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arXiv · 2109.08160

The challenge of simulating the star cluster population of dwarf galaxies with resolved interstellar medium

Jessica M. Hislop·Thorsten Naab·Ulrich P. Steinwandel·Natalia Lahén·Dimitrios Irodotou·Peter H. Johansson·Stefanie Walch
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Abstract

We present results on the star cluster properties from a series of high resolution smoothed particles hydrodynamics (SPH) simulations of isolated dwarf galaxies as part of the GRIFFIN project. The simulations at sub-parsec spatial resolution and a minimum particle mass of 4 $\mathrm{M_\odot}$ incorporate non-equilibrium heating, cooling and chemistry processes, and realise individual massive stars. All the simulations follow feedback channels of massive stars that include the interstellar-radiation field, that is variable in space and time, the radiation input by photo-ionisation and supernova explosions. Varying the star formation efficiency per free-fall time in the range $ε_\mathrm{ff}$ = 0.2 - 50$\%$ neither changes the star formation rates nor the outflow rates. While the environmental densities at star formation change significantly with $ε_\mathrm{ff}$, the ambient densities of supernovae are independent of $ε_\mathrm{ff}$ indicating a decoupling of the two processes. At low $ε_\mathrm{ff}$, more massive, and increasingly more bound star clusters are formed, which are typically not destroyed. With increasing $ε_\mathrm{ff}$ there is a trend for shallower cluster mass functions and the cluster formation efficiency $Γ$ for young bound clusters decreases from $50 \%$ to $\sim 1 \%$ showing evidence for cluster disruption. However, none of our simulations form low mass ($< 10^3$ $\mathrm{M_\odot}$) clusters with structural properties in perfect agreement with observations. Traditional star formation models used in galaxy formation simulations based on local free-fall times might therefore not be able to capture low mass star cluster properties without significant fine-tuning.

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Jessica M. Hislop, Thorsten Naab, Ulrich P. Steinwandel, Natalia Lahén, Dimitrios Irodotou, Peter H. Johansson, Stefanie Walch. 2021-11-16. The challenge of simulating the star cluster population of dwarf galaxies with resolved interstellar medium. https://doi.org/10.1093/mnras%2Fstab3347

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