Determination of the large scale volume weighted halo velocity bias in simulations

Abstract

A profound assumption in peculiar velocity cosmology is $b_v=1$ at sufficiently large scales, where $b_v$ is the volume weighted halo(galaxy) velocity bias with respect to the matter velocity field. However, this fundamental assumption has not been robustly verified in numerical simulations. Furthermore, it is challenged by structure formation theory (BBKS, 1986, ApJ; Desjacques and Sheth, 2010, PRD), which predicts the existence of velocity bias (at least for proto-halos) due to the fact that halos reside in special regions (local density peaks). The major obstacle to measure the volume weighted velocity from N-body simulations is an unphysical sampling artifact. It is entangled in the measured velocity statistics and becomes significant for sparse populations. With recently improved understanding of the sampling artifact (Zhang, Zheng and Jing, 2015, PRD; Zheng, Zhang and Jing, 2015, PRD), for the first time we are able to {\it appropriately correct this sampling artifact and then robustly measure the volume weighted halo velocity bias}. (1) We verify $b_v=1$ within $2\%$ model uncertainty at $k\lesssim 0.1h/$Mpc and $z=0$-$2$ for halos of mass $\sim 10^{12}$-$10^{13}{h}^{-1}{M}_{\odot }$, and, therefore, consolidates a foundation of the peculiar velocity cosmology. (2) We also find statistically significant signs of $b_v\ne 1$ at $k\gtrsim 0.1h/$Mpc. Unfortunately, whether this is real or caused by residual sampling artifact requires further investigation. Nevertheless, cosmology based on $k\gtrsim 0.1h/$Mpc velocity data shall be careful this potential velocity bias.

arXiv comment6 pages, 3 figures. More discussions, main results unchanged. Match the PRD accepted version

References in corpus (20)

• A measurement of the cosmological mass density from clustering in the 2dF Galaxy Redshift Survey
• A test of the nature of cosmic acceleration using galaxy redshift distortions
• A discriminating probe of gravity at cosmological scales
• Observational Tests of Modified Gravity
• Generation of Vorticity and Velocity Dispersion by Orbit Crossing
• The dependence of dark halo clustering on the formation epoch and the concentration parameter
• The nonlinear matter and velocity power spectra in f(R) gravity
• A new method for accurate velocity statistics estimation
• The 6dF Galaxy Velocity Survey: Cosmological constraints from the velocity power spectrum
• Velocity bias in a LCDM model
• Redshift space correlations and scale-dependent stochastic biasing of density peaks
• Baryon acoustic signature in the clustering of density maxima
• Peculiar Velocity Decomposition, Redshift Space Distortion and Velocity Reconstruction in Redshift Surveys. II. Dark Matter Velocity Statistics
• The spatial and velocity bias of linear density peaks and proto-haloes in the Lambda cold dark matter cosmology
• Peculiar Velocity Decomposition, Redshift Space Distortion and Velocity Reconstruction in Redshift Surveys - I. The Methodology
• Large-scale Cosmic Flows from Cosmicflows-2 Catalog
• 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
• On the halo velocity bias

Cited by in corpus (20)

• Large-Scale Galaxy Bias
• Large-scale dark matter simulations
• Cosmological Forecasts for Combined and Next Generation Peculiar Velocity Surveys
• Measuring the growth rate of structure with Type IA Supernovae from LSST
• Evaluating bulk flow estimators for CosmicFlows-4 measurements
• Mapping the real space distributions of galaxies in SDSS DR7: I. Two Point Correlation Functions
• Accurate determination of halo velocity bias in simulations and its cosmological implications
• Impacts of biasing schemes in the one-loop integrated perturbation theory
• Disentangling redshift-space distortions and nonlinear bias using the 2D power spectrum
• The 6x2pt method: supernova velocities meet multiple tracers
• Exploring the Redshift-Space Peculiar Velocity Field and its Power Spectrum
• Kriging Interpolating Cosmic Velocity Field
• Testing General Relativity with the Doppler magnification effect
• Using peculiar velocity surveys to constrain neutrino masses
• Study on the mapping of halo clustering from real space to redshift space
• The Halo Boltzmann Equation
• Quantification of the multi-streaming effect in Redshift Space Distortion
• Halo Profile Evolution and Velocity Bias
• Constraining the optical depth of galaxies and velocity bias with cross-correlation between kinetic Sunyaev-Zeldovich effect and peculiar velocity field
• Breaking the ${\tau }_{\mathrm{T}}-f$ degeneracy of the kinetic Sunyaev Zel'dovich cosmology in redshift space