Speaker
Description
We investigate the Schmidt–Kennicutt relation and the star formation efficiency per free-fall time ($\epsilon_{\mathrm{ff}}$) in simulations of filamentary molecular clouds undergoing gravitational collapse. We study early evolutionary stages, with global star formation efficiencies of $\sim 2-10 \%$, using surface-density ($\Sigma$) maps like observational studies. Our simulations reproduce the observed Schmidt–Kennicutt scaling, including both the $\sim \Sigma^2$ dependence of the star formation rate (SFR) and the tighter correlation between SFR and $\Sigma/t_\mathrm{ff}$. We find low and nearly constant values of $\epsilon_{\mathrm{ff}}$ ($\approx 0.01-0.06$), consistent with observations. These results are naturally explained within the gravitational hierarchical collapse scenario, where collapsing structures develop $\sim r^{-2}$ density profiles, leading to self-similar scaling of mass and free-fall time. We find that the low $\epsilon_{\mathrm{ff}}$ arises because only a small fraction of the gas reaches high densities and collapses rapidly. We further argue that $\epsilon_{\mathrm{ff}}$ should not be interpreted as a true efficiency, but rather as the ratio of instantaneous SFR to gas inflow rate. Our results show that gravitational collapse alone can account for key observed properties of star-forming molecular clouds.
| Participate the oral/poster presentation award competition | No |
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