The integrated 3point correlation function of cosmic shear
Abstract
We present the integrated 3point shear correlation function $i\zeta_{\pm}$  a higherorder statistic of the cosmic shear field  which can be directly estimated in widearea weak lensing surveys without measuring the full 3point shear correlation function, making this a practical and complementary tool to 2point statistics for weak lensing cosmology. We define it as the 1point aperture mass statistic $M_{\mathrm{ap}}$ measured at different locations on the shear field correlated with the corresponding local 2point shear correlation function $\xi_{\pm}$. Building upon existing work on the integrated bispectrum of the weak lensing convergence field, we present a theoretical framework for computing the integrated 3point function in real space for any projected field within the flatsky approximation and apply it to cosmic shear. Using analytical formulae for the nonlinear matter power spectrum and bispectrum, we model $i\zeta_{\pm}$ and validate it on Nbody simulations within the uncertainties expected from the sixth year cosmic shear data of the Dark Energy Survey. We also explore the Fisher information content of $i\zeta_{\pm}$ and perform a joint analysis with $\xi_{\pm}$ for two tomographic source redshift bins with realistic shapenoise to analyse its power in constraining cosmological parameters. We find that the joint analysis of $\xi_{\pm}$ and $i\zeta_{\pm}$ has the potential to considerably improve parameter constraints from $\xi_{\pm}$ alone, and can be particularly useful in improving the figure of merit of the dynamical dark energy equation of state parameters from cosmic shear data.
 Publication:

arXiv eprints
 Pub Date:
 February 2021
 arXiv:
 arXiv:2102.10177
 Bibcode:
 2021arXiv210210177H
 Keywords:

 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 18 pages + appendix