ℓ_{i}<60 . However, the resulting changes in the reduced shear and magnification bias corrections are well below the sample variance for ℓ≤5000 . We also compute a worstcase scenario for the additional biases on w_{0}w_{a}CDM cosmological parameters that result from the difference between the postLimber and Limber approximated forms of the corrections. These further demonstrate that the reduced shear and magnification bias corrections can safely be treated under the Limber approximation for upcoming surveys.
 Publication:

Physical Review D
 Pub Date:
 May 2020
 DOI:
 10.1103/PhysRevD.101.103531
 arXiv:
 arXiv:2004.01666
 Bibcode:
 2020PhRvD.101j3531D
 Keywords:

 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 12 pages, 4 figures. Accepted by Phys. Rev. D. Matches published version