Globular Cluster Systems in Dwarf Galaxies: Catalogs and Comparisons

TL;DR

This study compiles and standardizes data on dwarf galaxies' globular cluster systems to analyze their relation with halo mass, revealing that non-classical dwarfs tend to have higher GC frequencies and deviate from the typical scaling relation.

Contribution

It provides a comprehensive, homogenized dataset for dwarf galaxies' GCS and halo masses, enabling consistent comparison and analysis of the $M_{GCS}-M_h$ relation across different galaxy types.

Findings

Non-classical dwarfs have higher GC specific frequencies.

These dwarfs are systematically offset from the standard $M_{GCS}-M_h$ relation.

Scatter in the relation is driven by ultra diffuse and low-surface brightness galaxies.

Abstract

The connection between a galaxy's total globular cluster system (GCS) mass and its halo mass has been studied for decades and it has been found that galaxies at nearly all observed masses adhere to a linear scaling relation between these properties. However, while we have ample, homogeneous data for galaxies with halo masses $M_h \gtrsim 10^{10} M_{\odot}$ the data available for low-mass galaxies is more sparse, and both GCS mass and halo mass estimates are determined using varying methodologies. This work compiles all available literature data for dwarf galaxies with confident stellar mass and GC count estimates, and converts these estimates to GCS masses and peak halo masses using a standard conversion. This allows for a consistent comparison of these masses to be made and a complete study of the behaviour of the $M_{GCS}-M_h$ relation to be conducted. We compare the positions of classical dwarfs on the scaling relation to that of ultra diffuse galaxies and extremely low-surface brightness galaxies and find that these non-classical dwarfs have, on average, systematically higher GC specific frequencies. This also makes them, on average, systematically positively offset from the $M_{GCS}-M_h$ relation, driving much of the high-$M_{GCS}$ scatter observed.