Cosmology and the bispectrum

Emiliano Sefusatti, Martín Crocce, Sebastián Pueblas, Román Scoccimarro

    Research output: Contribution to journalArticle

    Abstract

    The present spatial distribution of galaxies in the Universe is non-Gaussian, with 40% skewness in 50h-1Mpc spheres, and remarkably little is known about the information encoded in it about cosmological parameters beyond the power spectrum. In this work we present an attempt to bridge this gap by studying the bispectrum, paying particular attention to a joint analysis with the power spectrum and their combination with CMB data. We address the covariance properties of the power spectrum and bispectrum including the effects of beat coupling that lead to interesting cross-correlations, and discuss how baryon acoustic oscillations break degeneracies. We show that the bispectrum has significant information on cosmological parameters well beyond its power in constraining galaxy bias, and when combined with the power spectrum is more complementary than combining power spectra of different samples of galaxies, since non-Gaussianity provides a somewhat different direction in parameter space. In the framework of flat cosmological models we show that most of the improvement of adding bispectrum information corresponds to parameters related to the amplitude and effective spectral index of perturbations, which can be improved by almost a factor of 2. Moreover, we demonstrate that the expected statistical uncertainties in σ8 of a few percent are robust to relaxing the dark energy beyond a cosmological constant.

    Original languageEnglish (US)
    Article number023522
    JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
    Volume74
    Issue number2
    DOIs
    StatePublished - 2006

    Fingerprint

    Bispectrum
    Cosmology
    Power Spectrum
    cosmology
    power spectra
    Galaxies
    galaxies
    skewness
    Cosmological Models
    Dark Energy
    Beat
    Skewness
    Cosmological Constant
    Baryon
    Cross-correlation
    dark energy
    Spatial Distribution
    cross correlation
    Percent
    Parameter Space

    ASJC Scopus subject areas

    • Physics and Astronomy(all)
    • Nuclear and High Energy Physics
    • Mathematical Physics

    Cite this

    Cosmology and the bispectrum. / Sefusatti, Emiliano; Crocce, Martín; Pueblas, Sebastián; Scoccimarro, Román.

    In: Physical Review D - Particles, Fields, Gravitation and Cosmology, Vol. 74, No. 2, 023522, 2006.

    Research output: Contribution to journalArticle

    Sefusatti, Emiliano ; Crocce, Martín ; Pueblas, Sebastián ; Scoccimarro, Román. / Cosmology and the bispectrum. In: Physical Review D - Particles, Fields, Gravitation and Cosmology. 2006 ; Vol. 74, No. 2.
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