Dark Matter Profiles in Clusters of Galaxies: a Phenomenological Approach

Abstract

There are some basic differences between the observed properties of galaxies and clusters and the predictions from current hydrodynamical simulations. These are particularly pronounced in the central regions of galaxies and clusters. The popular NFW (Navarro, Frenk, and White) profile, for example, predicts a density cusp at the center, a behavior that (unsurprisingly) has not been observed. While it is not fully clear what are the reasons for this discrepancy, it perhaps reflects (at least partly) insufficient spatial resolution of the simulations. In this paper we explore a purely phenomenological approach to determine dark matter density profiles that are more consistent with observational results. Specifically, we deduce the gas density distribution from measured X-ray brightness profiles, and substitute it in the hydrostatic equilibrium equation in order to derive the form of dark matter profiles. Given some basic theoretical requirements from a dark matter profile, we then consider a number of simple profiles that have the desired asymptotic form. We conclude that a dark matter density profile of the form 1/(1+r/r_a)^3 is most consistent with current observational results.

19 pages, 6 figures. Accepted for publication in New Astronomy

References in corpus (3)

• Dark Halos: The Flattening of the Density Cusp by Dynamical Friction
• Deep inside the core of Abell 1795: the Chandra view
• Chandra Observations of the Lensing Cluster EMSS 1358+6245: Implications for Self-Interacting Dark Matter

Cited by in corpus (5)

• The ESO Nearby Abell Cluster Survey. XII. The mass and mass-to-light-ratio profiles of rich clusters
• The radial profiles of the different mass components in galaxy clusters
• Astrophysical Configurations with Background Cosmology: Probing Dark Energy at Astrophysical Scales
• The polytropic approximation and X-ray scaling relations: constraints on gas and dark matter profiles for galaxy groups and clusters
• A numerical fit of analytical to simulated density profiles in dark matter haloes