The physics governing the upper truncation mass of the globular cluster mass function

The mass function of globular cluster (GC) populations is a fundamental observable that encodes the physical conditions under which these massive stellar clusters formed and evolved. The high-mass end of star cluster mass functions are commonly described using a Schechter function, with an exponential truncation mass M c,∗. For the GC mass functions in the Virgo galaxy cluster, this truncation mass increases with galaxy mass ( M∗). In this paper, we fit Schechter mass functions to the GCs in the most massive galaxy group ( M 200 = 5 . 14 ×10 13 M ⊙) in the E-MOSAICS simulations. The fiducial cluster formation model in E-MOSAICS reproduces the observed trend of M c,∗with M∗for the Virgo cluster. We therefore examine the origin of the relation by fitting M c,∗as a function of galaxy mass, with and without accounting for mass loss by two-body relaxation, tidal shocks and/or dynamical friction. In the absence of these mass-loss mechanisms, the M c,∗- M∗relation is flat abo v e M∗> 10 10 M ⊙. It is therefore the disruption of high-mass GCs in galaxies with M∗∼10 10 M ⊙that lowers the M c,∗in these galaxies. High-mass GCs are able to survive in more massive galaxies, since there are more mergers to facilitate their redistribution to less-dense environments. The M c,∗-M∗relation is therefore a consequence of both the formation conditions of massive star clusters and their environmentally dependent disruption mechanisms.