Cluster Disruption: From infant mortality to long term survival
  How stellar clusters disrupt, and over what timescales, is intimately linked
with how they form. Here, we review the theory and observations of cluster
disruption, both the suggested initial rapid dissolution phase (infant
mortality) and the longer timescale processes that affect clusters after they
emerge from their progenitor GMCs. Over the past decade, the standard paradigm
that has developed is that all/most stars are formed in clusters and that the
vast majority of these groups are disrupted over short timescales (< 10 Myr).
This is thought to be due to the removal of the left over gas from the
star-formation process, known as infant mortality. However, recent results have
suggested that the fraction of stars that form in clusters has been
overestimated, with the majority being formed in unbound groups (i.e.
associations) which expand and disrupt without the need of invoking gas
removal. Dynamical measurements of young massive clusters in the Galaxy suggest
that clusters reach a stable equilibrium at very young (<3 Myr) ages,
suggesting that gas expulsion has little effect on the cluster. After the early
dynamical phase, clusters appear to be long lived and stable objects. We use
the recent WFC3 image of the cluster population in M83 to test empirical
disruption laws and find that the lifetime of clusters strongly depends on
their ambient environment. While the role of cluster mass is less well
constrained (due to the added parameter of the form of the cluster mass
function), we find evidence suggesting that higher mass clusters survive
longer, and that the cluster mass function (at least in M83, outside the
nuclear region) is truncated above ~10^5Msun.
