Exploring the Correlations between Globular Cluster Populations and Supermassive Black Holes in Giant Galaxies

TL;DR

This study investigates the relationship between globular cluster populations and supermassive black hole masses in giant galaxies, revealing that both are correlated with the host galaxy's overall stellar mass.

Contribution

It provides a detailed analysis of the N_GC-M_SMBH relation across different galaxy types and introduces a larger sample to explore correlations with other galaxy properties.

Findings

Elliptical galaxies show the strongest N_GC-M_SMBH correlation.

Total galaxy stellar mass has the tightest correlation with N_GC.

N_GC and M_SMBH are indirectly linked through host galaxy potential.

Abstract

This paper presents an analysis of the correlation between the number of globular clusters (N_GC) in giant galaxies and the mass of the galaxies' central supermassive black hole (M_SMBH). I construct a sample of 20 elliptical, spiral, and S0 galaxies with known SMBH masses and with accurately-measured globular cluster system properties derived from wide-field imaging studies. The coefficients of the best-fitting N_GC-M_SMBH relation for the early-type galaxies are consistent with those from previous work but in some cases have smaller relative errors. I examine the correlation between N_GC and M_SMBH for various subsamples and find that elliptical galaxies show the strongest correlation while S0 and pseudobulge galaxies exhibit increased scatter. I also compare the quality of the fit of the numbers of metal-poor globular clusters versus SMBH mass and the corresponding fit for metal-rich globular clusters. I supplement the 20-galaxy sample with ten additional galaxies with reliable N_GC determinations but without measured M_SMBH. I use this larger sample to investigate correlations between N_GC and host galaxy properties like total galaxy luminosity and stellar mass and bulge luminosity and mass. I find that the tightest correlation is between N_GC and total galaxy stellar mass. This lends support to the notion that N_GC and M_SMBH are not directly linked but are correlated because both quantities depend on the host galaxy potential. Finally, I use the N_GC-M_SMBH relation derived from the 20-galaxy sample to calculate predicted M_SMBH values for the ten galaxies with accurate N_GC measurements but without measured SMBH masses.