Dark matter distribution and dynamics of dwarf spheroidal galaxies

TL;DR

This paper reviews dynamical models of dwarf spheroidal galaxies to estimate their dark matter content, discussing methods from simple velocity dispersion analysis to complex orbit superposition, and explores formation scenarios through simulations.

Contribution

It provides a comprehensive overview of dynamical modelling techniques for dwarf spheroidals, highlighting recent advances and applications of the Schwarzschild method.

Findings

Mass-anisotropy degeneracy remains a challenge in simple models.

Complex methods can help break degeneracies in dark matter estimates.

Simulations illustrate formation scenarios like tidal stirring and mergers.

Abstract

I review the current status of dynamical modelling of dwarf spheroidal galaxies focusing on estimates of their dark matter content. Starting with the simplest methods using the velocity dispersion profiles I discuss the inherent issues of mass-anisotropy degeneracy and contamination by unbound stars. I then move on to methods of increasing complexity, aiming to break the degeneracy, up to recent applications of the Schwarzschild orbit superposition method. The dynamical modelling is placed in the context of possible scenarios for the formation of dwarf spheroidal galaxies, including the tidal stirring model and mergers of dwarf galaxies. The two scenarios are illustrated with examples from simulations: a comparison between the tidal evolution of dwarfs with cuspy and cored dark matter profiles and the formation of a dwarf spheroidal with prolate rotation.