Inefficient star formation in high Mach number environments II. Numerical simulations and comparison with analytical models

Abstract

Predicting the star formation rate (SFR) in galaxies is crucial to understand their evolution and morphology. To do so requires a fine understanding of how dense structures of gas are created and collapse. In that, turbulence and gravity play a major role. Within the gravo-turbulent framework, we assume that turbulence shapes the ISM, creating density fluctuations that, if gravitationally unstable, will collapse and form stars. The goal of this work is to quantify how different regimes of turbulence, characterized by the strength and compressibility of the driving, shape the density field. We are interested in the outcome in terms of SFR and how it compares with existing analytical models for the SFR. We run a series of hydrodynamical simulations of turbulent gas. The simulations are first conducted without gravity, so that the density and velocity are shaped by the turbulence driving. Gravity is then switched on, and the SFR is measured and compared with analytical models. The physics included in these simulations is very close to the one assumed in the classical gravo-turbulent SFR analytical models, which makes the comparison straightforward. We found that the existing analytical models convincingly agree with simulations at low Mach number, but we measure a much lower SFR in the simulation with a high Mach number. We develop, in a companion paper, an updated physically-motivated SFR model that reproduces well the inefficient high Mach regime of the simulations. Our work demonstrates that accurate estimations of the turbulent-driven replenishment time of dense structures and the dense gas spatial distribution are necessary to correctly predict the SFR in the high Mach regime. The inefficient high-Mach regime is a possible explanation for the low SFR found in dense and turbulent environments such as the centers of our Milky Way and other galaxies.

13 pages, 14 figures, accepted for publication in A&A

References in corpus (16)

• On the Star Formation Efficiency of Turbulent Magnetized Clouds
• On the Density Distribution in Star-forming Interstellar Clouds
• Numerical simulations of compressively driven interstellar turbulence: I. Isothermal gas
• Modelling the supernova-driven ISM in different environments
• Towards a more realistic sink particle algorithm for the RAMSES code
• First results from SMAUG: Characterization of Multiphase Galactic Outflows from a Suite of Local Star-Forming Galactic Disk Simulations
• Simulations of magnetized multiphase galactic disk regulated by supernovae explosions
• The density structure and star formation rate of non-isothermal polytropic turbulence
• Star Formation Laws and Efficiencies across 80 Nearby Galaxies
• Star formation laws and thresholds from ISM structure and turbulence
• SILCC VII -- Gas kinematics and multiphase outflows of the simulated ISM at high gas surface densities
• Large-scale turbulent driving regulates star formation in high-redshift gas-rich galaxies
• Gravity Versus Magnetic Fields in Forming Molecular Clouds
• Impact of magneto-rotational instability on grain growth in protoplanetary disks: II. Increased grain collisional velocities
• Large-scale turbulent driving regulates star formation in high-redshift gas-rich galaxies II: Influence of the magnetic field and the turbulent compressive fraction
• Inefficient star formation in high Mach number environments I. The turbulent support analytical model

Cited by in corpus (4)

• Inefficient star formation in high Mach number environments I. The turbulent support analytical model
• Impact of star formation models on the growth of simulated galaxies at high redshifts
• Estimating the dense gas mass of molecular clouds using spatially unresolved 3 mm line observations
• The interdependence between density PDF, CMF and IMF and their relation with Mach number in simulations