The globular cluster system of the Auriga simulations

Timo L. R. Halbesma, Robert J. J. Grand, Facundo A. Gómez, Federico Marinacci, Rüdiger Pakmor, Wilma H. Trick, Philipp Busch, Simon D. M. White

Published 2019-09-05Version 1

We investigate whether the galaxy and star formation model used for the Auriga simulations can produce a realistic GC population. We compare statistics of GC candidate star particles in the Auriga haloes with catalogues of the Milky Way (MW) and Andromeda (M31) GC populations. We find that the Auriga simulations do produce sufficient stellar mass for GC candidates at radii and metallicities that are typical for the MW GC system (GCS). We do observe varying mass-ratios of the simulated GC candidates relative to the observed mass in the MW and M31 GC systems for different bins of galactocentric radius-metallicity (r$_{\text{gal}}$ -[Fe/H]). This may imply that different values for the combined product of the bound cluster formation efficiency and the GC disruption rate are needed. Overall, the Auriga simulations produce GC candidates with higher metallicities than the MW and M31 GCS and they are found at larger radii than observed. Bound cluster formation efficiencies higher than ten percent are needed for the metal-poor GC candidates, and those within the Solar radius should experience negligible destruction rates. GC candidates in the outer halo, on the other hand, should either have low formation efficiencies, or experience high mass loss for the Auriga simulations to produce a GCS that is consistent with that of the MW or M31. Finally, the scatter in the metallicity as well as in the radial distribution between different Auriga runs is considerably smaller than the differences between that of the MW and M31 GCSs. The Auriga model is unlikely to give rise to a GCS that can be consistent with both galaxies.