On the coupled origin of the stellar IMF and multiplicity

Abstract

In the solar neighborhood, the Initial Mass Function (IMF) follows is canonically described by the Salpeter power-law slope for the high-mass range. The stellar IMF may directly result from a Core Mass Function (CMF) through accretion, gravitational collapse, and fragmentation. This inheritance implies that the mass of the gaseous fragments may be connected to the properties of clustered and multiple stellar systems. We aim to (i) quantify the influence of hierarchical fragmentation of cores on the resulting IMF, and (ii) determine the consequences of this fragmentation on the multiplicity of the stellar systems. We employed a scale-free, hierarchical fragmentation model to investigate the fragmentation of top-heavy CMF. Hierarchical fragmentation of gas clumps shifts the CMF towards lower mass range and can modify its shape. Starting from the top-heavy power-law CMF observed in W43-MM2&MM3 star forming region, we show that at least four levels of hierarchical fragmentation are required to generate the turn-over peak of the cIMF. Within a radius of 0.2-2.5 kAU, massive stars (M > 10 Msun) have on average 0.9 companions, five times fewer than low-mass stars (M < 0.1 Msun); the latter are less dynamically stable and should disperse. We show that a universal IMF can emerge from mass-dependent fragmentation processes provided that more massive cores produce less fragments compared to lower mass cores and transfer their mass less efficiently to their fragments. Hierarchical fragmentation alone cannot reconcile a universal IMF with observed stellar multiplicity. We propose that fragmentation is not scale-free but operates in two distinct regimes: a mass-dependent phase establishing the Salpeter slope and a mass-independent phase setting the turn-over. Our framework provides a way to compare core subfragmentation in various star-forming regions and numerical simulations.

References in corpus (69)

• Galactic Stellar and Substellar Initial Mass Function
• On the variation of the Initial Mass Function
• Embedded Clusters in Molecular Clouds
• From filamentary clouds to prestellar cores to the stellar IMF: Initial highlights from the Herschel Gould Belt survey
• Stellar Multiplicity
• Toward Understanding Massive Star Formation
• The Stellar IMF from Turbulent Fragmentation
• A Universal Stellar Initial Mass Function? A Critical Look at Variations
• Analytical theory for the initial mass function: CO clumps and prestellar cores
• Stellar, brown dwarf and multiple star properties from a radiation hydrodynamical simulation of star cluster formation
• The Universality of the Stellar IMF
• The mass function of dense molecular cores and the origin of the IMF
• Early Star Formation and the Evolution of the Stellar Initial Mass Function in Galaxies
• The maximum stellar mass, star-cluster formation and composite stellar populations
• The Big Problems in Star Formation: the Star Formation Rate, Stellar Clustering, and the Initial Mass Function
• An upper limit to the masses of stars
• A Theory of the IMF for Star Formation in Molecular Clouds
• Stellar Populations in the Central 0.5 pc of the Galaxy II: The Initial Mass Function
• Evidence for top-heavy stellar initial mass functions with increasing density and decreasing metallicity
• On the Density Distribution in Star-forming Interstellar Clouds
• The stellar and sub-stellar IMF of simple and composite populations
• Evidence for a fundamental stellar upper mass limit from clustered star formation
• Accretion in stellar clusters and the IMF
• Stellar populations dominated by massive stars in dusty starburst galaxies across cosmic time
• A SCUBA survey of Orion, the low-mass end of the core mass function
• Comparing Star Formation on Large Scales in the c2d Legacy Clouds: Bolocam 1.1 mm Dust Continuum Surveys of Serpens, Perseus, and Ophiuchus
• The Fragmentation of Magnetized, Massive Star-Forming Cores with Radiative Feedback
• The Stellar IMF, Core Mass Function, & The Last-Crossing Distribution
• A General Theory of Turbulent Fragmentation
• The unexpectedly large proportion of high-mass star-forming cores in a Galactic mini-starburst
• On the function describing the stellar initial mass function
• The Dawes Review 8: Measuring the Stellar Initial Mass Function
• The Parallax of W43: a Massive Star Forming Complex near the Galactic Bar
• Properties of the dense core population in Orion B as seen by the Herschel Gould Belt survey
• On the origin of brown dwarfs and free-floating planetary mass objects
• Fibers in the NGC1333 proto-cluster
• The Unusual Initial Mass Function of the Arches Cluster
• The Herschel view of the dense core population in the Ophiuchus molecular cloud
• Variations in the Stellar IMF: from Bottom to Top
• The Stellar Initial Mass Function in Early-Type Galaxies From Absorption Line Spectroscopy. IV. A Super-Salpeter IMF in the center of NGC 1407 from Non-Parametric Models
• Variability in the stellar initial mass function at low and high mass: 3-component IMF models
• The role of molecular filaments in the origin of the prestellar core mass function and stellar initial mass function
• The W43-MM1 mini-starburst ridge, a test for star formation efficiency models
• Dynamical population synthesis: Constructing the stellar single and binary contents of galactic field populations
• On the Power-Law Tail in the Mass Function of Protostellar Condensations and Stars
• Evidence of a non universal stellar Initial Mass Function. Insights from HST optical imaging of 6 Ultra Faint Dwarf Milky Way Satellites
• Stellar mass spectrum within massive collapsing clumps II. Thermodynamics and tidal forces of the first Larson core
• Characterizing the Brown Dwarf Formation Channels from the Initial Mass Function and Binary-star Dynamics
• Bondi-Hoyle-Littleton accretion and the upper mass stellar IMF
• Universal Scaling Relations in Scale-Free Structure Formation
• ALMA-IMF. V. Prestellar and protostellar core populations in the W43 cloud complex
• Mapping the core mass function to the initial mass function
• The Origin of the Stellar Mass Distribution and Multiplicity
• Numerical and semi-analytic core mass distributions in supersonic isothermal turbulence
• Turbulence, Coherence and Collapse: Three Phases for Core Evolution
• The bimodal initial mass function in the Orion Nebula Cloud
• Protostellar Feedback in Turbulent Fragmentation: Consequences for Stellar Clustering and Multiplicity
• ALMA-IMF XV: The core mass function in the high-mass star-formation regime
• The stellar IMF of Galactic clusters and its evolution
• The relation between accretion rates and the initial mass function in hydrodynamical simulations of star formation
• Early science with the Large Millimetre Telescope: An LMT/AzTEC 1.1 mm Survey of Dense Cores in the Monoceros R2 Giant Molecular Cloud
• Strong dependence of the physical properties of cores on spatial resolution in observations and simulations
• Star Formation in a Turbulent Framework: From Giant Molecular Clouds to Protostars
• The effect of the environment-dependent stellar initial mass function on the photometric properties of star-forming galaxies
• On the emergent System Mass Function: the contest between accretion and fragmentation
• Infall in massive clumps harboring bright infrared sources
• Fifty Years of IMF Variation: The Intermediate-Mass Stars
• The Impact of Early Massive Galaxy Formation on the Cosmic Microwave Background
• A stochastic and analytical model of hierarchical fragmentation: The fragmentation of gas structures into young stellar objects in the interstellar medium