Stellar Profile Independent Determination of the Dark Matter Distribution of the Fornax Local Group Dwarf Spheroidal Galaxy

TL;DR

This paper introduces a new method to test dark matter halo models against stellar data in dwarf galaxies without assuming a specific stellar profile, revealing insights into Fornax's dark matter distribution.

Contribution

The paper presents a novel, profile-independent approach to compare dark matter models with stellar observations in dwarf galaxies.

Findings

Fornax's dark matter halo is more likely cored than cusped.

Fornax's halo shape shows minor tension with simulations.

No substantial evidence of a stellar disk within Fornax's dark matter halo.

Abstract

The local group dwarf spheroidal galaxies (LG dSphs) are among the most promising astrophysical targets for probing the small scale structure of dark matter (DM) subhalos. We describe a method for testing the correspondence between proposed DM halo models and observations of stellar populations within LG dSphs. By leveraging the gravitational potential of any proposed DM model and the available stellar kinematical data, we can derive a prediction for the observed stellar surface density of an LG dSph that can be directly compared with observations. Because we do not make any reference to an assumed surface brightness profile, our model can be applied to exotic DM distributions that produce atypical stellar density distributions. We use our methodology to determine that the DM halo of the Fornax LG dSph is more likely cored than cusped, ascertain that it is characterized by a semi-minor to semi-major axis ratio in minor tension with simulations, and find no substantial evidence of a disk within the dSph's larger DM halo.