Identification of molecular clouds in emission maps: a comparison between methods in the \ce{^{13}CO}/\ce{C^{18}O} ($J=3-2$) Heterodyne Inner Milky Way Plane Survey

Abstract

The growing range of automated algorithms for the identification of molecular clouds and clumps in large observational datasets has prompted the need for the direct comparison of these procedures. However, these methods are complex and testing for biases is often problematic: only a few of them have been applied to the same data set or calibrated against a common standard. We compare the Fellwalker method, a widely used watershed algorithm, to the more recent Spectral Clustering for Interstellar Molecular Emission Segmentation (SCIMES). SCIMES overcomes sensitivity and resolution biases that plague many friends-of-friends algorithms by recasting cloud segmentation as a clustering problem. Considering the \ce{^{13}CO}/\ce{C^{18}O} ($J=3-2$) Heterodyne Inner Milky Way Plane Survey (CHIMPS) and the CO High-Resolution Survey (COHRS), we investigate how these two different approaches influence the final cloud decomposition. Although the two methods produce largely similar statistical results over the CHIMPS dataset, FW appears prone to over-segmentation, especially in crowded fields where gas envelopes around dense cores are identified as adjacent, distinct objects. FW catalogue also includes a number of fragmented clouds that appear as different objects in a line-of-sight projection. In addition, cross-correlating the physical properties of individual sources between catalogues is complicated by different definitions, numerical implementations, and design choices within each method, which make it very difficult to establish a one-to-one correspondence between the sources.

arXiv commentaccepted MNRAS

References in corpus (64)

• Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds
• Astropy: A Community Python Package for Astronomy
• Binary companions of evolved stars in APOGEE DR14: Search method and catalog of ~5,000 companions
• The Milky Way in Molecular Clouds: A New Complete CO Survey
• The Star Formation Law in Nearby Galaxies on Sub-Kpc Scales
• Trigonometric Parallaxes of High Mass Star Forming Regions: the Structure and Kinematics of the Milky Way
• Cold Dark Clouds: The Initial Conditions for Star Formation
• The Molecular Interstellar Medium in Ultraluminous Infrared Galaxies
• The Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey
• Structural Analysis of Molecular Clouds: Dendrograms
• Rapid Formation of Molecular Clouds and Stars in the Solar Neighborhood
• A Molecular Star Formation Law in the Atomic Gas Dominated Regime in Nearby Galaxies
• The Universality of Turbulence in Galactic Molecular Clouds
• Velocity Modification of HI Power Spectrum
• Physical properties of molecular clouds for the entire Milky Way disk
• ATLASGAL --- properties of a complete sample of Galactic clumps
• Physical Properties and Galactic Distribution of Molecular Clouds identified in the Galactic Ring Survey
• Bias-free Measurement of Giant Molecular Cloud Properties
• Low Virial Parameters in Molecular Clouds: Implications for High Mass Star Formation and Magnetic Fields
• A Parallax-based Distance Estimator for Spiral Arm Sources
• Hi-GAL, the Herschel infrared Galactic Plane Survey: photometric maps and compact source catalogues. First data release for Inner Milky Way: +68°> l > -70°
• The Magellanic Mopra Assessment (MAGMA). I. The Molecular Cloud Population of the Large Magellanic Cloud
• The PdBI Arcsecond Whirlpool Survey (PAWS): Environmental Dependence of Giant Molecular Cloud Properties in M51
• Kinematic Distances to Molecular Clouds identified in the Galactic Ring Survey
• The Nature of the Dense Core Population in the Pipe Nebula: Thermal Cores Under Pressure
• HARP/ACSIS: A submillimetre spectral imaging system on the James Clerk Maxwell Telescope
• Clouds as Turbulent Density Fluctuations. Implications for pressure confinement and spectral line data interpretation
• FOREST Unbiased Galactic plane Imaging survey with the Nobeyama 45-m telescope (FUGIN) I: Project Overview and Initial Results
• A Comparative Study of Giant Molecular Clouds in M51, M33 and the Large Magellanic Cloud
• A Uniform Catalog of Molecular Clouds in the Milky Way
• ATLASGAL --- Environments of 6.7\,GHz methanol masers
• Numerical biases on IMF determinations created by binning
• FellWalker - a Clump Identification Algorithm
• The Perils of Clumpfind: The Mass Spectrum of Sub-structures in Molecular Clouds
• SEDIGISM: Structure, excitation, and dynamics of the inner Galactic interstellar medium
• A Fractal Origin for the Mass Spectrum of Interstellar Clouds: II. Cloud Models and Power Law Slopes
• CHIMPS: the ${}^{13}$CO/C${}^{18}$O (J=3-2) Heterodyne Inner Milky Way Plane Survey
• Turbulence sets the initial conditions for star formation in high-pressure environments
• Graph-based interpretation of the Molecular Interstellar Medium Segmentation
• The Fractal Dimension of Projected Clouds
• ATLASGAL - Kinematic distances and the dense gas mass distribution of the inner Galaxy
• A method for reconstructing the variance of a 3D physical field from 2D observations: Application to turbulence in the ISM
• Spiral shocks, triggering of star formation and the velocity dispersion in Giant Molecular Clouds
• The Spectral Correlation Function -- A New Tool for Analyzing Spectral-Line Maps
• The integrated properties of the molecular clouds from the JCMT CO(3-2) High Resolution Survey
• Dust and gas power-spectrum in M33 (HERM33ES)
• The JCMT Plane Survey: early results from the l = 30 degree field
• CHIMPS: Physical properties of molecular clumps across the inner Galaxy
• The JCMT Plane Survey: First complete data release - emission maps and compact source catalogue
• The Mass-Size Relation and the Constancy of GMC Surface Densities in the Milky Way
• The Spectral Correlation Function of Molecular Clouds: A Statistical Test for Theoretical Models
• Star formation scales and efficiency in Galactic spiral arms
• The Multi-phase Turbulence Density Power Spectra in the Perseus Molecular Cloud
• An Observational Method to Measure the Relative Fractions of Solenoidal and Compressible Modes in Interstellar Clouds
• Assessing the Performance of Molecular Gas Clump Identification Algorithms
• Time variation of radial gradients in the galactic disk: electron temperatures and abundances
• A possible observational bias in the estimation of the virial parameter in virialized clumps
• Extended warm and dense gas towards W49A: starburst conditions in our Galaxy?
• Physical and chemical differentiation of the luminous star-forming region W49A - Results from the JCMT Spectral Legacy Survey
• G-virial: Gravity-based structure analysis of molecular clouds
• Structure analysis of simulated molecular clouds with the Delta-variance
• Extreme star formation in the Milky Way: Luminosity distributions of young stellar objects in W49A and W51
• The CARMA-NRO Orion Survey: Statistical Signatures of Feedback in the Orion A Molecular Cloud
• An Observational Perspective of Low-Mass Dense Cores I: Internal Physical and Chemical Properties

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