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

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, int , 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 int . GMCs with star formation efficiency smaller than 0.5 are still able to form clusters with large bound fractions.

Can magnetized turbulence set the mass scale of stars?

“…1 of Grudić et al 2019a for a literature compilation of theoretical predictions). For typical local GMCs, these mechanisms (given standard stellar evolution tracks) are more than sufficient to disrupt clouds after a few percent of the total mass is turned into stars (Grudić et al 2016;Kim et al 2018;Li et al 2019). This process must also affect the IMF, as it abruptly cuts off the gas supply for accretion, and could also potentially stir turbulence on small scales.…”

Which feedback mechanisms dominate in the high-pressure environment of the central molecular zone?

“…Krumholz & McKee 2005;Blitz & Rosolowsky 2006;Federrath & Klessen 2012), and the impact of stellar feedback (e.g. Grudić et al 2018;Kim et al 2018;Fujimoto et al 2019;Li et al 2019;Keller et al 2020). This is particularly important, because ISM pressures observed at the peak of the cosmic star formation history are several orders of magnitude higher than those observed in disc galaxies today (e.g.…”

Most stars (and planets?) are born in intense radiation fields

“…It is worth noting that F * ∝ 2 Σcl Mcl, and there is scatter and systematic variation in Σcl and . In observations, numerical simulations, and simple analytic feedback-regulated models (Fall et al 2010;Grudić et al 2018bGrudić et al , 2019Li et al 2019;Wong et al 2019), ∼ (1 + 2000 M pc −2 /Σcl) −1 is generally found ( ∝ Σcl up to a saturation level at ∼ 1), which gives F * ∝ Σ 3 cl Mcl ∝ R 2 cl Σ 4 cl , a highly super-linear dependence. In contrast, the naive assumption that F * ∼ Lcl/R 2 cl (ignoring the fact that star formation is correlated, so assuming stars are uniformly distributed in volume in a cloud) would give F * ∝ Σcl ∝ Σ 2 cl .…”