The Core-Cusp Problem

TL;DR

The paper investigates the core/cusp problem by contrasting DM core indications in low surface brightness and gas-rich dwarf galaxies with CDM-predicted cuspy profiles. It synthesizes evidence from HI and H$\alpha$ rotation curves and high-resolution velocity fields, showing that observational data increasingly favor core-like DM distributions, though early work left room for systematic biases. It then discusses baryonic processes (feedback, mergers, dynamical friction) and halo triaxiality as potential mechanisms to reconcile observations with cusps, highlighting mixed results and the need for self-consistent simulations that incorporate complex baryon–dark matter interactions. The work emphasizes the ongoing challenge of linking small-scale galaxy dynamics to cosmological DM models, underscoring the importance of high-resolution observations and baryon-inclusive simulations in resolving the core/cusp controversy.

Abstract

This paper gives an overview of the attempts to determine the distribution of dark matter in low surface brightness disk and gas-rich dwarf galaxies, both through observations and computer simulations. Observations seem to indicate an approximately constant dark matter density in the inner parts of galaxies, while cosmological computer simulations indicate a steep power-law-like behaviour. This difference has become known as the "core/cusp problem", and remains one of the unsolved problems in small-scale cosmology.