An Ideal Mass Assignment Scheme for Measuring the Power Spectrum with Fast Fourier Transforms

Cui, Weiguang; Liu, Lei; Yang, Xiaohu; Wang, Yu; Feng, Long-Long; Springel, Volker

doi:10.1086/592079

Cited by 53 publications

(62 citation statements)

References 43 publications

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“…An alternative approach was taken by Cui et al (2008) who introduce the use of Daubechies wavelets to approximate the ideal filter while keeping compactness in position-space. We do not consider this technique here because the centre of mass of the wavelets adopted is offset from the particle position and so they are not well suited for estimation of the density field.…”

Section: Discussionmentioning

confidence: 99%

The VIMOS Public Extragalactic Redshift Survey

Granett

Branchini

Guzzo

et al. 2015

A&A

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Aims. Using the VIMOS Public Extragalactic Redshift Survey (VIPERS) we aim to jointly estimate the key parameters that describe the galaxy density field and its spatial correlations in redshift space. Methods. We use the Bayesian formalism to jointly reconstruct the redshift-space galaxy density field, power spectrum, galaxy bias and galaxy luminosity function given the observations and survey selection function. The high-dimensional posterior distribution is explored using the Wiener filter within a Gibbs sampler. We validate the analysis using simulated catalogues and apply it to VIPERS data taking into consideration the inhomogeneous selection function. Results. We present joint constraints on the anisotropic power spectrum, and the bias and number density of red and blue galaxy classes in luminosity and redshift bins as well as the measurement covariances of these quantities. We find that the inferred galaxy bias and number density parameters are strongly correlated although they are only weakly correlated with the galaxy power spectrum. The power spectrum and redshiftspace distortion parameters are in agreement with previous VIPERS results with the value of the growth rate f σ 8 = 0.38 with 18% uncertainty at redshift 0.7.

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Section: Discussionmentioning

confidence: 99%

The VIMOS Public Extragalactic Redshift Survey

Granett

Branchini

Guzzo

et al. 2015

A&A

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“…As we mentioned above, in underdense regions if the grid is made too fine there will be grid points for which no particle is assigned, which means there is no information on the velocity field, but typically one would set to zero (incorrectly) the velocity. In addition, dividing the interpolated momentum by the interpolated density means that it is difficult to correct for the interpolation kernel after the velocity field is Fourier transformed, unlike the case of the density field (see [45] for a recent discussion of interpolation corrections and comparison of CIC with other mass assignment schemes for the density field). We generate a Gaussian velocity field on a grid of 400 3 cells with a divergence and vorticity power spectra based roughly on expectations from previous measurements in the literature [46] and then interpolate this velocity on the positions of the 640 3 dark matter particles obtained from running an N-body simulation with Gadget2 [47] (see Table I below for more details on the simulations).…”

Section: Testing the Delaunay Methodsmentioning

confidence: 99%

Generation of vorticity and velocity dispersion by orbit crossing

2009

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We study the generation of vorticity and velocity dispersion by orbit crossing using cosmological numerical simulations, and calculate the backreaction of these effects on the evolution of large-scale density and velocity divergence power spectra. We use Delaunay tessellations to define the velocity field, showing that the power spectra of velocity divergence and vorticity measured in this way are unbiased and have better noise properties than for standard interpolation methods that deal with mass weighted velocities. We show that high resolution simulations are required to recover the correct large-scale vorticity power spectrum, while poor resolution can spuriously amplify its amplitude by more than one order of magnitude. We measure the scalar and vector modes of the stress tensor induced by orbit crossing using an adaptive technique, showing that its vector modes lead, when input into the vorticity evolution equation, to the same vorticity power spectrum obtained from the Delaunay method. We incorporate orbit crossing corrections to the evolution of large scale density and velocity fields in perturbation theory by using the measured stress tensor modes. We find that at large scales (k ≃ 0.1 h Mpc −1 ) vector modes have very little effect in the density power spectrum, while scalar modes (velocity dispersion) can induce percent level corrections at z = 0, particularly in the velocity divergence power spectrum. In addition, we show that the velocity power spectrum is smaller than predicted by linear theory until well into the nonlinear regime, with little contribution from virial velocities.

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“…For the power spectrum we used the nonlinear power spectrum from halofit Peacock & Smith (2000) adhering to the L500 cosmological parameters. In addition, to better match the real power spectrum in simulation we added Cloud-In-Cell window function Cui et al (2008) with a 2 h −1 Mpc smoothing kernel in the computation. We tune the free model parameters for weighted and unweighted c 11 respectively to better match the simulation results for the highest mass bin (upper line).…”

Section: Methodsmentioning

confidence: 99%

Halo Intrinsic Alignment: Dependence on Mass, Formation Time, and Environment

Xia

Kang

Wang

et al. 2017

ApJ

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In this paper we use high-resolution cosmological simulations to study halo intrinsic alignment and its dependence on mass, formation time and large-scale environment. In agreement with previous studies using N-body simulations, it is found that massive halos have stronger alignment. For the first time, we find that for given halo mass, older halos have stronger alignment and halos in cluster regions also have stronger alignment than those in filament. To model these dependencies we extend the linear alignment model with inclusion of halo bias and find that the halo alignment with its mass and formation time dependence can be explained by halo bias. However, the model can not account for the environment dependence, as it is found that halo bias is lower in clusters and higher in filaments. Our results suggest that halo bias and environment are independent factors in determining halo alignment. We also study the halo alignment correlation function and find that halos are strongly clustered along their major axes and less clustered along the minor axes. The correlated halo alignment can extend to scale as large as 100h−1 Mpc where its feature is mainly driven by the baryon acoustic oscillation effect.

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An Ideal Mass Assignment Scheme for Measuring the Power Spectrum with Fast Fourier Transforms

Cited by 53 publications

References 43 publications

The VIMOS Public Extragalactic Redshift Survey

The VIMOS Public Extragalactic Redshift Survey

Generation of vorticity and velocity dispersion by orbit crossing

Halo Intrinsic Alignment: Dependence on Mass, Formation Time, and Environment

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