Modal compression of the redshift-space galaxy bispectrum

Joyce Byun, Elisabeth Krause

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

We extend the modal decomposition method, previously applied to compress the information in the real-space bispectrum to the anisotropic redshift-space galaxy bispectrum. In the modal method approach, the bispectrum is expanded on a basis of smooth functions of triangles and their orientations, such that a set of modal expansion coefficients can capture the information in the bispectrum. We assume a reference survey and compute Fisher forecasts for the compressed modal bispectrum and two other basis decompositions of the redshift-space bispectrum in the literature, one based on (single) spherical harmonics and another based on tripolar spherical harmonics. In each case, we compare the forecasted constraints from the compressed statistic with forecasted constraints from the full uncompressed bispectrum which includes all triangles and orientations. Our main result is that all three compression methods achieve good recovery of the full information content of the bispectrum, but the modal decomposition approach achieves this the most efficiently: only 14 (42) modal expansion coefficients are necessary to obtain constraints that are within 10 (2) per cent of the full bispectrum result. The next most efficient decomposition is the one based on tripolar spherical harmonics, while the spherical harmonic multipoles are the least efficient.

Original languageEnglish (US)
Pages (from-to)4854-4870
Number of pages17
JournalMonthly Notices of the Royal Astronomical Society
Volume525
Issue number4
DOIs
StatePublished - Nov 1 2023

Keywords

  • Cosmology: theory
  • large-scale structure of the Universe

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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