Globular Clusters as Tracers of Fine Structure in the Dramatic Shell Galaxy NGC 474 Academic Article

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abstract

• Globular clusters (GCs) are some of the most visible tracers of the merging and accretion history of galaxy halos. Metal-poor GCs, in particular, are thought to arrive in massive galaxies largely through dry, minor merging events, but it is rare to see a direct connection between GCs and visible stellar streams. NGC 474 is a post-merger early-type galaxy with dramatic fine structures made of concentric shells and radial streams that have been more clearly revealed by deep imaging. We present a study of GCs in NGC 474 to better establish the relationship between merger-induced fine structure and the GC system. We find that many GCs are superimposed on visible streams and shells, and about 35% of GCs outside $3R_{\rm e,galaxy}$ are located in regions of fine structure. The spatial correlation between the GCs and fine structure is significant at the 99.9% level, showing that this correlation is not coincidental. The colors of the GCs on the fine structures are mostly blue, and we also find an intermediate-color population that is dominant in the central region, and which will likely passively evolve to have colors consistent with a traditional metal-rich GC population. The association of the blue GCs with fine structures is direct confirmation that many metal-poor GCs are accreted onto massive galaxy halos through merging events, and that progenitors of these mergers are sub-L* galaxies.

authors

• Lim, Sungsoon
• Peng, Eric W
• Duc, Pierre-Alain
• Fensch, Jérémy
• Durrell, Patrick R
• Harris, William Edgar
• Cuillandre, Jean-Charles
• Gwyn, Stephen
• Lançon, Ariane
• Sánchez-Janssen, Rúben

publication date

• February 1, 2017