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 ($M_{\mathrm{200}} = 5.14 \times 10^{13} M_{\odot}$) 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 above $M_* >
10^{10} M_{\odot}$. It is therefore the disruption of high-mass GCs in galaxies
with $M_{*}\sim 10^{10} M_{\odot}$ 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.
