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

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  • 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.


  • 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