The Inner Structure of LambdaCDM Halos I: A Numerical Convergence Study
Chris Power,Julio F. Navarro,Adrian Jenkins,Carlos S. Frenk,Simon D. M. White,Volker Springel,Joachim Stadel,T. Quinn +7 more
TLDR
In this article, a comprehensive set of convergence tests are presented to explore the role of various numerical parameters on the equilibrium structure of a simulated dark matter halo, and two independent, state-of-the-art, multi-stepping, parallel N-body codes: PKDGRAV and GADGET.Abstract:
We present a comprehensive set of convergence tests which explore the role of various numerical parameters on the equilibrium structure of a simulated dark matter halo. We report results obtained with two independent, state-of-the-art, multi-stepping, parallel N-body codes: PKDGRAV and GADGET. We find that convergent mass profiles can be obtained for suitable choices of the gravitational softening, timestep, force accuracy, initial redshift, and particle number. For softenings chosen so that particle discreteness effects are negligible, convergence in the circular velocity is obtained at radii where the following conditions are satisfied: (i) the timestep is much shorter than the local orbital timescale; (ii) accelerations do not exceed a characteristic acceleration imprinted by the gravitational softening; and (iii) enough particles are enclosed so that the collisional relaxation timescale is longer than the age of the universe. The most stringent requirement for convergence is typically that imposed on the particle number by the collisional relaxation criterion, which implies that in order to estimate accurate circular velocities at radii where the density contrast may reach $\sim 10^6$, the region must enclose of order 3000 particles (or more than a few times $10^6$ within the virial radius). Applying these criteria to a galaxy-sized $\Lambda$CDM halo, we find that the spherically-averaged density profile becomes progressively shallower from the virial radius inwards, reaching a logarithmic slope shallower than -1.2 at the innermost resolved point, $r \sim 0.005 r_{200}$, with little evidence for convergence to a power-law behaviour in the inner regions.read more
Citations
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The Cosmological simulation code GADGET-2
TL;DR: GADGET-2 as mentioned in this paper is a massively parallel tree-SPH code, capable of following a collisionless fluid with the N-body method, and an ideal gas by means of smoothed particle hydrodynamics.
Journal ArticleDOI
The Aquarius Project: the subhaloes of galactic haloes
Volker Springel,Jie Wang,Mark Vogelsberger,Aaron D. Ludlow,Adrian Jenkins,Amina Helmi,Julio F. Navarro,Julio F. Navarro,Carlos S. Frenk,Simon D. M. White +9 more
TL;DR: In this article, the authors performed the largest ever particle simulation of a Milky Way sized dark matter halo, and presented the most comprehensive convergence study for an individual dark mass halo carried out thus far.
Journal ArticleDOI
The inner structure of ΛCDM haloes – III. Universality and asymptotic slopes
Julio F. Navarro,Eric Hayashi,Chris Power,Adrian Jenkins,Carlos S. Frenk,Simon D. M. White,Volker Springel,Joachim Stadel,Thomas R. Quinn +8 more
TL;DR: In this article, the authors investigate the mass profile of cold dark matter (ΛCDM) haloes using a suite of numerical simulations spanning five decades in halo mass, from dwarf galaxies to rich galaxy clusters.
Journal ArticleDOI
Resolving cosmic structure formation with the Millennium-II simulation
TL;DR: The Millennium-II Simulation (MS-II) as mentioned in this paper is a very large N-body simulation of dark matter evolution in the concordance A cold dark matter (ACDM) cosmology.
Journal ArticleDOI
Dark matter halo concentrations in the Wilkinson Microwave Anisotropy Probe year 5 cosmology
TL;DR: In this paper, a combination of three large N-body simulations was used to investigate the dependence of dark matter halo concentrations on halo mass and redshift in the Wilkinson Microwave Anisotropy Probe year 5 (WMAP5) cosmology.
References
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