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

Meghan E. Hughes; Joel L. Pfeffer; Nate Bastian; Marie Martig; J. M. Diederik Kruijssen; Robert A. Crain; Marta Reina-Campos; Sebastian Trujillo-Gomez

doi:10.1093/mnras/stab3597

paper

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

arXiv:2112.02050 · doi:10.1093/mnras/stab3597

Abstract

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 ( $M_{200} = 5.14 \times 1 0^{13} M_{⊙}$ ) 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 above $M_{*} > 1 0^{10} M_{⊙}$ . It is therefore the disruption of high-mass GCs in galaxies with $M_{*} \sim 1 0^{10} M_{⊙}$ 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.

arXiv commentAccepted to MNRAS

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

Abstract

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