Ultraviolet properties of Galactic globular clusters with GALEX

TL;DR

This study analyzes ultraviolet colors of 44 Galactic globular clusters using GALEX data, revealing differences based on host galaxy associations and suggesting a correlation between UV color and galaxy mass.

Contribution

First comprehensive UV color analysis of GGCs with GALEX, highlighting differences related to host galaxy type and proposing a new correlation with galaxy mass.

Findings

GGCs associated with Sagittarius dwarf are redder in UV colors.

M31 GCs have similar UV colors to GGCs.

M87 GCs are systematically bluer in UV colors.

Abstract

We present ultraviolet (UV) integrated colors of 44 Galactic globular clusters (GGCs) observed with the Galaxy Evolution Explorer (GALEX) in both FUV and NUV bands. We find for the first time that GCs associated with the Sagittarius dwarf galaxy have (FUV-V) colors systematically redder than GGCs with the same metallicity. M31 GCs show almost the same UV colors as GGCs, while M87 are systematically bluer. We speculate about the presence of an interesting trend, suggesting that the UV color of GCs may be correlated with the mass of the host galaxy, in the sense that more massive galaxies possess bluer clusters.