The density structure of supersonic self-gravitating turbulence

Abstract

We conduct numerical experiments to determine the density probability distribution function (PDF) produced in supersonic, isothermal, self-gravitating turbulence of the sort that is ubiquitous in star-forming molecular clouds. Our experiments cover a wide range of turbulent Mach number and virial parameter, allowing us for the first time to determine how the PDF responds as these parameters vary, and we introduce a new diagnostic, the dimensionless star formation efficiency versus density (${\epsilon }_{\mathrm{ff}}(s)$) curve, which provides a sensitive diagnostic of the PDF shape and dynamics. We show that the PDF follows a universal functional form consisting of a log-normal at low density with two distinct power law tails at higher density; the first of these represents the onset of self-gravitation, and the second reflects the onset of rotational support. Once the star formation efficiency reaches a few percent, the PDF becomes statistically steady, with no evidence for secular time-evolution at star formation efficiencies from about five to 20 percent. We show that both the Mach number and the virial parameter influence the characteristic densities at which the log-normal gives way to the first power-law, and the first to the second, and we extend (for the former) and develop (for the latter) simple theoretical models for the relationship between these density thresholds and the global properties of the turbulent medium.

arXiv comment18 pages, 10 figures, accepted in MNRAS, revised version

References in corpus (102)

• A Multi-Code Analysis Toolkit for Astrophysical Simulation Data
• A General Theory of Turbulence-Regulated Star Formation, From Spirals to ULIRGs
• Density, Velocity, and Magnetic Field Structure in Turbulent Molecular Cloud Models
• Comparing the statistics of interstellar turbulence in simulations and observations: Solenoidal versus compressive turbulence forcing
• The Star Formation Rate of Turbulent Magnetized Clouds: Comparing Theory, Simulations, and Observations
• On the Star Formation Rates in Molecular Clouds
• The Statistics of Supersonic Isothermal Turbulence
• Analytical theory for the initial mass function: CO clumps and prestellar cores
• The Universality of the Stellar IMF
• The Density Probability Distribution in Compressible Isothermal Turbulence: Solenoidal versus Compressive Forcing
• The Star Formation Rate and Gas Surface Density Relation in the Milky Way: Implications for Extragalactic Studies
• The Star Formation Rate of Supersonic MHD Turbulence
• Modeling Collapse and Accretion in Turbulent Gas Clouds: Implementation and Comparison of Sink Particles in AMR and SPH
• On the Star Formation Efficiency of Turbulent Magnetized Clouds
• Density probability distribution in one-dimensional polytropic gas dynamics
• Star Formation from Galaxies to Globules
• The Big Problems in Star Formation: the Star Formation Rate, Stellar Clustering, and the Initial Mass Function
• One-Point Probability Distribution Functions of Supersonic Turbulent Flows in Self-Gravitating Media
• The "Mysterious" Origin of Brown Dwarfs
• Analytical star formation rate from gravoturbulent fragmentation
• What determines the density structure of molecular clouds ? A case study of Orion B with Herschel
• On the Density Distribution in Star-forming Interstellar Clouds
• Embedding Lagrangian Sink Particles in Eulerian Grids
• Inefficient star formation through turbulence, magnetic fields and feedback
• Gravity or Turbulence? The velocity dispersion-size relation
• Numerical simulations of compressively driven interstellar turbulence: I. Isothermal gas
• Clouds as Turbulent Density Fluctuations. Implications for pressure confinement and spectral line data interpretation
• The link between turbulence, magnetic fields, filaments, and star formation in the Central Molecular Zone cloud G0.253+0.016
• Radiation-Hydrodynamic Simulations of the Formation of Orion-Like Star Clusters II. The Initial Mass Function from Winds, Turbulence, and Radiation
• Fragmentation of Massive Protostellar Disks
• Two regimes of Turbulent Fragmentation and the stellar IMF from Primordial to Present Day Star Formation
• Modeling jet and outflow feedback during star cluster formation
• Analytical theory for the initial mass function: II. Properties of the flow
• A robust numerical scheme for highly compressible magnetohydrodynamics: Nonlinear stability, implementation and tests
• On the evolution of the density pdf in strongly self-gravitating systems
• Protostellar Disks: Formation, Fragmentation, and the Brown Dwarf Desert
• A General Theory of Turbulent Fragmentation
• The density variance -- Mach number relation in supersonic, isothermal turbulence
• Cloud Scale ISM Structure and Star Formation in M51
• Turbulent Molecular Cloud Cores: Rotational Properties
• The sonic scale revealed by the world's largest supersonic turbulence simulation
• Unfolding the Laws of Star Formation: The Density Distribution of Molecular Clouds
• The Two States of Star Forming Clouds
• Characterizing Magnetohydrodynamic Turbulence in the Small Magellanic Cloud
• A Direct Multigrid Poisson Solver for Oct-Tree Adaptive Meshes
• Molecular clouds have power-law probability distribution functions
• The Turbulent Warm Ionized Medium: Emission Measure Distribution and MHD Simulations
• The Star Formation Rate in the Gravoturbulent Interstellar Medium
• A Fractal Origin for the Mass Spectrum of Interstellar Clouds: II. Cloud Models and Power Law Slopes
• Star Cluster Formation in Turbulent, Magnetized Dense Clumps with Radiative and Outflow Feedback
• Understanding star formation in molecular clouds I. Effects of line-of-sight contamination on the column density structure
• A Model for (Non-Lognormal) Density Distributions in Isothermal Turbulence
• The Virial Balance of Clumps and Cores in Molecular Clouds
• The density structure and star formation rate of non-isothermal polytropic turbulence
• A comparison between grid and particle methods on the statistics of driven, supersonic, isothermal turbulence
• A new density variance - Mach number relation for subsonic and supersonic, isothermal turbulence
• Star Formation Relations in the Milky Way
• A method for reconstructing the variance of a 3D physical field from 2D observations: Application to turbulence in the ISM
• Ionization compression impact on dense gas distribution and star formation, Probability density functions around H ii regions as seen by Herschel
• Detection of two power-law tails in the probability distribution functions of massive GMCs
• The Column Density Variance-Sonic Mach Number Relationship
• Density Probability Distribution Functions in Supersonic Hydrodynamic and MHD Turbulence
• Moving mesh simulations of star forming cores in magneto-gravo-turbulence
• Star Formation in Self-Gravitating Turbulent Fluids
• Understanding star formation in molecular clouds II. Signatures of gravitational collapse of IRDCs
• The origin of physical variations in the star formation law
• The shapes of column density PDFs - The importance of the last closed contour
• The Effects of Magnetic Fields and Protostellar Feedback on Low-mass Cluster Formation
• Observational Diagnostics of Self-Gravitating MHD Turbulence in Giant Molecular Clouds
• The rate and latency of star formation in dense, massive clumps in the Milky Way
• On The Nature of Variations in the Measured Star Formation Efficiency of Molecular Clouds
• Density probability distribution functions of diffuse gas in the Milky Way
• Droplets I: Pressure-Dominated Sub-0.1 pc Coherent Structures in L1688 and B18
• A method for reconstructing the PDF of a 3D turbulent density field from 2D observations
• The Razor's Edge of Collapse: The Transition Point from Lognormal to Powerlaw in Molecular Cloud PDFs
• The Self-gravitating Gas Fraction and The Critical Density for Star Formation
• A $Herschel-SPIRE$ Survey of the Mon R2 Giant Molecular Cloud: Analysis of the Gas Column Density Probability Density Function
• Mass and Magnetic distributions in Self Gravitating Super Alfvenic Turbulence with AMR
• Cloud Structure of Galactic OB Cluster Forming Regions from Combining Ground and Space Based Bolometric Observations
• The Single-Cloud Star Formation Relation
• Collapse in Self-gravitating Turbulent Fluids
• The Anatomy of the Column Density Probability Distribution Function (N-PDF)
• Numerical Calibration of the HCN$-$Star Formation Correlation
• A measurement of the turbulence-driven density distribution in a non-star-forming molecular cloud
• On the Observed Diversity of Star Formation Efficiencies in Giant Molecular Clouds
• Evolution of the density PDF in star forming clouds: the role of gravity
• The Probability Distribution of Density Fluctuations in Supersonic Turbulence
• On the turbulence driving mode of expanding HII regions
• On the compressive nature of turbulence driven by ionising feedback in the pillars of the Carina Nebula
• Relationship between turbulence energy and density variance in the Solar neighbourhood molecular clouds
• The structure and characteristic scales of molecular clouds
• Density distribution function of a self-gravitating isothermal compressible turbulent fluid in the context of Molecular Clouds ensembles
• Implementation of stellar heating feedback in simulations of star cluster formation: effects on the initial mass function
• On the extraction of power-law parts of the probability density functions in star-forming clouds
• Notes on Star Formation
• Detailed Balance and Exact Results for Density Fluctuations in Supersonic Turbulence
• Determining Star Formation Thresholds from Observations
• The Nature of Turbulence in the LITTLE THINGS Dwarf Irregular Galaxies
• Density distribution function of a self-gravitating isothermal compressible turbulent fluid in the context of Molecular Clouds ensembles II: the contribution of the turbulent term and the potential of the outer shells
• Turbulence and Star Formation in a Sample of Spiral Galaxies
• Density PDFs of Super-Sonic Turbulence
• The turbulence driving parameter of molecular clouds in disc galaxies

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• Escaping the maze: a statistical sub-grid model for cloud-scale density structures in the interstellar medium
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• A two-phase model of galaxy formation: III. The formation of globular clusters
• Multi log-normal density structure in Cygnus-X molecular clouds: A fitting for N-PDF without power-law
• Density Exponent Analysis: Gravity-driven steepening of the density profiles of star-forming regions
• Density distribution function of a self-gravitating isothermal turbulent fluid in the context of molecular clouds ensembles -- III. Virial analysis
• Structure of iso-density sets in supersonic isothermal turbulence
• Impact of the shape of the prestellar density fluctuations on the core mass function
• CO mapping of Cygnus-X -- volume density distribution
• Recovering the properties of the interstellar medium through integrated spectroscopy: application to the z~0 ECO volume-limited star-forming galaxy sample
• Sub-kpc scale gas density histogram of the Galactic molecular gas: a new statistical method to characterise galactic-scale gas structures
• Contour Analysis Tool: an interactive tool for background and morphology analysis