Gravitational collapse in an expanding background and the role of substructure I: Planar collapse

Abstract

We study the interplay of clumping at small scales with the collapse and relaxation of perturbations at much larger scales. We present results of our analysis when the large scale perturbation is modelled as a plane wave. We find that in absence of substructure, collapse leads to formation of a pancake with multi-stream regions. Dynamical relaxation of plane wave is faster in presence of substructure. Scattering of substructures and the resulting enhancement of transverse motions of haloes in the multi-stream region lead to a thinner pancake. In turn, collapse of the plane wave leads to formation of more massive collapsed haloes as compared to the collapse of substructure in absence of the plane wave. The formation of more massive haloes happens without any increase in the total mass in collapsed haloes. A comparison with the Burgers' equation approach in absence of any substructure suggests that the preferred value of effective viscosity depends primarily on the number of streams in a region.

arXiv comment9 pages, 9 figures, uses mn2e.cls. Accepted for publication in the MNRAS

References in corpus (23)

• Stable clustering, the halo model and nonlinear cosmological power spectra
• Large-Scale Structure of the Universe and Cosmological Perturbation Theory
• GADGET: A code for collisionless and gasdynamical cosmological simulations
• Nonlinear evolution of cosmological power spectra
• PINOCCHIO: pinpointing orbit-crossing collapsed hierarchical objects in a linear density field
• Approximation Methods for Non-linear Gravitational Clustering
• Fundamental Discreteness Limitations of Cosmological N-Body Clustering Simulations
• Predicting the number, spatial distribution and merging history of dark matter haloes
• Are Halos of Collisionless Cold Dark Matter Collisionless?
• Scaling properties of the gravitational clustering in the nonlinear regime
• Demonstrating Discreteness and Collision Error in Cosmological N-body Simulations of Dark Matter Gravitational Clustering
• Modelling the Nonlinear Gravitational Clustering in the Expanding Universe
• Nonlinear density evolution from an improved spherical collapse model
• PINOCCHIO and the hierarchical build-up of dark matter haloes
• A Cosmological Kinetic Theory for the Evolution of Cold Dark Matter Halos with Substructure: Quasi-Linear Theory
• Critical Index and Fixed Point in the Transfer of Power in Nonlinear Gravitational Clustering
• Noise-driven evolution in stellar systems: Theory
• Nonlinear evolution of density perturbations using approximate constancy of gravitational potential
• Local Approximations to the Gravitational Collapse of Cold Matter
• Performance Characteristics of TreePM codes
• Self-similar collapse and the structure of dark matter halos: A fluid approach
• Gravitational Instability in Collisionless Cosmological Pancakes
• A Numerical Renormalization Solution for Self-Similar Cosmic Structure Formation

Cited by in corpus (8)

• Effects of the size of cosmological N-Body simulations on physical quantities -- I: Mass Function
• An Improved Semi-Analytical Spherical Collapse Model for Non-linear Density Evolution
• Effects of the size of cosmological N-Body simulations on physical quantities - III: Skewness
• Evolution of the phase-space density and the Jeans scale for dark matter derived from the Vlasov-Einstein equation
• Gravitational collapse in an expanding background and the role of substructure II: Excess power at small scales and its effect of collapse of structures at larger scales
• The Effects of Linear Matter Power Spectrum Enhancement on Dark Matter Substructure
• Effect of small scale density perturbations on the formation of dark matter halo profiles
• On the origin of transient features in cosmological N-Body Simulations