Merging of globular clusters within inner galactic regions. II. The Nuclear Star Cluster formation

TL;DR

This study uses N-body simulations to demonstrate how merging globular clusters in galactic centers can form Nuclear Star Clusters with properties matching observations, supporting early galaxy evolution models.

Contribution

It provides detailed simulation evidence that globular cluster mergers can produce Nuclear Star Clusters consistent with observed profiles.

Findings

Merged clusters resemble observed Nuclear Clusters in density and velocity profiles.

Central density of merger remnants exceeds the sum of progenitors.

Dense initial clusters lead to more concentrated merger remnants.

Abstract

In this paper we present the results of two detailed N-body simulations of the interaction of a sample of four massive globular clusters in the inner region of a triaxial galaxy. A full merging of the clusters takes place, leading to a slowly evolving cluster which is quite similar to observed Nuclear Clusters. Actually, both the density and the velocity dispersion profiles match qualitatively, and quantitatively after scaling, with observed features of many nucleated galaxies. In the case of dense initial clusters, the merger remnant shows a density profile more concentrated than that of the progenitors, with a central density higher than the sum of the central progenitors central densities. These findings support the idea that a massive Nuclear Cluster may have formed in early phases of the mother galaxy evolution and lead to the formation of a nucleus, which, in many galaxies, has indeed a luminosity profile similar to that of an extended King model. A correlation with galactic nuclear activity is suggested.