Measuring the Clump Mass Function in the Age of SCUBA2, Herschel, and ALMA

Abstract

We use simulated images of star-forming regions to explore the effects of various image acquisition techniques on the derived clump mass function. In particular, we focus on the effects of finite image angular resolution, the presence of noise, and spatial filtering. We find that, even when the image has been so heavily degraded with added noise and lowered angular resolution that the clumps it contains clearly no longer correspond to pre-stellar cores, still the clump mass function is typically consistent with the stellar initial mass function within their mutual uncertainties. We explain this result by suggesting that noise, source blending, and spatial filtering all randomly perturb the clump masses, biasing the mass function toward a lognormal form whose high-mass end mimics a Salpeter power law. We argue that this is a consequence of the central limit theorem and that it strongly limits our ability to accurately measure the true mass function of the clumps. We support this conclusion by showing that the characteristic mass scale of the clump mass function, represented by the ``break mass'', scales as a simple function of the angular resolution of the image from which the clump mass function is derived. This strongly constrains our ability to use the clump mass function to derive a star formation efficiency. We discuss the potential and limitations of the current and next generation of instruments for measuring the clump mass function.

arXiv commentAccepted for publication in ApJ, 17 pages, 14 figures

References in corpus (22)

• Galactic Stellar and Substellar Initial Mass Function
• The Initial Mass Function of Stars: Evidence for Uniformity in Variable Systems
• SCUBA: A common-user submillimetre camera operating on the James Clerk Maxwell Telescope
• The Formation of a Star Cluster: Predicting the Properties of Stars and Brown Dwarfs
• Gasoline: An adaptable implementation of TreeSPH
• Structural Analysis of Molecular Clouds: Dendrograms
• The mass function of dense molecular cores and the origin of the IMF
• Star formation in clusters: a survey of compact mm-wave sources in the Serpens core
• The earliest phases of high-mass star formation: a 3 square degree millimeter continuum mapping of Cygnus X
• A Theory of the IMF for Star Formation in Molecular Clouds
• A SCUBA survey of the NGC 2068/2071 protoclusters
• The Mass-Size Relation from Clouds to Cores. II. Solar Neighborhood Clouds
• Numerical biases on IMF determinations created by binning
• The Perils of Clumpfind: The Mass Spectrum of Sub-structures in Molecular Clouds
• Large Area Mapping at 850 Microns. V. Analysis of the Clump Distribution in the Orion A South Molecular Cloud
• High Mass Star Formation I: The Mass Distribution of Submillimeter Clumps in NGC 7538
• Large Area Mapping at 850 Microns. IV. Analysis of the Clump Distribution in the Orion B South Molecular Cloud
• High Mass Star Formation. II. The Mass Function of Submillimeter Clumps in M17
• High Mass Star Formation. III. The Functional Form of the Submillimeter Clump Mass Function
• Removing sky contributions from SCUBA data
• The properties of SCUBA cores in the Perseus molecular cloud: the bias of clump-finding algorithms
• Cornell Caltech Atacama Telescope (CCAT): a 25 m aperture telescope above 5000 m altitude

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• Star Formation in the Milky Way and Nearby Galaxies
• The Magellanic Mopra Assessment (MAGMA). I. The Molecular Cloud Population of the Large Magellanic Cloud
• Properties of Hi-GAL clumps in the inner Galaxy]{The Hi-GAL compact source catalogue. I. The physical properties of the clumps in the inner Galaxy ($-71.0^{\circ }<\ell <67.0^{\circ }$)
• A sub-parsec resolution simulation of the Milky Way: Global structure of the ISM and properties of molecular clouds
• The Exciting Lives of Giant Molecular Clouds
• First results from the Herschel Gould Belt Survey in Taurus
• Luminosity Functions of Spitzer Identified Protostars in Nine Nearby Molecular Clouds
• ALMA Resolves 30 Doradus: Sub-parsec Molecular Cloud Structure Near the Closest Super-Star Cluster
• Probability Distribution Functions OF 12CO(J = 1-0) Brightness and Integrated Intensity in M51: The PAWS View
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• Search for starless clumps in the ATLASGAL survey
• Star formation towards the Scutum tangent region and the effects of Galactic environment
• Linking Dense Gas from the Milky Way to External Galaxies
• Observational constraints on star cluster formation theory - I. The mass-radius relation
• Galactic H2CO Densitometry I: Pilot survey of Ultracompact HII regions and methodology
• The Formation and Evolution of Small Star Clusters
• The Core Mass Function in the Orion Nebula Cluster Region: What Determines the Final Stellar Masses?
• The JCMT Gould Belt Survey: SCUBA-2 Data-Reduction Methods and Gaussian Source Recovery Analysis
• Mass distributions of stars and cores in young groups and clusters
• The TOP-SCOPE survey of PGCCs: PMO and SCUBA-2 observations of 64 PGCCs in the 2nd Galactic Quadrant
• Connecting the Dots: Analyzing Synthetic Observations of Star-Forming Clumps in Molecular Clouds
• The Clump Mass Function of the Dense Clouds in the Carina Nebula Complex
• Spatially associated clump populations in Rosette from CO and dust maps
• CO Core Candidates in the Gemini Molecular Cloud
• Extreme star formation in the Milky Way: Luminosity distributions of young stellar objects in W49A and W51
• Extreme giant molecular clouds in the luminous infrared galaxy NGC 3256
• Source clustering in the Hi-GAL survey determined using a minimum spanning tree method
• An ALMA archival study of the clump mass function in the Large Magellanic Cloud
• The Correlation of Dust and Gas Emission in Star-Forming Environments