The test for suppressed dynamical friction in a constant density core of dwarf galaxies

TL;DR

This paper investigates the mechanism behind the suppression of dynamical friction in dwarf galaxy cores, using N-body simulations to challenge the co-rotating state explanation and clarify why core halos allow GCs to survive.

Contribution

The study provides a new analysis showing that the suppression of dynamical friction is not due to co-rotation, offering a revised understanding of GC dynamics in dwarf galaxy cores.

Findings

Core halos significantly suppress dynamical friction.

The co-rotating state is not the primary mechanism for suppression.

Dwarf galaxy GCs can survive longer than previously expected.

Abstract

The dynamical friction problem is a long-standing dilemma about globular clusters (hereafter,GCs) belonging to dwarf galaxies. GCs are strongly affected by dynamical friction in dwarf galaxies, and are presumed to fall into the galactic center. But, GCs do exist in dwarf galaxies generally. A solution of the problem has been proposed. If dwarf galaxies have a core dark matter halo which has constant density distribution in its center, the effect of dynamical friction will be weakened considerably, and GCs should be able to survive beyond the age of the universe. Then, the solution argued that, in a cored dark halo, the suppression of dynamical friction is caused by a new equilibrium state constructed by the interaction between the halo and the GC, in which a part of the halo rotates along with the GC (co-rotating state). In this study, I tested whether the solution is reasonable and reconsidered why a constant density, core halo suppresses dynamical friction, by means of N-body simulations. As a result, I conclude that the true mechanism of suppressed dynamical friction is not the co-rotating state, although a core halo can actually suppress dynamical friction on GCs significantly.