Schwarzschild models of the Sculptor dSph galaxy

TL;DR

This paper develops a spherically symmetric Schwarzschild dynamical model for the Sculptor dwarf spheroidal galaxy, constraining its mass distribution and orbital structure, and providing insights into its dark matter content and formation history.

Contribution

It introduces a novel application of Schwarzschild modeling to dwarf spheroidal galaxies, offering detailed constraints on mass and orbital anisotropy.

Findings

Mass within 1 kpc is approximately 8.5×10^7 solar masses.

The galaxy exhibits tangentially biased and slightly isotropic orbital anisotropy.

Cuspy density profiles steeper than NFW are disfavoured.

Abstract

We have developed a spherically symmetric dynamical model of a dwarf spheroidal galaxy using the Schwarzschild method. This type of modelling yields constraints both on the total mass distribution (e.g. enclosed mass and scale radius) as well as on the orbital structure of the system modelled (e.g. velocity anisotropy). Therefore not only can we derive the dark matter content of these systems, but also explore possible formation scenarios. Here we present preliminary results for the Sculptor dSph. We find that the mass of Sculptor within 1kpc is 8.5\times10^(7\pm0.05) M\odot, its anisotropy profile is tangentially biased and slightly more isotropic near the center. For an NFW profile, the preferred concentration (~15) is compatible with cosmological models. Very cuspy density profiles (steeper than NFW) are strongly disfavoured for Sculptor.