Non-universal star formation efficiency in turbulent ISM

Understand

We present a study of a star formation prescription in which star formation efficiency depends on local gas density and turbulent velocity dispersion, as suggested by direct simulations of SF in turbulent giant molecular clouds (GMCs).

• We test the model using a simulation of an isolated Milky Way-sized galaxy with a self-consistent treatment of turbulence on unresolved scales.
• We show that this prescription predicts a wide variation of local star formation efficiency per free-fall time, $\epsilon_{\rm ff} \sim 0.1 - 10\%$, and gas depletion time, $t_{\rm dep} \sim 0.1 - 10$ Gyr.
• In addition, it predicts an effective density threshold for star formation due to suppression of $\epsilon_{\rm ff}$ in warm diffuse gas stabilized by thermal pressure.