Disruption of giant molecular clouds and formation of bound star clusters under the influence of momentum stellar feedback

Abstract

Abstract Energetic feedback from star clusters plays a pivotal role in shaping the dynamical evolution of giant molecular clouds (GMCs). To study the effects of stellar feedback on the star formation efficiency of the clouds and the dynamical response of embedded star clusters, we perform a suite of isolated GMC simulations with star formation and momentum feedback subgrid models using the moving-mesh hydrodynamics code Arepo. The properties of our simulated GMCs span a wide range of initial mass, radius, and velocity configurations. We find that the ratio of the final stellar mass to the total cloud mass, ϵint, scales strongly with the initial cloud surface density and momentum feedback strength. This correlation is explained by an analytic model that considers force balancing between gravity and momentum feedback. For all simulated GMCs, the stellar density profiles are systematically steeper than that of the gas at the epochs of the peaks of star formation, suggesting a centrally concentrated stellar distribution. We also find that star clusters are always in a sub-virial state with a virial parameter ∼0.6 prior to gas expulsion. Both the sub-virial dynamical state and steeper stellar density profiles prevent clusters from dispersal during the gas removal phase of their evolution. The final cluster bound fraction is a continuously increasing function of ϵint. GMCs with star formation efficiency smaller than 0.5 are still able to form clusters with large bound fractions.