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Baryon Acoustic Oscillations in 2D: Modeling Redshift-space Power Spectrum from Perturbation Theory (1006.0699v1)

Published 3 Jun 2010 in astro-ph.CO and gr-qc

Abstract: We present an improved prescription for matter power spectrum in redshift space taking a proper account of both the non-linear gravitational clustering and redshift distortion, which are of particular importance for accurately modeling baryon acoustic oscillations (BAOs). Contrary to the models of redshift distortion phenomenologically introduced but frequently used in the literature, the new model includes the corrections arising from the non-linear coupling between the density and velocity fields associated with two competitive effects of redshift distortion, i.e., Kaiser and Finger-of-God effects. Based on the improved treatment of perturbation theory for gravitational clustering, we compare our model predictions with monopole and quadrupole power spectra of N-body simulations, and an excellent agreement is achieved over the scales of BAOs. Potential impacts on constraining dark energy and modified gravity from the redshift-space power spectrum are also investigated based on the Fisher-matrix formalism. We find that the existing phenomenological models of redshift distortion produce a systematic error on measurements of the angular diameter distance and Hubble parameter by 1~2%, and the growth rate parameter by ~5%, which would become non-negligible for future galaxy surveys. Correctly modeling redshift distortion is thus essential, and the new prescription of redshift-space power spectrum including the non-linear corrections can be used as an accurate theoretical template for anisotropic BAOs.

Citations (303)

Summary

  • The paper presents an advanced model for the redshift-space power spectrum using perturbation theory to accurately capture non-linear effects relevant to Baryon Acoustic Oscillations (BAOs).
  • The model explicitly accounts for non-linear density-velocity coupling, improving upon traditional linear models and aligning well with N-body simulations on BAO scales.
  • Accurate modeling of redshift space distortions is crucial for precise cosmological parameter measurements from future surveys, potentially avoiding systematic errors from less sophisticated models.

Baryon Acoustic Oscillations in 2D: Modeling Redshift-space Power Spectrum from Perturbation Theory

The paper authored by Taruya, Nishimichi, and Saito presents an advanced model for the matter power spectrum in redshift space. This development is instrumental in accurately capturing the effects pertinent to baryon acoustic oscillations (BAOs) through a nuanced treatment of non-linear gravitational clustering and redshift-space distortion. Unlike several existing models that phenomenologically approximate redshift distortions, this paper provides a theoretical framework that considers the non-linear coupling between density and velocity fields.

Key to the paper is the accurate treatment of redshift distortion effects: the Kaiser effect comprising coherent large-scale flows enhancing power, and the Finger-of-God effect which dampens power due to virialized velocities. The authors employ perturbation theory, explicitly accounting for the non-linear mode coupling, and reconcile their model with N-body simulations by focusing on the monopole and quadrupole power spectra. Their model successfully aligns with simulation data over the critical scales of the BAOs.

From a methodological standpoint, the paper introduces corrections to the redshift distortion model derived from non-linear density-velocity coupling, improving upon the traditional linear or phenomenological models. These corrections lead to a more reliable prediction of angular diameter distance and Hubble parameter measurements. Not surprisingly, this improvement is critical given that existing models potentially induce systematic errors ranging from 1-2% for cosmological parameters derived from BAOs, potentially jeopardizing the precision of future cosmic surveys.

The implications extend to cosmological tests, where the accurate model of redshift space distortions can elucidate the properties of dark energy and alternative gravitational theories. Realizing this, the authors leverage the Fisher matrix formalism to demonstrate the impact on parameter constraints and highlight the risks of neglecting non-linear redshift distortions, thereby stressing the importance of their developed model for upcoming galaxy surveys.

Additionally, future perspectives within the domain are significantly influenced, as this model predicates precise constraints on dark energy and modified gravity, vital for unraveling the mysteries of cosmic acceleration. Predictive capabilities of the model underscore the paper’s utility as a theoretical template essential for anisotropic BAO analysis in a cosmological context.

In conclusion, this model stands as a comprehensive approach for handling redshift space anisotropies in power spectra, delivering implications that extend into both observational strategies and theoretical considerations within cosmological research.