Modelling Observational Constraints for Dark Matter Halos

TL;DR

This paper presents a dark matter halo model consistent with observed universal rotation curves and a constant product of central density and core radius, highlighting differences in galaxy and cluster scales.

Contribution

It introduces an observationally motivated dark matter halo model that aligns with galaxy and cluster data, suggesting modifications to standard CDM in inner regions.

Findings

The model fits galaxy rotation curves well.

The product of density and radius is constant in galaxies.

In clusters, this product is about 20 times larger.

Abstract

Observations show that the underlying rotation curves at intermediate radii in spiral and low-surface brightness galaxies are nearly universal. Further, in these same galaxies, the product of the central density and the core radius ($\rho_{0}r_{0}$) is constant. An empirically motivated model for dark matter halos which incorporates these observational constraints is presented and shown to be in accord with the observations. A model fit to the observations of the galaxy cluster Abell 611 shows that $\rho_{0}r_{0}$ for the dark matter halo in this more massive structure is larger by a factor of $\sim 20$ over that assumed for the galaxies. The model maintains the successful NFW form in the outer regions although the well defined differences in the inner regions suggest that modifications to the standard CDM picture are required.