Towards cosmological constraints from the compressed modal bispectrum: A robust comparison of real-space bispectrum estimators
Date Issued
2021
Author(s)
Abstract
Higher-order clustering statistics, like the galaxy bispectrum, can add complementary cosmological information to what is accessible with two-point statistics, like the power spectrum. While the standard way of measuring the bispectrum involves estimating a bispectrum value in a large number of Fourier triangle bins, the compressed modal bispectrum approximates the bispectrum as a linear combination of basis functions and estimates the expansion coefficients on the chosen basis. In this work, we compare the two estimators by using parallel pipelines to analyze the real-space halo bispectrum measured in a suite of N-body simulations corresponding to a total volume of ∼ 1,000 h -3 Gpc3, with covariance matrices estimated from 10,000 mock halo catalogs. We find that the modal bispectrum yields constraints that are consistent and competitive with the standard bispectrum analysis: for the halo bias and shot noise parameters within the tree-level halo bispectrum model up to k max ≈ 0.06 (0.10) h Mpc-1, only 6 (10) modal expansion coefficients are necessary to obtain constraints equivalent to the standard bispectrum estimator using ∼ 20 to 1,600 triangle bins, depending on the bin width. For this work, we have implemented a modal estimator pipeline using Markov Chain Monte Carlo simulations for the first time, and we discuss in detail how the parameter posteriors and modal expansion are robust to, or sensitive to, several user settings within the modal bispectrum pipeline. The combination of the highly efficient compression that is achieved and the large number of mock catalogs available allows us to quantify how our modal bispectrum constraints depend on the number of mocks that are used to estimate covariance matrices and the functional form of the likelihood.
Volume
2021
Issue
3
Start page
105
Issn Identifier
1475-7516
Ads BibCode
2021JCAP...03..105B
Rights
open.access
File(s)![Thumbnail Image]()
![Thumbnail Image]()
Loading...
Name
Byun_2021_JCAP.pdf
Description
[Administrators only]
Size
8.39 MB
Format
Adobe PDF
Checksum (MD5)
a86d4aaa1540104f594e7a987f7195b0
Loading...
Name
2010.09579.pdf
Description
preprint
Size
8.17 MB
Format
Adobe PDF
Checksum (MD5)
635e2ec6ed67ea96a301ac9a2701c6ff