Formation of a nuclear star cluster through the inspiral of globular clusters: A case study of the dwarf elliptical galaxy UGC 7346

TL;DR

This study uses N-body simulations to demonstrate that globular cluster inspiral can form nuclear star clusters in dwarf elliptical galaxy UGC 7346 within 1.5 Gyr, matching observed properties.

Contribution

It provides the first detailed simulation-based evidence that globular cluster inspiral can produce NSCs in dwarf galaxies like UGC 7346.

Findings

GC inspiral forms NSC within ~1.5 Gyr

Resulting NSC parameters match observations

More massive GCs produce larger, more massive NSCs

Abstract

Nuclear star clusters (NSCs) are dense stellar environments located in the center of most galaxies. NSCs are thought to form through two primary methods; through the inspiral of globular clusters (GCs) to the galactic center due to dynamical friction, and through in-situ star formation. Recent observations of dwarf elliptical galaxy UGC 7346 suggest that it might be undergoing NSC formation due to the presence of multiple GCs near its photometric center. We perform direct N-body simulations of nine GCs belonging to UGC 7346's GC system to investigate whether their eventual infall to the galactic center would result in the formation of a NSC. Our simulations indicate that GC inspiral leads to the formation of a central stellar over-density relative to the background profile of the host galaxy within $\sim$1.5 Gyr, corresponding to a NSC with a typical mass of $(4.1\text{-}4.5)\times 10^5 M_{\odot}$. Several key structural parameters of the newly formed NSC, including the S\'ersic index, effective radius, and central stellar density, lie well within the range observed for NSCs. We also test a hypothetical scenario in which some of the infalling GCs have larger masses ($M \sim 10^6 M_{\odot}$), resulting in the formation of a more massive NSC whose mass and size are more consistent with observations. Our results suggest that inspiral of GCs is a viable channel for assembling a significant mass in the shape of NSC in the center of dwarf galaxies and that UGC 7346 will host a NSC at its center in about 2-3 Gyr.