Towards optimal cosmological parameter recovery from compressed bispectrum statistics

Byun, Joyce, Eggemeier, Alexander, Regan, Donough, Seery, David and Smith, Robert (2017) Towards optimal cosmological parameter recovery from compressed bispectrum statistics. Monthly Notices of the Royal Astronomical Society, 471 (2). pp. 1581-1618. ISSN 0035-8711

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Abstract

Over the next decade, improvements in cosmological parameter constraints will be driven by surveys of large-scale structure in the Universe. The information they contain can be measured by suitably-chosen correlation functions, and the non-linearity of structure formation implies that significant information will be carried by the three-point function or higher correlators. Extracting this information is extremely challenging, requiring accurate modelling and significant computational resources to estimate the covariance matrix describing correlation between different Fourier configurations. We investigate whether it is possible to reduce this matrix without significant loss of information by using a proxy that aggregates the bispectrum over a subset of configurations. Specifically, we study constraints on ΛCDM parameters from a future galaxy survey combining the power spectrum with (a) the integrated bispectrum, (b) the line correlation function and (c) the modal decomposition of the bispectrum. We include a simple estimate for the degradation of the bispectrum with shot noise. Our results demonstrate that the modal bispectrum has comparable performance to the Fourier bispectrum, even using considerably fewer modes than Fourier configurations. The line correlation function has good performance, but is less effective. The integrated bispectrum is comparatively insensitive to the background cosmology. Addition of bispectrum data can improve constraints on bias parameters and σ8 by a factor between 3 and 5 compared to power spectrum measurements alone. For other parameters, improvements of up to ∼ 20% are possible. Finally, we use a range of theoretical models to explore the sophistication required to produce realistic predictions for each proxy.

Item Type: Article
Schools and Departments: School of Mathematical and Physical Sciences > Physics and Astronomy
Research Centres and Groups: Astronomy Centre
Subjects: Q Science > QB Astronomy > QB0980 Cosmogony. Cosmology
Depositing User: David Seery
Date Deposited: 11 Aug 2017 11:53
Last Modified: 15 Aug 2017 14:43
URI: http://sro.sussex.ac.uk/id/eprint/69105

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Project NameSussex Project NumberFunderFunder Ref
Precisions tests of the inflationary scenarioG0918EUROPEAN UNION308082
Astrophysics and Cosmology - Sussex Consolidated GrantG1291STFC-SCIENCE AND TECHNOLOGY FACILITIES COUNCILST/L000652/1