Bird's eye view of molecular clouds in the Milky Way: I. Column density and star formation from sub-pc to kpc scales

Abstract

Describing how the properties of the interstellar medium combine across size-scales is crucial for understanding star formation scaling laws and connecting Galactic and extragalactic data of molecular clouds. We describe how the statistical structure of clouds, and its connection to star formation, changes from sub-parsec to kiloparsec scales in a complete region within the Milky Way disk. We build a census of molecular clouds within 2 kpc from the Sun using literature. We examine the dust-based column density probability distributions (N-PDFs) of the clouds and their relation to star formation traced by young stellar objects (YSOs). We then examine our survey region from the outside, within apertures of varying sizes, and describe how the N-PDFs and their relation to star formation changes with the size-scale. The N-PDFs of the clouds are not well described by any single simple model; use of any single model may bias the interpretation of the N-PDFs. The top-heaviness of the N-PDFs correlates with star formation activity, and the correlation changes with Galactic environment (spiral-/inter-arm regions). We find that the density contrast of clouds may be more intimately linked to star formation than the dense gas mass fraction. The aperture-averaged N-PDFs vary with the size-scale and are more top-heavy for larger apertures. The top-heaviness of the aperture N-PDFs correlates with star formation activity up to roughly 0.5 kpc size-scale, depending on the environment. Our results suggest that the relations between cloud structure and star formation are environment specific and best captured by relative quantities (e.g., the density contrast). Finally, we show how the density structures of individual clouds give rise to a kpc-scale Kennicutt-Schmidt relationship as a combination of sampling effects and blending of different galactic environments.

19 pages and 19 figures in main text. Accepted for publication in A&A

References in corpus (43)

• The UKIRT Infrared Deep Sky Survey (UKIDSS)
• The UKIDSS Galactic Plane Survey
• The Density Probability Distribution in Compressible Isothermal Turbulence: Solenoidal versus Compressive Forcing
• On the Star Formation Efficiency of Turbulent Magnetized Clouds
• Physical properties of molecular clouds for the entire Milky Way disk
• Gaia-2MASS 3D maps of Galactic interstellar dust within 3 kpc
• What determines the density structure of molecular clouds ? A case study of Orion B with Herschel
• A Large Catalog of Accurate Distances to Local Molecular Clouds: The Gaia DR2 Edition
• A Compendium of Distances to Molecular Clouds in the Star Formation Handbook
• 2MASS wide field extinction maps - I. The Pipe nebula
• The anatomy of the Orion B Giant Molecular Cloud: A local template for studies of nearby galaxies
• Multi-temperature mapping of dust structures throughout the Galactic Plane using the PPMAP tool with Herschel Hi-GAL data
• Molecular Gas Properties on Cloud Scales Across the Local Star-forming Galaxy Population
• Cloud Scale ISM Structure and Star Formation in M51
• Unfolding the Laws of Star Formation: The Density Distribution of Molecular Clouds
• NICEST, a near-infrared color excess method tailored for small-scale structures
• Comparing Numerical Methods for Isothermal Magnetized Supersonic Turbulence
• Evolution of column density distributions within Orion~A
• Molecular clouds have power-law probability distribution functions
• Understanding star formation in molecular clouds I. Effects of line-of-sight contamination on the column density structure
• A Portrait of Cold Gas in Galaxies at 60pc Resolution and a Simple Method to Test Hypotheses That Link Small-Scale ISM Structure to Galaxy-Scale Processes
• The dynamical evolution of molecular clouds near the Galactic Centre - II. Spatial structure and kinematics of simulated clouds
• Herschel's view of the large-scale structure in the Chamaeleon dark clouds
• The shapes of column density PDFs - The importance of the last closed contour
• Dense gas is not enough: environmental variations in the star formation efficiency of dense molecular gas at 100pc scales in M51
• Star-Gas Surface Density Correlations in Twelve Nearby Molecular Clouds I: Data Collection and Star-Sampled Analysis
• Chandra Observations of the Eagle Nebula. I. Embedded Young Stellar Objects near the Pillars of Creation
• Massive Clumps in the NGC 6334 Star Forming Region
• HP2 survey: III The California Molecular Cloud--A Sleeping Giant Revisited
• The JCMT Gould Belt Survey: Dense Core Clusters in Orion A
• A Spitzer View of Mon OB1 East/NGC 2264
• A model for the onset of self-gravitation and star formation in molecular gas governed by galactic forces: II. the bottleneck to collapse set by cloud-environment decoupling
• Mapping the three-dimensional dust extinction toward the supernova remnant S147 - the S147 dust cloud
• The JCMT Gould Belt Survey: A First Look at IC 5146
• On the gravitational content of molecular clouds and their cores
• Detection of Star Formation in the Unusually Cold Giant Molecular Cloud G216
• Power-law tails in probability density functions of molecular cloud column density
• Relationship between turbulence energy and density variance in the Solar neighbourhood molecular clouds
• Structural Variation of Molecular Gas in the Sagittarius Arm and Inter-Arm Regions
• Internal Structures of Molecular Clouds in the LMC Revealed by ALMA
• Deep PSF photometric catalog of the VVV survey data
• Young Stars near Cometary Globule CG 30 in the Tumultuous Gum Nebula
• Multiwavelength study of the G345.5+1.5 region

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• PDFchem: A new fast method to determine ISM properties and infer environmental parameters using probability distributions
• The warm-hot circumgalactic medium of the Milky Way as seen by eROSITA
• Gas Column Density Distribution of Molecular Clouds in the Third Quadrant of the Milky Way
• Distances to nearby molecular clouds traced by young stars
• Bird's eye view of molecular clouds in the Milky Way: II. Cloud kinematics from sub-pc to kpc scales
• Magnetic Field of Molecular Gas Measured with the Velocity Gradient Technique I. Orion A
• Metallicity dependence of the CO-to-H${}_2$ and the [CI]-to-H${}_2$ conversion factors in galaxies
• 25 years of XMM-Newton observations of the Sgr A complex: 3D distribution and internal structure of the clouds
• Reconciling extragalactic star formation efficiencies with theory: insights from PHANGS
• Probing the Global Dust Properties and Cluster Formation Potential of the Giant Molecular Cloud G148.24+00.41
• A Three-Dimensional Analytical Model of the Interstellar Extinction within the Nearest Kiloparsec
• Molecular Cloud Matching in CO and Dust in M33 I. High-Resolution Hydrogen Column Density Maps from Herschel
• Discovery of the Goat Horn complex: a $\sim 1000$ deg${}^2$ diffuse X-ray source connected to radio loop XII
• The effect of viewing angle on the Kennicutt-Schmidt relation of the local molecular clouds
• Chemical templates of the Central Molecular Zone. Shock and protostellar object signatures under Galactic Center conditions
• Sub-kpc scale gas density histogram of the Galactic molecular gas: a new statistical method to characterise galactic-scale gas structures
• On volume density and star formation in nearby molecular clouds