A comparison between the stellar and dynamical masses of six globular clusters

TL;DR

This study compares stellar and dynamical masses of six globular clusters, revealing that stellar masses are generally smaller than dynamical masses, possibly indicating dark remnants or dark matter presence.

Contribution

It provides a detailed comparison of stellar and dynamical masses in globular clusters, accounting for mass segregation, anisotropy, and binaries, highlighting systematic differences.

Findings

Stellar masses are smaller than predicted by standard models.

Stellar masses are about 40% less than dynamical masses.

Possible implications include dark remnants or dark matter in clusters.

Abstract

We present the results of a comprehensive analysis of the structure and kinematics of six Galactic globular clusters. By comparing the results of the most extensive photometric and kinematical surveys available to date with suited dynamical models, we determine the stellar and dynamical masses of these stellar systems taking into account for the effect of mass segregation, anisotropy and unresolved binaries. We show that the stellar masses of these clusters are on average smaller than those predicted by canonical integrated stellar evolution models because of the shallower slope of their mass functions. The derived stellar masses are found to be also systematically smaller than the dynamical masses by ~40%, although the presence of systematics affecting our estimates cannot be excluded. If confirmed, this evidence can be linked to an increased fraction of retained dark remnants or to the presence of a modest amount of dark matter.