Kriging interpolating cosmic velocity field. II. Taking anistropies and multistreaming into account

Abstract

Measuring the volume-weighted peculiar velocity statistics from inhomogeneously and sparsely distributed galaxies/halos, by existing velocity assignment methods, suffers from a significant sampling artifact. As an alternative, the Kriging interpolation based on Gaussian processes was introduced and evaluated [Y. Yu, J. Zhang, Y. Jing, and P. Zhang, Phys. Rev. D 92, 083527 (2015)]. Unfortunately, the most straightforward application of Kriging does not perform better than the existing methods in the literature. In this work, we investigate two physically motivated extensions. The first takes into account of the anisotropic velocity correlations. The second introduces the nugget effect, on account of multi-streaming of the velocity field. We find that the performance is indeed improved. For sparsely sampled data [$n_P\lesssim 6\times 10^{-3}(h^{-1}\mathrm{Mpc}{)}^{-3}$] where the sampling artifact is the most severe, the improvement is significant and is two-fold: 1) The scale of reliable measurement of the velocity power spectrum is extended by a factor $\sim 1.6$, and 2) the dependence on the velocity correlation prior is weakened by a factor of $\sim 2$. We conclude that such extensions are desirable for accurate velocity assignment by Kriging.

9 pages, 6 figures, accepted by PRD. Matched publication

References in corpus (12)

• Beyond the Cosmological Standard Model
• Cosmological Tests of Modified Gravity
• A test of the nature of cosmic acceleration using galaxy redshift distortions
• A discriminating probe of gravity at cosmological scales
• Confirmation of general relativity on large scales from weak lensing and galaxy velocities
• Observational Tests of Modified Gravity
• The dependence of dark halo clustering on the formation epoch and the concentration parameter
• Differentiating dark energy and modified gravity with galaxy redshift surveys
• Sampling Artifact in Volume Weighted Velocity Measurement.--- I. Theoretical Modelling
• Sampling Artifact in Volume Weighted Velocity Measurement.--- II. Detection in simulations and comparison with theoretical modelling
• Velocity and mass bias in the distribution of dark matter halos
• Kriging Interpolating Cosmic Velocity Field

Cited by in corpus (5)

• Large-scale dark matter simulations
• Accurate determination of halo velocity bias in simulations and its cosmological implications
• Sensitivity tests of cosmic velocity fields to massive neutrinos
• Lagrangian displacement field estimators in cosmology
• Photometry on Structured Backgrounds: Local Pixelwise Infilling by Regression