Does God play dice with star clusters?

Abstract

When a detailed model of a stellar population is unavailable, it is most common to assume that stellar masses are independently and identically distributed according to some distribution: the universal initial mass function (IMF). However, stellar masses resulting from causal, long-ranged physics cannot be truly random and independent, and the IMF may vary with environment. To compare stochastic sampling with a physical model, we run a suite of 100 STARFORGE radiation magnetohydrodynamics simulations of low-mass star cluster formation in $2000M_{\odot }$ clouds that form $\sim 200$ stars each on average. The stacked IMF from the simulated clouds has a sharp truncation at $\sim 28M_{\odot }$, well below the typically-assumed maximum stellar mass $M_{\mathrm{up}}\sim 100-150M_{\odot }$ and the total cluster mass. The sequence of star formation is not totally random: massive stars tend to start accreting sooner and finish later than the average star. However, final cluster properties such as maximum stellar mass and total luminosity have a similar amount of cloud-to-cloud scatter to random sampling. Therefore stochastic sampling does not generally model the stellar demographics of a star cluster as it is forming, but may describe the end result fairly well, if the correct IMF -- and its environment-dependent upper cutoff -- are known.

Accepted for publication in Open Journal of Astrophysics

References in corpus (8)

• The Effects of Radiative Transfer on Low-Mass Star Formation
• Circumventing the radiation pressure barrier in the formation of massive stars via disk accretion
• A Possible Origin of the Mass-Metallicity Relation of Galaxies
• The dynamics and outcome of star formation with jets, radiation, winds, and supernovae in concert
• How fast do young star clusters expel their natal gas?: Estimating the upper limit of the gas expulsion time-scale
• Sampling methods for stellar masses and the mmax-Mecl relation in the starburst dwarf galaxy NGC 4214
• Are turbulent spheres suitable initial conditions for star-forming clouds?
• Do simulated molecular clouds look like real ones?

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• Deriving physical parameters of unresolved star clusters. VIII. Limits of aperture photometry for star cluster studies
• Gauging the Impact of Cosmic Ray Feedback on the Stellar Initial Mass Function
• Stellar Feedback Effects on the Mass Distribution of Clouds and Cloud Complexes