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Cold collapse and the core catastrophe (1999)
| Citations: | 28 - 0 self |
BibTeX
@MISC{Moore99coldcollapse,
author = {B. Moore and T. Quinn and F. Governato and J. Stadel and G. Lake},
title = {Cold collapse and the core catastrophe},
year = {1999}
}
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Abstract
We show that a universe dominated by cold dark matter fails to reproduce the rotation curves of dark matter dominated galaxies, one of the key problems that it was designed to resolve. We perform numerical simulations of the formation of dark matter halos, each containing ∼>10 6 particles and resolved to 0.003 times the virial radius, allowing an accurate comparison with rotation curve data. A good fit to both galactic and cluster sized halos can be achieved using the density profile ρ(r) ∝ [(r/rs) 1.5 (1 + (r/rs) 1.5)] −1, where rs is a scale radius. This profile has a steeper asymptotic slope, ρ(r) ∝ r −1.5, and a sharper turnover than found by lower resolution studies. The central structure of relaxed halos that form within a hierarchical universe has a remarkably small scatter (unrelaxed halos would not host disks). We compare the results with a sample of dark matter dominated, low surface brightness (LSB) galaxies with circular velocities in the range 100 − 300 km s −1. The rotation curves of disks within cold dark matter halos rise too steeply to match these data which require a constant mass density in the central regions. The same conclusion is reached if we compare the scale free shape of observed rotation curves with the simulation data. It is important to confirm these results using stellar rather than HI rotation curves for LSB galaxies. We test the effects of introducing a cut-off in the power spectrum that may occur in a universe dominated by warm dark matter. In this case halos form by a monolithic collapse but the final density profile hardly changes, demonstrating that the merger history does not play a role in determining the halo structure. Subject headings: dark matter, galaxies: haloes, formation, kinematics and dynamics – 2 –
Keyphrases
cold collapse dark matter core catastrophe rotation curve resolution study key problem density profile circular velocity low surface brightness scale free shape merger history hi rotation curve warm dark matter unrelaxed halo simulation data accurate comparison virial radius subject heading rotation curve data lsb galaxy steeper asymptotic slope hierarchical universe constant mass density cold dark matter halo final density profile central region cold dark matter observed rotation curve monolithic collapse dark matter halo small scatter scale radius power spectrum numerical simulation central structure relaxed halo halo structure good fit
