A semi-analytic model of pairwise velocity distribution between dark matter halos

Abstract

We study the probability distribution function (PDF) of relative velocity between two different dark matter halos (i.e. pairwise velocity) with a set of high-resolution cosmological $N$-body simulations. We investigate the pairwise velocity PDFs over a wide range of halo masses of $10^{12.5-15}{h}^{-1}{M}_{\odot }$ and redshifts of $0<z<1$. At a given set of masses, redshift and the separation length between two halos, our model requires three parameters to set the pairwise velocity PDF, whereas previous non-Gaussian models in the literature assume four or more free parameters. At the length scales of $r=5-40[h^{-1}\mathrm{Mpc}]$, our model predicts the mean and dispersion of the pairwise velocity for dark matter halos with their masses of $10^{12.5-13.5}[h^{-1}{M}_{\odot }]$ at $0.3<z<1$ with a 5%-level precision, while the model precision reaches a 20% level (mostly a 10% level) for other masses and redshifts explored in the simulations. We demonstrate that our model of the pairwise velocity PDF provides an accurate mapping of the two-point clustering of massive-galaxy-sized halos at the scales of $O(10)h^{-1}\mathrm{Mpc}$ between redshift and real space for a given real-space correlation function. For a mass-limited halo sample with their masses greater than $10^{13.5}{h}^{-1}{M}_{\odot }$ at $z=0.55$, our model can explain the monopole and quadropole moments of the redshift-space two-point correlations with a precision better than 5% at the scales of $5-40$ and $10-30h^{-1}\mathrm{Mpc}$, respectively. Our model of the pairwise velocity PDF will give a detailed explanation of statistics of massive galaxies at the intermediate scales in redshift surveys, including the non-linear redshift-space distortion effect in two-point correlation functions and the measurements of the kinematic Sunyaev-Zel'dovich effect.

29 pages, 16 figures, 2 tables, Accepted for publication in ApJ

References in corpus (17)

• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Interpretation
• Transients from Initial Conditions in Cosmological Simulations
• Galaxy Evolution from Halo Occupation Distribution Modeling of DEEP2 and SDSS Galaxy Clustering
• A universal model for halo concentrations
• Halo assembly bias and its effects on galaxy clustering
• Observational Tests of Modified Gravity
• A 2.5% measurement of the growth rate from small-scale redshift space clustering of SDSS-III CMASS galaxies
• The Weak Lensing Signal and the Clustering of BOSS Galaxies II: Astrophysical and Cosmological Constraints
• Cosmic Calibration: Constraints from the Matter Power Spectrum and the Cosmic Microwave Background
• Velocity Bias from the Small Scale Clustering of SDSS-III BOSS Galaxies
• Redshift-Space Distortions with the Halo Occupation Distribution II: Analytic Model
• Limitations to the "basic'' HOD model and beyond
• Detection of the pairwise kinematic Sunyaev-Zel'dovich effect with BOSS DR11 and the Atacama Cosmology Telescope
• The Redshift-Space Cluster-Galaxy Cross-Correlation Function: I. Modeling Galaxy Infall onto Millennium Simulation Clusters and SDSS Groups
• Towards a non-Gaussian model of redshift space distortions
• New fitting formula for cosmic non-linear density distribution
• Ellipsoidal collapse and the redshift space probability distribution function of dark matter

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• Galaxy Velocity Bias in Cosmological Simulations: Towards Percent-level Calibration
• Information content in mean pairwise velocity and mean relative velocity between pairs in a triplet