The Globular Cluster Luminosity Function and Specific Frequency in Dwarf Elliptical Galaxies

TL;DR

This study analyzes the properties of globular clusters in dwarf elliptical galaxies, revealing their luminosity functions, specific frequencies, and differences between nucleated and non-nucleated types, with implications for galaxy formation.

Contribution

It provides a comprehensive analysis of globular cluster properties in dwarf ellipticals using HST data, highlighting differences based on galaxy nucleation and environment.

Findings

GCLFs are well-represented by a t_5 function with a peak at -7.3 mag.

S_N and T_MP increase as host galaxy luminosity decreases.

Nucleated dwarf ellipticals have higher T_MP than non-nucleated ones.

Abstract

The globular cluster luminosity function, specific globular cluster frequency, S_N, specific globular cluster mass, T_MP, and globular cluster mass fraction in dwarf elliptical galaxies are explored using the full 69 galaxy sample of the HST WFPC2 Dwarf Elliptical Galaxy Snapshot Survey. The GCLFs of the dEs are well-represented with a t_5 function with a peak at M_{V,Z}^0(dE,HST) = -7.3 +/- 0.1. This is ~0.3 magnitudes fainter than the GCLF peaks in giant spiral and elliptical galaxies, but the results are consistent within the uncertainties. The bright-end slope of the luminosity distribution has a power-law form with slope alpha = -1.9 +/- 0.1. The trend of increasing S_N or T_MP with decreasing host galaxy luminosity is confirmed. The mean value for T_MP in dE,N galaxies is about a factor of two higher than the mean value for non-nucleated galaxies and the distributions of T_MP in dE,N and dE,noN galaxies are statistically different. These data are combined with results from the literature for a wide range of galaxy types and environments. At low host galaxy masses the distribution of T_MP for dE,noN and dI galaxies are similar. This supports the idea that one pathway for forming dE,noN galaxies is by the stripping of dIs. The formation of nuclei and the larger values of T_MP in dE,N galaxies may be due to higher star formation rates and star cluster formation efficiencies due to interactions in galaxy cluster environments.