Redshift-space distortions, pairwise velocities, and nonlinearities

Román Scoccimarro

    Research output: Contribution to journalArticle

    Abstract

    We derive the exact relationship, including all nonlinearities, between real-space and redshift-space two-point statistics through the pairwise velocity distribution function. We show using numerical simulations that the pairwise velocity probability distribution function is strongly non-Gaussian at all scales and explain why this is so. We caution that a commonly used ansatz to model the redshift-space power spectrum gives rise to an unphysical distribution of pairwise velocities, and show that it is in general impossible to derive the distribution from measurements of redshift-space clustering. Methods that claim to do this obtain instead something else, whose properties we derive. We provide a general derivation of the large-scale limit of the redshift-space power spectrum and show that it differs from the Kaiser formula by terms that depend on Gaussian and non-Gaussian contributions to the velocity dispersion of large-scale flows. We also show that the large-scale evolution of velocity fields is not well described by linear theory and discuss how this impacts the redshift-space power spectrum. Finally, we stress that using the monopole of the redshift-space power as an indicator of the real-space power spectrum shape can lead to systematic effects in the determination of cosmological parameters; nevertheless a simple procedure is able to recover the large-scale real-space power spectrum rather well.

    Original languageEnglish (US)
    Article number083007
    JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
    Volume70
    Issue number8
    DOIs
    StatePublished - 2004

    Fingerprint

    Pairwise
    nonlinearity
    Nonlinearity
    Power Spectrum
    power spectra
    Velocity Distribution
    velocity distribution
    probability distribution functions
    Probability Distribution Function
    Monopole
    monopoles
    Velocity Field
    Distribution Function
    derivation
    distribution functions
    statistics
    Clustering
    Statistics
    Numerical Simulation
    Term

    ASJC Scopus subject areas

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

    Cite this

    Redshift-space distortions, pairwise velocities, and nonlinearities. / Scoccimarro, Román.

    In: Physical Review D - Particles, Fields, Gravitation and Cosmology, Vol. 70, No. 8, 083007, 2004.

    Research output: Contribution to journalArticle

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