Evolution of the Dark Matter Phase-Space Density Distributions of LCDM Halos

Abstract

We study the evolution of phase-space density during the hierarchical structure formation of LCDM halos. We compute both a spherically-averaged surrogate for phase-space density (Q) and the coarse-grained distribution function f(x,v) for dark matter particles that lie within~2 virial radii of four Milky-Way-sized dark matter halos. The estimated f(x,v) spans over four decades at any radius. Dark matter particles that end up within two virial radii of a Milky-Way-sized DM halo at $z=0$ have an approximately Gaussian distribution in log(f) at early redshifts, but the distribution becomes increasingly skewed at lower redshifts. The value corresponding to the peak of the Gaussian decreases as the evolution progresses and is well described by a power-law in (1+z). The highest values of f are found at the centers of dark matter halos and subhalos, where f can be an order of magnitude higher than in the center of the main halo. The power-law Q(r) profile likely reflects the distribution of entropy (K = sigma^2/rho^{2/3} \propto r^{1.2}), which dark matter acquires as it is accreted onto a growing halo. The estimated f(x, v), on the other hand, exhibits a more complicated behavior. Although the median coarse-grained phase-space density profile F(r) can be approximated by a power-law in the inner regions of halos and at larger radii the profile flattens significantly. This is because phase-space density averaged on small scales is sensitive to the high-f material associated with surviving subhalos, as well as relatively unmixed material (probably in streams) resulting from disrupted subhalos, which contribute a sizable fraction of matter at large radii. (ABRIDGED)

Closely matches version accepted for publication

References in corpus (9)

• Clumps and streams in the local dark matter distribution
• The virialized mass of dark matter haloes
• The fine-grained phase-space structure of Cold Dark Matter halos
• Fossils of Reionization in the Local Group
• The distribution function of dark matter in massive haloes
• Evolution of Phase-Space Density in Dark Matter Halos
• Entropy of gas and dark matter in galaxy clusters
• Phase-space structures I: A comparison of 6D density estimators
• Phase-Space Density Profiles in Scale-Free Cosmologies

Cited by in corpus (33)

• The Diversity and Similarity of Simulated Cold Dark Matter Halos
• Dark matter response to galaxy formation
• The phase space density of fermionic dark matter haloes
• Fermionic warm dark matter produces galaxy cores in the observed scales because of quantum mechanics
• Model independent analysis of dark matter points to a particle mass at the keV scale
• The Density and Pseudo-Phase-Space Density Profiles of CDM halos
• The mass of the dark matter particle from theory and observations
• The impact of baryon physics on the structure of high-redshift galaxies
• Secondary Infall and the Pseudo-Phase-Space Density Profiles of Cold Dark Matter Halos
• Phase-space structures II: Hierarchical Structure Finder
• Self-Similar Dynamical Relaxation of Dark Matter Halos in an Expanding Universe
• Probing the Astrophysics of Cluster Outskirts
• Non--power law behavior of the radial profile of phase--space density of halos
• Further constraining galaxy evolution models through the Size Function of SDSS Early-type galaxies
• Deep spectroscopy in nearby galaxy clusters: III Orbital structure of galaxies in Abell 85
• Entropy principle and complementary second law of thermodynamics for self-gravitating systems
• Baryonic impact on the dark matter orbital properties of Milky Way-sized haloes
• Structure and History of Dark Matter Halos Probed with Gravitational Lensing
• Supermodel Analysis of Galaxy Clusters
• Constant surface gravity and density profile of dark matter
• Estimating multidimensional probability fields using the Field Estimator for Arbitrary Spaces (FiEstAS) with applications to astrophysics
• Theoretical dark matter halo kinematics and triaxial shape
• Evolution of the phase-space density and the Jeans scale for dark matter derived from the Vlasov-Einstein equation
• Velocity Structure of Self-Similar Spherically Collapsed Halos
• On the Apparent Power Law in CDM Halo Pseudo Phase Space Density Profiles
• The Structure of Cold Dark Matter Halos: Recent Insights from High Resolution Simulations
• A Universal Power-law Profile of Pseudo-Phase-Space Density-like Quantities in Elliptical Galaxies
• Dark Matter Halos: The Dynamical Basis of Effective Empirical Models
• Structural and dynamical modeling of WINGS clusters. III. The pseudo phase-space density profile
• Gamma Rays from Annihilations at the Galactic Center in a Physical Dark Matter Distribution
• Dynamics of merging: Post-merger mixing and relaxation of an Illustris galaxy
• Phase-Space Evolution of Dark Matter Halos
• The Non-universal Pseudo Phase-Space Density Profiles of Symphony Host Halos