Molecular cloud formation by compression of magnetized turbulent gas subjected to radiative cooling

Abstract

Complex turbulent motions of magnetized gas are ubiquitous in the interstellar medium. The source of this turbulence, however, is still poorly understood. Previous work suggests that compression caused by supernova shockwaves, gravity, or cloud collisions, may drive the turbulence to some extent. In this work, we present three-dimensional (3D) magnetohydrodynamic (MHD) simulations of contraction in turbulent, magnetized clouds from the warm neutral medium (WNM) of the ISM to the formation of cold dense molecular clouds, including radiative heating and cooling. We study different contraction rates and find that observed molecular cloud properties, such as the temperature, density, Mach number, and magnetic field strength, and their respective scaling relations, are best reproduced when the contraction rate equals the turbulent turnover rate. In contrast, if the contraction rate is significantly larger (smaller) than the turnover rate, the compression drives too much (too little) turbulence, producing unrealistic cloud properties. We find that the density probability distribution function evolves from a double log-normal representing the two-phase ISM, to a skewed, single log-normal in the dense, cold phase. For purely hydrodynamical simulations, we find that the effective driving parameter of contracting cloud turbulence is natural to mildly compressive (\mbox{$b\sim 0.4$--$0.5$}), while for MHD turbulence, we find \mbox{$b\sim 0.3$--$0.4$}, i.e., solenoidal to naturally mixed. Overall, the physical properties of the simulated clouds that contract at a rate equal to the turbulent turnover rate, indicate that large-scale contraction may explain the origin and evolution of turbulence in the ISM.

arXiv comment18 pages, 9 figures. Accepted for publication in MNRAS

References in corpus (81)

• Theory of Star Formation
• Control of star formation by supersonic turbulence
• Astrophysical magnetic fields and nonlinear dynamo theory
• The Star Formation Rate and Dense Molecular Gas in Galaxies
• 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
• The Relationship Between Gas Content and Star Formation in Molecule-Rich Spiral Galaxies
• The Universality of the Stellar IMF
• The Resolved Properties of Extragalactic Giant Molecular Clouds
• The Energy Dissipation Rate of Supersonic, Magnetohydrodynamic Turbulence in Molecular Clouds
• The Density Probability Distribution in Compressible Isothermal Turbulence: Solenoidal versus Compressive Forcing
• Kinetic Energy Decay Rates of Supersonic and Super-Alfvenic Turbulence in Star-Forming Clouds
• The Universality of Turbulence in Galactic Molecular Clouds
• Magnetic Fields in Spiral Galaxies
• The Star Formation Rate of Supersonic MHD Turbulence
• Planck intermediate results. XXXV. Probing the role of the magnetic field in the formation of structure in molecular clouds
• Outflow Feedback Regulated Massive Star Formation in Parsec-Scale Cluster Forming Clumps
• A Super-Alfvenic Model of Dark Clouds
• Molecular Cloud Evolution II. From cloud formation to the early stages of star formation in decaying conditions
• An Origin of Supersonic Motions in Interstellar Clouds
• Density probability distribution in one-dimensional polytropic gas dynamics
• Thermal condensation in a turbulent atomic hydrogen flow
• On the Role of Massive Stars in the Support and Destruction of Giant Molecular Clouds
• Accretion-Driven Turbulence as Universal Process: Galaxies, Molecular Clouds, and Protostellar Disks
• On the universality of supersonic turbulence
• Density Fluctuations in MHD Turbulence: Spectra, Intermittency and Topology
• Mach Number Dependence of Turbulent Magnetic Field Amplification: Solenoidal versus Compressive Flows
• Numerical simulations of compressively driven interstellar turbulence: I. Isothermal gas
• Supersonic turbulence in the ISM: stellar extinction determinations as probes of the structure and dynamics of dark clouds
• The link between turbulence, magnetic fields, filaments, and star formation in the Central Molecular Zone cloud G0.253+0.016
• Cluster Formation in Protostellar Outflow-Driven Turbulence
• The Formation of Stellar Clusters in Turbulent Molecular Clouds: Effects of the Equation of State
• Effects of the Equation of State on the Formation of Star Clusters
• The Global Evolution of Giant Molecular Clouds. I: Model Formulation and Quasi-Equilibrium Behavior
• Supernova Driving. I. The Origin of Molecular Cloud Turbulence
• Modeling jet and outflow feedback during star cluster formation
• A robust numerical scheme for highly compressible magnetohydrodynamics: Nonlinear stability, implementation and tests
• A Holistic Scenario of Turbulent Molecular Cloud Evolution and Control of the Star Formation Efficiency. First Tests
• Magnetic field amplification in turbulent astrophysical plasmas
• Magnetic fields during the early stages of massive star formation - I. Accretion and disk evolution
• The Small-Scale Dynamo and Non-Ideal MHD in Primordial Star Formation
• The Global Evolution of Giant Molecular Clouds II: The Role of Accretion
• Physical Properties of Giant Molecular Clouds in the Large Magellanic Cloud
• Thermal Instability-Induced Interstellar Turbulence
• Molecular Cloud Evolution III. Accretion vs. stellar feedback
• A Model for (Non-Lognormal) Density Distributions in Isothermal Turbulence
• 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
• Adiabatic Heating of Contracting Turbulent Fluids
• Magnetic Fields and the Triaxiality of Molecular Cloud Cores
• On the structure of the turbulent interstellar atomic hydrogen. I- Physical characteristics
• The Turbulence Spectrum of Molecular Clouds in the Galactic Ring Survey: A Density-Dependent PCA Calibration
• Ionization compression impact on dense gas distribution and star formation, Probability density functions around H ii regions as seen by Herschel
• Moving mesh simulations of star forming cores in magneto-gravo-turbulence
• Supernova Driving. IV. The Star Formation Rate of Molecular Clouds
• The origin of physical variations in the star formation law
• Magnetic field amplification during gravitational collapse - Influence of initial conditions on dynamo evolution and saturation
• Formation of Cold Filamentary Structure from Wind Blown Superbubbles
• The structure and statistics of interstellar turbulence
• The Density and Temperature of Molecular Clouds in M33
• The Star Formation Rate of Molecular Clouds
• Formation of proto-cluster: a virialized structure from gravo-turbulent collapse I. Simulation of cluster formation in collapsing molecular cloud
• Improved VLBI astrometry of OH maser stars
• Testing Star Formation Laws in a Starburst Galaxy At Redshift 3 Resolved with ALMA
• The Molecular Interstellar Medium of the Local Group Dwarf NGC6822
• Supernova Feedback in Molecular Clouds: Global Evolution and Dynamics
• Supernova Driving. II. Compressive Ratio in Molecular-Cloud Turbulence
• The small-scale dynamo: Breaking universality at high Mach numbers
• On the shape and completeness of the column density probability distribution function of molecular clouds
• On the effective turbulence driving mode of molecular clouds formed in disc galaxies
• The Density Distribution in Turbulent Bi-stable Flows
• Testing Star Formation Laws on Spatially Resolved Regions in a $z\approx 4.3$ Starburst Galaxy
• Supernova Driving. III. Synthetic Molecular Cloud Observations
• The driving of turbulence in simulations of molecular cloud formation and evolution
• A Young GMC Formed at the Interface of Two Colliding Supershells: Observations Meet Simulations
• The role of initial magnetic field structure in the launching of protostellar jets
• The relation between the turbulent Mach number and observed fractal dimensions of turbulent clouds
• Scaling Laws and Intermittency in Highly Compressible Turbulence
• An ATCA Survey of HI Absorption in the Magellanic Clouds I: HI Gas Temperature Measurements in the Small Magellanic Cloud
• The relation between the true and observed fractal dimensions of turbulent clouds
• Compression of turbulent magnetized gas in Giant Molecular Clouds

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• The sonic scale revealed by the world's largest supersonic turbulence simulation
• The molecular cloud lifecycle
• Understanding star formation in molecular clouds IV. Column density PDFs from quiescent to massive molecular clouds
• Turbulent dynamo in the two-phase interstellar medium
• Shock-multicloud interactions in galactic outflows -- II. Radiative fractal clouds and cold gas thermodynamics
• Impact of relativistic jets on the star formation rate: a turbulence-regulated framework
• Magnetic field fluctuations in anisotropic, 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
• Turbulent diffusion of streaming cosmic rays in compressible, partially ionised plasma
• Gravity Versus Magnetic Fields in Forming Molecular Clouds
• First extragalactic measurement of the turbulence driving parameter: ALMA observations of the star-forming region N159E in the Large Magellanic Cloud
• Amplification of turbulence in contracting prestellar cores in primordial minihalos
• Non-adiabatic turbulence driving during gravitational collapse
• A new method for spatially resolving the turbulence driving mixture in the ISM with application to the Small Magellanic Cloud
• Amplification and saturation of turbulent magnetic field in collapsing primordial gas clouds
• Low star formation efficiency due to turbulent adiabatic compression in the Taffy bridge
• Saturation level of turbulence in collapsing gas clouds
• The turbulence driving parameter of molecular clouds in disc galaxies
• Taking control of compressible modes: bulk viscosity and the turbulent dynamo
• Amplification and generation of turbulence during self-gravitating collapse