A Core Mass Function Indistinguishable from the Salpeter Stellar Initial Mass Function Using 1000 au Resolution ALMA Observations

Abstract

We present the core mass function (CMF) of the massive star-forming clump G33.92+0.11 using 1.3 mm observations obtained with the Atacama Large Millimeter/submillimeter Array (ALMA). With a resolution of 1000 au, this is one of the highest resolution CMF measurements to date. The CMF is corrected by flux and number incompleteness to obtain a sample that is complete for gas masses $M\gtrsim 2.0M_{\odot }$. The resulting CMF is well represented by a power-law function ($dN/d\log M\propto M^{\Gamma }$), whose slope is determined using two different approaches: $i)$ by least-squares fitting of power-law functions to the flux- and number-corrected CMF, and $ii)$ by comparing the observed CMF to simulated samples with similar incompleteness. We provide a prescription to quantify and correct a flattening bias affecting the slope fits in the first approach, which is caused by small-sample or edge effects when the data is represented by either classical histograms or a kernel density estimate, respectively. The resulting slopes from both approaches are in good agreement each other, with $\Gamma =-1.11_{-0.11}^{+0.12}$ being our adopted value. Although this slope appears to be slightly flatter than the Salpeter slope $\Gamma =-1.35$ for the stellar initial mass function (IMF), we find from Monte Carlo simulations that the CMF in G33.92+0.11 is statistically indistinguishable from the Salpeter representation of the stellar IMF. Our results are consistent with the idea that the form of the IMF is inherited from the CMF, at least at high masses and when the latter is observed at high-enough resolution.

arXiv commentAccepted for publication in ApJ

References in corpus (41)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Power-law distributions in empirical data
• Binary companions of evolved stars in APOGEE DR14: Search method and catalog of ~5,000 companions
• The Stellar IMF from Turbulent Fragmentation
• Cold Dark Clouds: The Initial Conditions for Star Formation
• A Universal Stellar Initial Mass Function? A Critical Look at Variations
• Analytical theory for the initial mass function: CO clumps and prestellar cores
• Structural Analysis of Molecular Clouds: Dendrograms
• High-Mass Star and Massive Cluster Formation in the Milky Way
• On the Submillimeter Opacity of Protoplanetary Disks
• The mass function of dense molecular cores and the origin of the IMF
• Global Hierarchical Collapse In Molecular Clouds. Towards a Comprehensive Scenario
• An excess of massive stars in the local 30 Doradus starburst
• Stellar populations dominated by massive stars in dusty starburst galaxies across cosmic time
• The ALMA Survey of 70 $\mu$m dark High-mass clumps in Early Stages (ASHES). I. Pilot Survey: Clump Fragmentation
• Radiation-Hydrodynamic Simulations of the Formation of Orion-Like Star Clusters II. The Initial Mass Function from Winds, Turbulence, and Radiation
• Numerical biases on IMF determinations created by binning
• The unexpectedly large proportion of high-mass star-forming cores in a Galactic mini-starburst
• The Dawes Review 8: Measuring the Stellar Initial Mass Function
• The Perils of Clumpfind: The Mass Spectrum of Sub-structures in Molecular Clouds
• The efficiency of star formation in clustered and distributed regions
• ALMA resolves the spiraling accretion flow in the luminous OB cluster forming region G33.92+0.11
• Fragmentation and OB Star Formation in High-Mass Molecular Hub-Filament System
• The Core Mass Function Across Galactic Environments. II. Infrared Dark Cloud Clumps
• Bondi-Hoyle-Littleton accretion and the upper mass stellar IMF
• The Core Mass Function in the Massive Protocluster G286.21+0.17 revealed by ALMA
• Radiative transfer modelling of W33A MM1: 3-D structure and dynamics of a complex massive star forming region
• ALMA Observations of Massive Clouds in the Central Molecular Zone: Jeans Fragmentation and Cluster Formation
• Episodic accretion constrained by a rich cluster of outflows
• The Origin of the Stellar Mass Distribution and Multiplicity
• Thermal Jeans fragmentation within 1000 AU in OMC-1S
• Formation of the Hub-Filament System G33.92+0.11: Local Interplay between Gravity, Velocity, and Magnetic Field
• Physical Properties of the star-forming clusters in NGC 6334
• Star formation: statistical measure of the correlation between the prestellar core mass function and the stellar initial mass function
• Looking deep into the Rosette Nebula's heart: the (sub)stellar content of the massive young cluster NGC 2244
• Investigating fragmentation of gas structures in OB cluster-forming molecular clump G33.92+0.11 with 1000 AU resolution observations of ALMA
• System IMF of the 25 Ori Group from Planetary-Mass Objects to Intermediate/High-Mass Stars
• Strong dependence of the physical properties of cores on spatial resolution in observations and simulations
• The Core Mass Function in the Orion Nebula Cluster Region: What Determines the Final Stellar Masses?
• Dense cores and star formation in the giant molecular cloud Vela~C
• The Core Mass Function Across Galactic Environments. III. Massive Protoclusters