TY - JOUR
T1 - Modelling the formation and evolution of star cluster populations in galaxy simulations
AU - Kruijssen, J.M.D.
AU - Pelupessy, F.I.
AU - Lamers, H.J.G.L.M.
AU - Portegies Zwart, S.F.
AU - Icke, V.
PY - 2011
Y1 - 2011
N2 - The formation and evolution of star cluster populations are related to the galactic environment.
Cluster formation is governed by processes acting on galactic scales, and star cluster disruption
is driven by the tidal field. In this paper, we present a self-consistent model for the formation
and evolution of star cluster populations, for which we combine an N-body/smoothed particle
hydrodynamics galaxy evolution code with semi-analytical models for star cluster evolution.
The model includes star formation, feedback, stellar evolution and star cluster disruption by
two-body relaxation and tidal shocks. The model is validated by a comparison to N-body
simulations of dissolving star clusters. We apply the model by simulating a suite of nine
isolated disc galaxies and 24 galaxy mergers. The evolutionary histories of individual clusters
in these simulations are discussed to illustrate how the environment of clusters changes in
time and space. It is found that the variability of the disruption rate with time and space
affects the properties of star cluster populations. In isolated disc galaxies, the mean age of
the clusters increases with galactocentric radius. The combined effect of clusters escaping
their dense formation sites (‘cluster migration’) and the preferential disruption of clusters
residing in dense environments (‘natural selection’) implies that the mean disruption rate of
the population decreases with cluster age. This affects the slope of the cluster age distribution,
which becomes a function of the star formation rate density (star formation rate per unit
volume). The evolutionary histories of clusters in a galaxy merger vary widely and determine
which clusters survive the merger. Clusters that escape into the stellar halo experience low
disruption rates, while clusters orbiting near the starburst region of a merger are disrupted
on short time-scales due to the high gas density. This impacts the age distributions and the
locations of the surviving clusters at all times during a merger. The paper includes a discussion
of potential improvements for the model and a brief exploration of possible applications.
We conclude that accounting for the interplay between the formation, disruption and orbital
histories of clusters enables a more sophisticated interpretation of observed properties of
cluster populations, thereby extending the role of cluster populations as tracers of galaxy
evolution.
AB - The formation and evolution of star cluster populations are related to the galactic environment.
Cluster formation is governed by processes acting on galactic scales, and star cluster disruption
is driven by the tidal field. In this paper, we present a self-consistent model for the formation
and evolution of star cluster populations, for which we combine an N-body/smoothed particle
hydrodynamics galaxy evolution code with semi-analytical models for star cluster evolution.
The model includes star formation, feedback, stellar evolution and star cluster disruption by
two-body relaxation and tidal shocks. The model is validated by a comparison to N-body
simulations of dissolving star clusters. We apply the model by simulating a suite of nine
isolated disc galaxies and 24 galaxy mergers. The evolutionary histories of individual clusters
in these simulations are discussed to illustrate how the environment of clusters changes in
time and space. It is found that the variability of the disruption rate with time and space
affects the properties of star cluster populations. In isolated disc galaxies, the mean age of
the clusters increases with galactocentric radius. The combined effect of clusters escaping
their dense formation sites (‘cluster migration’) and the preferential disruption of clusters
residing in dense environments (‘natural selection’) implies that the mean disruption rate of
the population decreases with cluster age. This affects the slope of the cluster age distribution,
which becomes a function of the star formation rate density (star formation rate per unit
volume). The evolutionary histories of clusters in a galaxy merger vary widely and determine
which clusters survive the merger. Clusters that escape into the stellar halo experience low
disruption rates, while clusters orbiting near the starburst region of a merger are disrupted
on short time-scales due to the high gas density. This impacts the age distributions and the
locations of the surviving clusters at all times during a merger. The paper includes a discussion
of potential improvements for the model and a brief exploration of possible applications.
We conclude that accounting for the interplay between the formation, disruption and orbital
histories of clusters enables a more sophisticated interpretation of observed properties of
cluster populations, thereby extending the role of cluster populations as tracers of galaxy
evolution.
U2 - 10.1111/j.1365-2966.2011.18467.x
DO - 10.1111/j.1365-2966.2011.18467.x
M3 - Article
SN - 0035-8711
VL - 414
SP - 1339
EP - 1364
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 2
ER -