Simulating the Complexity of the Dark Matter Sheet I: Numerical Algorithms

Abstract

At early times dark matter has a thermal velocity dispersion of unknown amplitude which, for warm dark matter models, can influence the formation of nonlinear structure on observable scales. We propose a new scheme to simulate cosmologies with a small-scale suppression of perturbations that combines two previous methods in a way that avoids the numerical artefacts which have so far prevented either from producing fully reliable results. At low densities and throughout most of the cosmological volume, we represent the dark matter phase-sheet directly using high-accuracy interpolation, thereby avoiding the artificial fragmentation which afflicts particle-based methods in this regime. Such phase-sheet methods are, however, unable to follow the rapidly increasing complexity of the denser regions of dark matter haloes, so for these we switch to an N-body scheme which uses the geodesic deviation equation to track phase-sheet properties local to each particle. In addition, we present a novel high-resolution force calculation scheme based on an oct-tree of cubic force resolution elements which is well suited to approximate the force-field of our combined sheet+particle distribution. Our hybrid simulation scheme enables the first reliable simulations of the internal structure of low-mass haloes in a warm dark matter cosmology.

arXiv comment23 pages, 28 figures

References in corpus (23)

• The cosmological simulation code GADGET-2
• Simulating the joint evolution of quasars, galaxies and their large-scale distribution
• How Filaments are Woven into the Cosmic Web
• Halo Formation in Warm Dark Matter Models
• The Inner Structure of LambdaCDM Halos I: A Numerical Convergence Study
• Dark matter and cosmic structure
• An energy-conserving formalism for adaptive gravitational force softening in SPH and N-body codes
• Nonlinear Evolution of Cosmological Structures in Warm Dark Matter Models
• Discreteness effects in simulations of Hot/Warm dark matter
• Tracing the Dark Matter Sheet in Phase Space
• The Warm DM halo mass function below the cut-off scale
• N-body simulations of gravitational dynamics
• The Cosmic Web, Multi-Stream Flows, and Tessellations
• The fine-grained phase-space structure of Cold Dark Matter halos
• ORIGAMI: Delineating Halos using Phase-Space Folds
• Streams and caustics: the fine-grained structure of LCDM haloes
• A new approach to simulating collisionless dark matter fluids
• An adaptively refined phase-space element method for cosmological simulations and collisionless dynamics
• ColDICE: a parallel Vlasov-Poisson solver using moving adaptive simplicial tessellation
• Dark Matter Caustics
• Adaptive gravitational softening in GADGET
• Large-Scale Velocity Dispersion and the Cosmic Web
• The median density of the Universe

Cited by in corpus (24)

• The BACCO Simulation Project: Exploiting the full power of large-scale structure for cosmology
• Large-scale dark matter simulations
• Accurate initial conditions for cosmological N-body simulations: Minimizing truncation and discreteness errors
• Inner cusps of the first dark matter haloes: Formation and survival in a cosmological context
• Phase-space structure of protohalos: Vlasov versus Particle-Mesh
• Measuring the Tidal Response of Structure Formation: Anisotropic Separate Universe Simulations using TreePM
• Cosmological Vlasov-Poisson equations for dark matter: Recent developments and connections to selected plasma problems
• Perturbation theory with dispersion and higher cumulants: framework and linear theory
• Gravitational focusing effects on streaming dark matter as a new detection concept
• Non-Halo Structures and their Effects on Gravitational Lensing
• BullFrog: Multi-step perturbation theory as a time integrator for cosmological simulations
• Primordial dust rings, hidden dust mass, and the first generation of planetesimals in gravitationally unstable protoplanetary disks
• DALI sensitivity to streaming axion dark matter
• Computing the gravitational potential on nested meshes using the convolution method
• Starting Cosmological Simulations from the Big Bang
• Enhanced Small-Scale Structure in the Cosmic Dark Ages
• The cusp-halo relation
• Discreteness effects in $N$-body simulations of warm dark matter
• The Boosted Potential
• Excursion Sets with a "Perfect" Collapse Model
• STRAWBERRY: Finding haloes in the gravitational potential
• Non-halo structures and their effects on gravitationally lensed galaxies
• Simulating the complexity of the dark matter sheet II: halo and subhalo mass functions for non-cold dark matter models
• Tidal adaptive softening and artificial fragmentation in cosmological simulations