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The squeezed matter bispectrum covariance with responses
- Source :
- JCAP03(2019)008
- Publication Year :
- 2019
-
Abstract
- We present a calculation of the angle-averaged squeezed matter bispectrum covariance ${\rm Cov}\left(B_{m}(k_1, k_1', s_1), B_{m}(k_2, k_2', s_2)\right)$, $s_i \ll k_i,k_i'$ ($i=1,2$), that uses matter power spectrum responses to describe the coupling of large- to short-scale modes in the nonlinear regime. The covariance is given by a certain configuration of the 6-point function, which we show is dominated by response-type mode-coupling terms in the squeezed bispectrum limit. The terms that are not captured by responses are small, effectively rendering our calculation complete and predictive for linear $s_1,s_2$ values and any nonlinear values of $k_1,k_1',k_2,k_2'$. Our numerical results show that the squeezed bispectrum super-sample covariance is only a negligible contribution. We also compute the power spectrum-bispectrum cross-covariance using responses. Our derivation for the squeezed matter bispectrum is the starting point to calculate analytical covariances for more realistic galaxy clustering and weak-lensing applications. It can also be used in cross-checks of numerical ensemble estimates of the general bispectrum covariance, given that it is effectively noise-free and complete in the squeezed limit.<br />Comment: 29 pages + appendices; 3 figures and 1 table. The busy reader can focus on the summary in the Introduction, Table 1 and Section 6 with results. Comments welcomed. v2: minor corrections to the text; version published on JCAP
- Subjects :
- Astrophysics - Cosmology and Nongalactic Astrophysics
Subjects
Details
- Database :
- arXiv
- Journal :
- JCAP03(2019)008
- Publication Type :
- Report
- Accession number :
- edsarx.1901.01243
- Document Type :
- Working Paper
- Full Text :
- https://doi.org/10.1088/1475-7516/2019/03/008