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Title: Nonuniversal star formation efficiency in turbulent ISM

Journal Article · · Astrophysical Journal

We present a study of a star formation prescription in which star formation efficiency (SFE) 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 SFE per free-fall time, ϵ{sub ff} ∼ 0.1%–10%, and gas depletion time, t{sub dep} ∼ 0.1–10 Gyr. In addition, it predicts an effective density threshold for star formation due to suppression of ϵ{sub ff} in warm diffuse gas stabilized by thermal pressure. We show that the model predicts star formation rates (SFRs) in agreement with observations from the scales of individual star-forming regions to the kiloparsec scales. This agreement is nontrivial, as the model was not tuned in any way and the predicted SFRs on all scales are determined by the distribution of the GMC-scale densities and turbulent velocities σ in the cold gas within the galaxy, which is shaped by galactic dynamics. The broad agreement of the star formation prescription calibrated in the GMC-scale simulations with observations both gives credence to such simulations and promises to put star formation modeling in galaxy formation simulations on a much firmer theoretical footing.

OSTI ID:
22868844
Journal Information:
Astrophysical Journal, Vol. 826, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
Country of Publication:
United States
Language:
English

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What Sets the Slope of the Molecular Kennicutt–Schmidt Relation? journal January 2019
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What FIREs up star formation: the emergence of the Kennicutt–Schmidt law from feedback text January 2018
Forming early-type galaxies without AGN feedback: a combination of merger-driven outflows and inefficient star formation text January 2020
FIRE-2 simulations: physics versus numerics in galaxy formation text January 2018
Observational Evidence of Dynamic Star Formation Rate in Milky Way Giant Molecular Clouds text January 2016
What drives gravitational instability in nearby star-forming spirals? The impact of CO and HI velocity dispersions text January 2017
Star Cluster Formation in Cosmological Simulations. II. Effects of Star Formation Efficiency and Stellar Feedback text January 2017
On the Appearance of Thresholds in the Dynamical Model of Star Formation text January 2018
Globular Cluster Formation and Evolution in the Context of Cosmological Galaxy Assembly: Open Questions text January 2018
The Fate of Supernova-Heated Gas in Star-Forming Regions of the LMC: Lessons for Galaxy Formation? text January 2018
An uncertainty principle for star formation - II. A new method for characterising the cloud-scale physics of star formation and feedback across cosmic history text January 2018
The [CII]--SFR correlation in dwarf galaxies across cosmic time text January 2019
Fast and inefficient star formation due to short-lived molecular clouds and rapid feedback text January 2019
Forming early-type galaxies without AGN feedback: a combination of merger-driven outflows and inefficient star formation text January 2019