Feedback and star formation efficiency in high-mass star-forming regions

ABSTRACT To advance our understanding of massive star formation, it is essential to perform a comprehensive suite of simulations that explore the relevant parameter space and include enough physics to enable a comparison with observational data. We simulate the gravitational collapse of isolated parsec-scale turbulent cores using the flash code, modelling stars as sink particles. Our simulations incorporate ionizing radiation and the associated radiation pressure from stellar sources, and non-ionizing radiation and its dust heating, along with self-consistent chemistry, to capture the properties of emerging ultra-compact H ii regions. Dust, gas, and radiation temperature are computed independently. The initial conditions are informed by ALMAGAL observations. We assess stellar feedback, comparing ionizing radiation and radiation pressure. Ionizing radiation ultimately halts mass accretion onto sink particles, while direct radiation pressure enhances the expansion of H ii regions. Heating from non-ionizing radiation suppresses fragmentation. We examine the effect of spatial resolution, finding that higher resolution leads to more sink particles, which are situated in environments with higher densities. As a result, ionizing radiation remains trapped longer, allowing continued accretion and yielding a higher overall star formation efficiency (SFE). We explore the impact of varying initial conditions, including the core density profile, virial parameter, and metallicity. Our parameter study reveals that a flatter density profile, higher virial parameter, and increased metallicity promote fragmentation, potentially enhancing the SFE by slowing the growth of the most massive stars and delaying the onset of stellar feedback. Overall, we find SFEs between 35 per cent and 57 per cent. Stellar feedback dictates the final SFE.