Multiple-streaming and the Probability Distribution of Density in Redshift Space

Abstract

We examine several aspects of redshift distortions by expressing the redshift-space density in terms of the eigenvalues and orientation of the local Lagrangian deformation tensor. We explore the importance of multiple-streaming using the Zel'dovich approximation (ZA), and compute the average number of streams in real and redshift-space. It is found that multiple-streaming can be significant in redshift-space but negligible in real-space, even at moderate values of the linear fluctuation amplitude ($\sigma <1$). Moreover, unlike their real-space counter-parts, redshift-space multiple-streams can flow past each other with minimal interactions. Such nonlinear redshift-space effects, which operate even when the real-space density field is quite linear, could suppress the classic compression of redshift-structures predicted by linear theory (Kaiser 1987). We also compute using the ZA the probability distribution function (PDF) of density, as well as $S_3$, in real and redshift-space, and compare it with the PDF measured from N-body simulations. The role of caustics in defining the character of the high density tail is examined. It is found that (non-Lagrangian) smoothing, due to both finite resolution or discreteness and small-scale velocity dispersions, is very effective in erasing caustic structures, unless the initial power spectrum is sufficiently truncated.

23 pages, 5 ps figures, submitted to ApJ

References in corpus (4)

• Linear Redshift Distortions: A Review
• Cosmological Perturbations: Entering the Non-Linear Regime
• Modelling the redshift-space distortion of galaxy clustering
• Estimating Omega from Galaxy Redshifts: Linear Flow Distortions and Nonlinear Clustering

Cited by in corpus (16)

• Clustering of Luminous Red Galaxies IV: Baryon Acoustic Peak in the Line-of-Sight Direction and a Direct Measurement of H(z)
• Redshift-Space Distortions, Pairwise Velocities and Nonlinearities
• Probability Distribution Function of Cosmological Density Fluctuations from Gaussian Initial Condition: Comparison of One- and Two-point Log-normal Model Predictions with N-body Simulations
• Perturbation theory and excursion set estimates of the probability distribution function of dark matter, and a method for reconstructing the initial distribution function
• On Modeling and Measuring the Temperature of the z~5 IGM
• Gravitational Clustering from Chi^2 Initial Conditions
• The Real and Redshift Space Density Distribution Function for Large-Scale Structure in the Spherical Collapse Approximation
• Hydrogen Clouds before Reionization: a Lognormal Model Approach
• The origin of 'Great Walls'
• Evolution of the probability distribution function of galaxies in redshift-space
• Ellipsoidal collapse and the redshift space probability distribution function of dark matter
• Is the cosmic UV background fluctuating at redshift z ~ 6 ?
• The maximum extent of the filaments and sheets in the cosmic web: an analysis of the SDSS DR17
• Quantifying the Bull's Eye Effect
• Statistical characteristics of simulated walls
• Isodensity Statistics on Clustering of High-z Objects in Cosmological Redshift-spaces