The Coyote Universe I: Precision Determination of the Nonlinear Matter Power Spectrum

Heitmann, Katrin; White, Martin; Wagner, Christian; Habib, Salman; Higdon, David

doi:10.48550/arxiv.0812.1052

Cited by 31 publications

(47 citation statements)

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“…The HaloFit results are approximately 5 − 10% lower than the results from simulations. Heitmann et al (2008) also report a similar disagreement. It appears that the discrepancy in the convergence power at high l is owing to inaccuracy in HaloFit.…”

Section: Power Spectrummentioning

confidence: 78%

Simulations of Wide-Field Weak Lensing Surveys. I. Basic Statistics and Non-Gaussian Effects

Sato¹,

Hamana²,

Takahashi³

et al. 2009

ApJ

193

321

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We study the lensing convergence power spectrum and its covariance for a standard ΛCDM cosmology. We run 400 cosmological N-body simulations and use the outputs to perform a total of 1000 independent ray-tracing simulations. We compare the simulation results with analytic model predictions. The semianalytic model based on Smith et al. fitting formula underestimates the convergence power by ∼ 30% at arcmin angular scales. For the convergence power spectrum covariance, the halo model reproduces the simulation results remarkably well over a wide range of angular scales and source redshifts. The dominant contribution at small angular scales comes from the sample variance due to the number fluctuations of halos in a finite survey volume. The signalto-noise ratio for the convergence power spectrum is degraded by the non-Gaussian covariances by up to a factor of 5 for a weak lensing survey to z s ∼ 1. The probability distribution of the convergence power spectrum estimators, among the realizations, is well approximated by a χ 2 distribution with broadened variance given by the non-Gaussian covariance, but has a larger positive tail. The skewness and kurtosis have non-negligible values especially for a shallow survey. We argue that a prior knowledge on the full distribution may be needed to obtain an unbiased estimate on the ensemble-averaged band power at each angular scale from a finite volume survey.

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Section: Power Spectrummentioning

confidence: 78%

Simulations of Wide-Field Weak Lensing Surveys. I. Basic Statistics and Non-Gaussian Effects

Sato¹,

Hamana²,

Takahashi³

et al. 2009

ApJ

193

321

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“…The nonlinear evolution of the power spectrum in CAMB is calculated using the halofit code (Smith et al 2003). This code is calibrated by n-body simulations and can describe non-linear effects in the shape of the matter power spectrum for pure CDM models to an accuracy of around 5 − 10% (Heitmann et al 2010). However, it has previously been shown that this non-linear model is a poor description of the non-linear effects around the BAO peak (Crocce & Scoccimarro 2008).…”

Section: Non-linear Effectsmentioning

confidence: 99%

The 6dF Galaxy Survey: baryon acoustic oscillations and the local Hubble constant

Beutler¹,

Blake²,

Colless³

et al. 2011

Monthly Notices of the Royal Astronomical Society

2,528

2,354

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We analyse the large‐scale correlation function of the 6dF Galaxy Survey (6dFGS) and detect a baryon acoustic oscillation (BAO) signal at 105 h−1 Mpc. The 6dFGS BAO detection allows us to constrain the distance–redshift relation at zeff= 0.106. We achieve a distance measure of DV(zeff) = 457 ± 27 Mpc and a measurement of the distance ratio, rs(zd)/DV(zeff) = 0.336 ± 0.015 (4.5 per cent precision), where rs(zd) is the sound horizon at the drag epoch zd. The low‐effective redshift of 6dFGS makes it a competitive and independent alternative to Cepheids and low‐z supernovae in constraining the Hubble constant. We find a Hubble constant of H0= 67 ± 3.2 km s−1 Mpc−1 (4.8 per cent precision) that depends only on the Wilkinson Microwave Anisotropy Probe‐7 (WMAP‐7) calibration of the sound horizon and on the galaxy clustering in 6dFGS. Compared to earlier BAO studies at higher redshift, our analysis is less dependent on other cosmological parameters. The sensitivity to H0 can be used to break the degeneracy between the dark energy equation of state parameter w and H0 in the cosmic microwave background data. We determine that w=−0.97 ± 0.13, using only WMAP‐7 and BAO data from both 6dFGS and Percival et al. (2010). We also discuss predictions for the large‐scale correlation function of two future wide‐angle surveys: the Wide field ASKAP L‐band Legacy All‐sky Blind surveY (WALLABY) blind H i survey (with the Australian Square Kilometre Array Pathfinder, ASKAP) and the proposed Transforming Astronomical Imaging surveys through Polychromatic Analysis of Nebulae (TAIPAN) all‐southern‐sky optical galaxy survey with the UK Schmidt Telescope. We find that both surveys are very likely to yield detections of the BAO peak, making WALLABY the first radio galaxy survey to do so. We also predict that TAIPAN has the potential to constrain the Hubble constant with 3 per cent precision.

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“…Our work builds on a long history of studies in non-linear perturbation theory [23,24,25,26,27,28,29,30,31,2], numerical simulations [32,33,34,35], and effective field theory [5,6,8,37]. Related ideas have appeared recently in Refs.…”

Section: The Effective Theorymentioning

confidence: 99%

“…where the integral is over modes with q > Λ. This information is available through the halo model [55] or N -body simulations [33,34,35]. Alternatively, the cosmic energy equation (4.46) relates κ and ω given some initial conditions [32].…”

Section: The Effective Fluidmentioning

confidence: 99%

Cosmological non-linearities as an effective fluid

Baumann

Nicolis

Senatore

et al. 2012

J. Cosmol. Astropart. Phys.

611

1,059

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The universe is smooth on large scales but very inhomogeneous on small scales. Why is the spacetime on large scales modeled to a good approximation by the Friedmann equations? Are we sure that small-scale non-linearities do not induce a large backreaction? Related to this, what is the effective theory that describes the universe on large scales? In this paper we make progress in addressing these questions. We show that the effective theory for the long-wavelength universe behaves as a viscous fluid coupled to gravity: integrating out short-wavelength perturbations renormalizes the homogeneous background and introduces dissipative dynamics into the evolution of long-wavelength perturbations. The effective fluid has small perturbations and is characterized by a few parameters like an equation of state, a sound speed and a viscosity parameter. These parameters can be matched to numerical simulations or fitted from observations. We find that the backreaction of small-scale non-linearities is very small, being suppressed by the large hierarchy between the scale of non-linearities and the horizon scale. The effective pressure of the fluid is always positive and much too small to significantly affect the background evolution. Moreover, we prove that virialized scales decouple completely from the large-scale dynamics, at all orders in the post-Newtonian expansion. We propose that our effective theory be used to formulate a well-defined and controlled alternative to conventional perturbation theory, and we discuss possible observational applications. Finally, our way of reformulating results in second-order perturbation theory in terms of a long-wavelength effective fluid provides the opportunity to understand non-linear effects in a simple and physically intuitive way.

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The Coyote Universe I: Precision Determination of the Nonlinear Matter Power Spectrum

Cited by 31 publications

References 0 publications

Simulations of Wide-Field Weak Lensing Surveys. I. Basic Statistics and Non-Gaussian Effects

Simulations of Wide-Field Weak Lensing Surveys. I. Basic Statistics and Non-Gaussian Effects

The 6dF Galaxy Survey: baryon acoustic oscillations and the local Hubble constant

Cosmological non-linearities as an effective fluid

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