Variations in a Universal Density Profile

TL;DR

This study models dark matter profiles in several dwarf spheroidal galaxies without assuming specific shapes, revealing diverse profiles that generally follow an approximate r^-1 power law with scatter.

Contribution

We introduce a non-parametric, orbit-based modeling technique to derive dark matter profiles in dSph galaxies without shape assumptions, uncovering diverse profiles.

Findings

Dark matter profiles vary significantly among dSphs.

Profiles generally follow an approximate r^-1 power law.

Profiles exhibit considerable scatter around the power law.

Abstract

Using a newly-developed modeling technique, we present orbit-based dynamical models of the Carina, Draco, Fornax, Sculptor, and Sextans dwarf spheroidal (dSph) galaxies. These models calculate the dark matter profiles non-parametrically without requiring any assumptions to be made about their profile shapes. By lifting this restriction we discover a host of dark matter profiles in the dSphs that are different from the typical profiles suggested by both theorists and observers. However, when we scale these profiles appropriately and plot them on a common axis they appear to follow an approximate r^-1 power law with considerable scatter.