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The integrated bispectrum and beyond

Munshi, Dipak and Coles, Peter 2017. The integrated bispectrum and beyond. Journal of Cosmology and Astroparticle Physics 2017 (02) , 010. 10.1088/1475-7516/2017/02/010

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Abstract

The position-dependent power spectrum has been recently proposed as a descriptor of gravitationally induced non-Gaussianity in galaxy clustering, as it is sensitive to the "soft limit" of the bispectrum (i.e. when one of the wave number tends to zero). We generalise this concept to higher order and clarify their relationship to other known statistics such as the skew-spectrum, the kurt-spectra and their real-space counterparts the cumulants correlators. Using the Hierarchical Ansatz (HA) as a toy model for the higher order correlation hierarchy, we show how in the soft limit, polyspectra at a given order can be identified with lower order polyspectra with the same geometrical dependence but with renormalised amplitudes expressed in terms of amplitudes of the original polyspectra. We extend the concept of position-dependent bispectrum to bispectrum of the divergence of the velocity field Θ and mixed multispectra involving δ and Θ in the 3D perturbative regime. To quantify the effects of transients in numerical simulations, we also present results for lowest order in Lagrangian perturbation theory (LPT) or the Zel'dovich approximation (ZA). Finally, we discuss how to extend the position-dependent spectrum concept to encompass cross-spectra. And finally study the application of this concept to two dimensions (2D), for projected galaxy maps, convergence κ maps from weak-lensing surveys or maps of CMB secondaries e.g. the frequency cleaned y-parameter maps of thermal Sunyaev-Zel'dovich (tSZ) effect from CMB surveys.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Physics and Astronomy
Subjects: Q Science > QC Physics
Uncontrolled Keywords: non-gaussianity, power spectrum, redshift surveys
Publisher: IOP Publishing
ISSN: 1475-7516
Funders: STFC
Date of First Compliant Deposit: 31 May 2017
Date of Acceptance: 27 January 2017
Last Modified: 19 Oct 2019 04:07
URI: http://orca-mwe.cf.ac.uk/id/eprint/101023

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