Relaxation of dark matter halos: how to match observational data?

Abstract

We show that moderate energy relaxation in the formation of dark matter halos invariably leads to profiles that match those observed in the central regions of galaxies. The density profile of the central region is universal and insensitive to either the seed perturbation shape or the details of the relaxation process. The profile has a central core; the multiplication of the central density by the core radius is almost independent of the halo mass, in accordance with observations. In the core area the density distribution behaves as an Einasto profile with low index ($n\sim 0.5$); it has an extensive region with $\rho \propto r^{-2}$ at larger distances. This is exactly the shape that observations suggest for the central region of galaxies. On the other hand, this shape does not fit the galaxy cluster profiles. A possible explanation of this fact is that the relaxation is violent in the case of galaxy clusters; however, it is not violent enough when galaxies or smaller dark matter structures are considered. We discuss the reasons for this.

9 pages, 4 figures, accepted to Astronomy & Astrophysics

References in corpus (5)

• Planck 2013 results. XVI. Cosmological parameters
• The Universal Rotation Curve of Spiral Galaxies. II The Dark Matter Distribution out to the Virial Radius
• NGC 3741: dark halo profile from the most extended rotation curve
• Infall caustics in dark matter halos?
• The real and apparent convergence of N-body simulations of the dark matter structures: is the Navarro-Frenk-White profile real?

Cited by in corpus (5)

• The real and apparent convergence of N-body simulations of the dark matter structures: is the Navarro-Frenk-White profile real?
• Scaling relations for dark matter core density and radius from Chandra X-ray cluster sample
• Cusps in the center of galaxies: a real conflict with observations or a numerical artefact of cosmological simulations?
• A test of invariance of dark matter halo surface density using multiwavelength mock galaxy catalogues
• Can the dark matter annihilation signal be significantly boosted by substructures?