Constraints on the existence of dark matter haloes by the M81 group and the Hickson compact groups of galaxies

TL;DR

This study investigates the dynamical behavior of galaxy groups considering dark matter haloes, finding that observed compact configurations are unlikely if such haloes exist, based on simulations and statistical analysis.

Contribution

It provides new constraints on dark matter halo existence by analyzing galaxy group dynamics with advanced computational methods and simulations.

Findings

High merger rates suggest unstable configurations.

Long-lived unmerged systems are rare and mostly initially unbound.

Observed compact groups are unlikely if dark matter haloes are present.

Abstract

According to the standard model of cosmology the visible, baryonic matter of galaxies is embedded in dark matter haloes, thus extending the mass and the size of galaxies by one to two orders of magnitude. Taking into account dynamical friction between the dark matter haloes, the nearby located M81 group of galaxies as well as the Hickson compact groups of galaxies are here investigated with regard to their dynamical behaviour. The results of the employment of the Markov Chain Monte Carlo method and the genetic algorithm show statistically substantial merger rates between galaxies, and long living constellations without merging galaxies comprise - apart from very few instances - initially unbound systems only. This result is derived based on three- and four-body calculations for a model of rigid Navarro-Frenk-White profiles for the dark matter haloes, but verified by the comparison to randomly chosen individual solutions for the M81 galaxy group with high-resolution simulations of live self-consistent systems (N-body calculations). In consequence, the observed compact configurations of major galaxies are a very unlikely occurence if dark matter haloes exist.