SIMBAD references

We apply gravity- and density-based methods to identify clouds in self-consistent numerical simulations of the star-forming, multiphase interstellar medium (ISM) and compare their properties and global correlation with the star formation rate (SFR) over time. The gravity-based method identifies bound objects, which have masses M∼10³–10⁴M_☉ at densities n_H∼100cm^–3, and virial parameters α_v ∼ 0.5-5. For clouds defined by a density threshold n_H,{min}, the average virial parameter decreases, and the fraction of material that is genuinely bound increases, with increasing n_H,{min}. Surprisingly, clouds defined by density thresholds can be unbound even when α_v < 2, and high-mass clouds (10⁴–10⁶M_☉) are generally unbound. This suggests that the traditional α_v is at best an approximate measure of boundedness in the ISM. All clouds have internal turbulent motions increasing with size as σ ∼1kms^–1(R/pc)^1/2, similar to observed relations. Bound structures comprise a small fraction of the total simulation mass and have a star formation efficiency per freefall time ε_ff ∼ 0.4. For n_H,{min}=10–100cm^–3, ε_ff ∼ 0.03-0.3, increasing with density threshold. A temporal correlation analysis between SFR(t) and aggregate mass M(n_H,{min};t) at varying n_H,{min} shows that time delays to star formation are t_delay∼t_ff(n_H,{min}). The correlation between SFR(t) and M(n_H,{min};t) systematically tightens at higher n_H,{min}. Considering moderate-density gas, selecting against high virial parameter clouds improves correlation with the SFR, consistent with previous work. Even at high n_H,{min}, the temporal dispersion in (SFR-ε_ffM/t_ff)/<SFR>is ∼50%, due to the large-amplitude variations and inherent stochasticity of the system.