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The Weak Lensing Bispectrum Induced By Gravity

Munshi, D; Namikawa, T; Kitching, TD; McEwen, JD; Takahashi, R; Bouchet, FR; Taruya, A; (2020) The Weak Lensing Bispectrum Induced By Gravity. Monthly Notices of the Royal Astronomical Society , 493 (3) pp. 3985-3995. 10.1093/mnras/staa296. Green open access

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Recent studies have demonstrated that {\em secondary} non-Gaussianity induced by gravity will be detected with a high signal-to-noise (S/N) by future and even by on-going weak lensing surveys. One way to characterise such non-Gaussianity is through the detection of a non-zero three-point correlation function of the lensing convergence field, or of its harmonic transform, the bispectrum. A recent study analysed the properties of the squeezed configuration of the bispectrum, when two wavenumbers are much larger than the third one. We extend this work by estimating the amplitude of the (reduced) bispectrum in four generic configurations, i.e., {\em squeezed, equilateral, isosceles} and {\em folded}, and for four different source redshifts $z_s=0.5,1.0,1.5,2.0$, by using an ensemble of all-sky high-resolution simulations. We compare these results against theoretical predictions. We find that, while the theoretical expectations based on widely used fitting functions can predict the general trends of the reduced bispectra, a more accurate theoretical modelling will be required to analyse the next generation of all-sky weak lensing surveys. The disagreement is particularly pronounced in the squeezed limit.

Type: Article
Title: The Weak Lensing Bispectrum Induced By Gravity
Open access status: An open access version is available from UCL Discovery
DOI: 10.1093/mnras/staa296
Publisher version: http://dx.doi.org/10.1093/mnras/staa296
Language: English
Additional information: This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: methods: analytical, methods: numerical, methods: statistical
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics
URI: https://discovery.ucl.ac.uk/id/eprint/10092751
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