Simulating radiative feedback and star cluster formation in GMCs: I. Dependence on gravitational boundedness

TL;DR

This study uses simulations to investigate how initial gravitational boundedness and radiative feedback influence star cluster formation in GMCs, finding that boundedness has a stronger effect than feedback on formation efficiency and cluster properties.

Contribution

It introduces a simulation framework that models early cluster formation in GMCs with varying virial parameters, highlighting the dominant role of gravitational boundedness over radiative feedback.

Findings

Radiative feedback slightly reduces cluster formation efficiency.

Initial virial parameter significantly affects cluster formation and mass distribution.

Star formation rates increase over time, exceeding observational values at late stages.

Abstract

Radiative feedback is an important consequence of cluster formation in Giant Molecular Clouds (GMCs) in which newly formed clusters heat and ionize their surrounding gas. The process of cluster formation, and the role of radiative feedback, has not been fully explored in different GMC environments. We present a suite of simulations which explore how the initial gravitational boundedness, and radiative feedback, affect cluster formation. We model the early evolution ($<$ 5 Myr) of turbulent, 10$^6$ M$_{\odot}$ clouds with virial parameters ranging from 0.5 to 5. To model cluster formation, we use cluster sink particles, coupled to a raytracing scheme, and a custom subgrid model which populates a cluster via sampling an IMF with an efficiency of 20\% per freefall time. We find that radiative feedback only decreases the cluster particle formation efficiency by a few percent. The initial virial parameter plays a much stronger role in limiting cluster formation, with a spread of cluster formation efficiencies of 37\% to 71\% for the most unbound to the most bound model. The total number of clusters increases while the maximum mass cluster decreases with an increasing initial virial parameter, resulting in steeper mass distributions. The star formation rates in our cluster particles are initially consistent with observations but rise to higher values at late times. This suggests that radiative feedback alone is not responsible for dispersing a GMC over the first 5 Myr of cluster formation.