Testing the Turbulent Origin of the Stellar Initial Mass Function

Abstract

Supersonic turbulence in the interstellar medium (ISM) is closely linked to the formation of stars, and hence many theories connect the stellar initial mass function (IMF) with the turbulent properties of molecular clouds. Here we test three turbulence-based IMF models (by Padoan & Nordlund 2002, Hennebelle & Chabrier 2008, and Hopkins 2012), which predict the relation between the high-mass slope ($\Gamma$) of the IMF, $\mathrm{d}N/\mathrm{d}\log M\propto M^{\Gamma }$ and the exponent n of the velocity power spectrum of turbulence, $E_v(k)\propto k^{-n}$, where $n\approx 2$ corresponds to typical ISM turbulence. Using hydrodynamic simulations, we drive turbulence with an unusual index of $n\approx 1$, measure $\Gamma$, and compare the results with $n\approx 2$. We find that reducing $n$ from 2 to 1 primarily changes the high-mass region of the IMF (beyond the median mass), where we measure high-mass slopes within the 95 per cent confidence interval of $-1.5<\Gamma <-1$ for $n\approx 1$ and $-3.7<\Gamma <-2.4$ for $n\approx 2$, respectively. Thus, we find that $n=1$ results in a significantly flatter high-mass slope of the IMF, with more massive stars formed than for $n\approx 2$. We compare these simulations with the predictions of the three IMF theories. We find that while the Padoan & Nordlund theory matches our simulations with fair accuracy, the other theories either fail to reproduce the main qualitative outcome of the simulations or require some modifications. We conclude that turbulence plays a key role in shaping the IMF, with a shallower turbulence power spectrum producing a shallower high-mass IMF, and hence more massive stars.

References in corpus (45)

• emcee: The MCMC Hammer
• Galactic Stellar and Substellar Initial Mass Function
• On the variation of the Initial Mass Function
• Theory of Star Formation
• From filamentary clouds to prestellar cores to the stellar IMF: Initial highlights from the Herschel Gould Belt survey
• Interstellar Turbulence I: Observations and Processes
• The Stellar IMF from Turbulent Fragmentation
• A Universal Stellar Initial Mass Function? A Critical Look at Variations
• 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 Statistics of Supersonic Isothermal Turbulence
• Analytical theory for the initial mass function: CO clumps and prestellar cores
• Dissipation in Compressible MHD Turbulence
• The Universality of the Stellar IMF
• The Universality of Turbulence in Galactic Molecular Clouds
• Modeling Collapse and Accretion in Turbulent Gas Clouds: Implementation and Comparison of Sink Particles in AMR and SPH
• The initial mass function : from Salpeter 1955 to 2005
• The Big Problems in Star Formation: the Star Formation Rate, Stellar Clustering, and the Initial Mass Function
• The Effects of Radiative Transfer on Low-Mass Star Formation
• A new Jeans resolution criterion for (M)HD simulations of self-gravitating gas: Application to magnetic field amplification by gravity-driven turbulence
• On the universality of supersonic turbulence
• Embedding Lagrangian Sink Particles in Eulerian Grids
• The stellar and sub-stellar IMF of simple and composite populations
• Inefficient star formation through turbulence, magnetic fields and feedback
• Two regimes of Turbulent Fragmentation and the stellar IMF from Primordial to Present Day Star Formation
• The Stellar IMF, Core Mass Function, & The Last-Crossing Distribution
• 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
• A General Theory of Turbulent Fragmentation
• Turbulent Driving Scales in Molecular Clouds
• A Direct Multigrid Poisson Solver for Oct-Tree Adaptive Meshes
• The Dawes Review 8: Measuring the Stellar Initial Mass Function
• Density Power Spectrum of Compressible Hydrodynamic Turbulent Flows
• Infall-Driven Protostellar Accretion and the Solution to the Luminosity Problem
• The Origin and Universality of the Stellar Initial Mass Function
• The dependence of star formation on initial conditions and molecular cloud structure
• The Turbulence Spectrum of Molecular Clouds in the Galactic Ring Survey: A Density-Dependent PCA Calibration
• On the Origin of Stellar Masses
• The stellar IMF from Isothermal MHD Turbulence
• The dependence of the sub-stellar IMF on the initial conditions for star formation
• What Physics Determines the Peak of the IMF? Insights from the Structure of Cores in Radiation-Magnetohydrodynamic Simulations
• Mapping the core mass function to the initial mass function
• Star formation in molecular cores III. The effect of the turbulent power spectrum
• Mach number study of supersonic turbulence: The properties of the density field
• Implementation of stellar heating feedback in simulations of star cluster formation: effects on the initial mass function

Cited by in corpus (16)

• The IMF and multiplicity of stars from gravity, turbulence, magnetic fields, radiation and outflow feedback
• The role of the turbulence driving mode for the Initial Mass Function
• A new method for measuring the 3D turbulent velocity dispersion of molecular clouds
• The statistical properties of stars at redshift, z=5, compared with the present epoch
• The spectrum of magnetized turbulence in the interstellar medium
• Energy balance and Alfvén Mach numbers in compressible magnetohydrodynamic turbulence with a large-scale magnetic field
• Environmental variation of the low-mass IMF
• Variation of the low-mass end of the stellar initial mass function with redshift and metallicity
• Recovery of the low- and high-mass end slopes of the IMF in massive early-type galaxies using detailed elemental abundances
• The Fornax3D project: Intrinsic Correlations between Orbital Properties and the Stellar Initial Mass Function
• The influence of the cloud virial parameter on the initial mass function
• Length-scales and Dynamics of Carina's Western Wall
• Star Cluster Formation in Clouds with Externally Driven Turbulence
• Protostellar disc structure and dynamics during star formation from cloud-scale initial conditions
• Star Formation
• The interdependence between density PDF, CMF and IMF and their relation with Mach number in simulations