ALMA-IRDC: Dense gas mass distribution from cloud to core scales

Abstract

Infrared dark clouds (IRDCs) are potential hosts of the elusive early phases of high-mass star formation (HMSF). Here we conduct an in-depth analysis of the fragmentation properties of a sample of 10 IRDCs, which have been highlighted as some of the best candidates to study HMSF within the Milky Way. To do so, we have obtained a set of large mosaics covering these IRDCs with ALMA at band 3 (or 3mm). These observations have a high angular resolution (~3arcsec or ~0.05pc), and high continuum and spectral line sensitivity (~0.15mJy/beam and ~0.2K per 0.1km/s channel at the N2H+(1-0) transition). From the dust continuum emission, we identify 96 cores ranging from low- to high-mass (M = 3.4 to 50.9Msun) that are gravitationally bound (alpha_vir = 0.3 to 1.3) and which would require magnetic field strengths of B = 0.3 to 1.0mG to be in virial equilibrium. We combine these results with a homogenised catalogue of literature cores to recover the hierarchical structure within these clouds over four orders of magnitude in spatial scale (0.01pc to 10pc). Using supplementary observations at an even higher angular resolution, we find that the smallest fragments (<0.02pc) within this hierarchy do not currently have the mass and/or the density required to form high-mass stars. Nonetheless, the new ALMA observations presented in this paper have facilitated the identification of 19 (6 quiescent and 13 star-forming) cores that retain >16Msun without further fragmentation. These high-mass cores contain trans-sonic non-thermal motions, are kinematically sub-virial, and require moderate magnetic field strengths for support against collapse. The identification of these potential sites of high-mass star formation represents a key step in allowing us to test the predictions from high-mass star and cluster formation theories.

arXiv comment21(+6 in appendix) pages, 12(+3) figures, 3(+3) tables. Machine-readable versions of Table A1, A2 and A3 are available online. Accepted for publication in MNRAS

References in corpus (101)

• Theory of Star Formation
• Toward Understanding Massive Star Formation
• SparsePak: A Formatted Fiber Field Unit for The WIYN Telescope Bench Spectrograph. I. Design, Construction, and Calibration
• The Formation of Massive Stars from Turbulent Cores
• The Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey
• MAMBO Mapping of Spitzer c2d Small Clouds and Cores
• Dense Cores in Dark Clouds. XIV. N2H+(1-0) maps of dense cloud cores
• Competitive accretion in embedded stellar cluster
• Structural Analysis of Molecular Clouds: Dendrograms
• Infrared Dark Clouds: precursors to star clusters
• Probing the evolution of molecular cloud structure: From quiescence to birth
• Cores, filaments, and bundles: hierarchical core formation in the L1495/B213 Taurus region
• Massive star formation: Nurture, not nature
• Global collapse of molecular clouds as a formation mechanism for the most massive stars
• Global Hierarchical Collapse In Molecular Clouds. Towards a Comprehensive Scenario
• A Minimum Column Density of 1 g cm^-2 for Massive Star Formation
• The lifecycle of molecular clouds in nearby star-forming disc galaxies
• Ammonia in Infrared Dark Clouds
• Hi-GAL, the Herschel infrared Galactic Plane Survey: photometric maps and compact source catalogues. First data release for Inner Milky Way: +68°> l > -70°
• Fast and inefficient star formation due to short-lived molecular clouds and rapid feedback
• How Many Infrared Dark Clouds can form Massive Stars and Clusters?
• Molecular gas kinematics within the central 250 pc of the Milky Way
• Magnetic Fields in High-Mass Infrared Dark Clouds
• A Catalog of MSX Infrared Dark Cloud Candidates
• The anatomy of the Orion B Giant Molecular Cloud: A local template for studies of nearby galaxies
• Dense core formation by fragmentation of velocity-coherent filaments in L1517
• 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 ($-71.0^{\circ }<\ell <67.0^{\circ }$)
• Fragmentation of Molecular Clumps and Formation of Protocluster
• Molecular ions in L1544. I. Kinematics
• Mid-Infrared Extinction Mapping of Infrared Dark Clouds II. The Structure of Massive Starless Cores and Clumps
• The Origin of Massive Stars: The Inertial-Inflow Model
• Characterizing Precursors to Stellar Clusters with Herschel
• The Dynamics of Massive Starless Cores with ALMA
• Probing the initial conditions of high-mass star formation. II. Fragmentation, stability, and chemistry
• High-dynamic-range extinction mapping of infrared dark clouds: Dependence of density variance with sonic Mach number in molecular clouds
• Multi-temperature mapping of dust structures throughout the Galactic Plane using the PPMAP tool with Herschel Hi-GAL data
• The Mass-Size Relation from Clouds to Cores. II. Solar Neighborhood Clouds
• The dynamical properties of dense filaments in the infrared dark cloud G035.39-00.33
• G0.253+0.016: a molecular cloud progenitor of an Arches-like cluster
• Mid-Infrared Extinction Mapping of Infrared Dark Clouds: Probing the Initial Conditions for Massive Stars and Star Clusters
• A Massive Prestellar Clump Hosting no High-Mass Cores
• The Bolocam Galactic Plane Survey. VII. Characterizing the Properties of Massive Star-Forming Regions
• On the frequency of N2H+ and N2D+
• Molecular Line Emission as a Tool for Galaxy Observations (LEGO). I. HCN as a tracer of moderate gas densities in molecular clouds and galaxies
• Gravity or turbulence? -III. Evidence of pure thermal Jeans fragmentation at ~0.1 pc scale
• The Herschel view of massive star formation in G035.39--00.33: Dense and cold filament of W48 undergoing a mini-starburst
• The Galactic Center Cloud G0.253+0.016: A Massive Dense Cloud with low Star Formation Potential
• 'The Brick' is not a brick: A comprehensive study of the structure and dynamics of the Central Molecular Zone cloud G0.253+0.016
• Early stages of cluster formation: fragmentation of massive dense cores down to ~1000 AU
• Fragmentation of massive dense cores down to ~1000 AU: Relation between fragmentation and density structure
• The Musca cloud: A 6 pc-long velocity-coherent, sonic filament
• AUTO-MULTITHRESH: A General Purpose Automasking Algorithm
• Mapping Large-Scale CO Depletion in a Filamentary Infrared Dark Cloud
• Complex, Quiescent Kinematics in a Highly Filamentary Infrared Dark Cloud
• Mapping the column density and dust temperature structure of IRDCs with Herschel
• The Mass-Size Relation from Clouds to Cores. I. A new Probe of Structure in Molecular Clouds
• Autonomous Gaussian Decomposition
• GaussPy+: A fully automated Gaussian decomposition package for emission line spectra
• Very Large Array Observations of Ammonia in Infrared-Dark Clouds I: Column Density and Temperature Structure
• Opacity broadening and interpretation of suprathermal CO linewidths: Macroscopic Turbulence and Tangled Molecular Clouds
• A holistic perspective on the dynamics of G035.39-00.33: the interplay between gas and magnetic fields
• Gravity, Magnetic Field, and Turbulence: Relative Importance and Impact on Fragmentation in the Infrared Dark Cloud G34.43+00.24
• The Impact of Feedback During Massive Star Formation by Core Accretion
• A statistical study of the mass and density structure of Infrared Dark Clouds
• A large catalogue of molecular clouds with accurate distances within 4 kpc of the Galactic disk
• Investigating the structure and fragmentation of a highly filamentary IRDC
• Unveiling the Early-Stage Anatomy of a Protocluster Hub with ALMA
• Which feedback mechanisms dominate in the high-pressure environment of the Central Molecular Zone?
• Gas Kinematics and Excitation in the Filamentary IRDC G035.39-00.33
• Properties of dense cores in clustered massive star-forming regions at high angular resolution
• Physical properties of Southern infrared dark clouds
• The Deuterium Fraction in Massive Starless Cores and Dynamical Implications
• The Core Mass Function Across Galactic Environments. II. Infrared Dark Cloud Clumps
• On the structure of molecular clouds
• A Hunt for Massive Starless Cores
• The Core Mass Function in the Massive Protocluster G286.21+0.17 revealed by ALMA
• Magnetic fields in the infrared dark cloud G34.43+0.24
• LEGO II: A 3 mm molecular line study covering 100 pc of one of the most actively star-forming portions within the Milky Way Disc
• Very Large Array Observations of Ammonia in Infrared-Dark Clouds II: Internal Kinematics
• The Mass-Size Relation and the Constancy of GMC Surface Densities in the Milky Way
• Widespread Molecular Outflows in the Infrared Dark Cloud G28.37+0.07: Indications of Orthogonal Outflow-Filament Alignment
• The Darkest Shadows: Deep Mid-Infrared Extinction Mapping of a Massive Protocluster
• Outflow detection in a 70 $\mu$m dark high-mass core
• Are Infrared Dark Clouds Really Quiescent?
• Physical Properties of the star-forming clusters in NGC 6334
• Magnetic fields in the early stages of massive star formation as revealed by ALMA
• Temperature structure and kinematics of the IRDC G035.39-00.33
• CN Zeeman and dust polarization in a high-mass cold clump
• Widespread deuteration across the IRDC G035.39-00.33
• Physical Conditions of the Earliest Phases of Massive Star Formation: Single-Dish and Interferometric Observations of Ammonia and CCS in Infrared Dark Clouds
• The fragmentation properties of massive protocluster gas clumps: an ALMA study
• The Distribution of Mass Surface Densities in a High-Mass Protocluster
• Interstellar Plunging Waves: ALMA resolves the physical structure of non-stationary MHD shocks
• The accretion history of high-mass stars: An ArTéMiS pilot study of Infrared Dark Clouds
• Widespread SiO and CH3OH emission in Filamentary Infrared Dark Clouds
• GASTON: Galactic Star Formation with NIKA2. Evidence for the mass growth of star-forming clumps
• A multi-wavelength observation and investigation of six infrared dark clouds
• Similar complex kinematics within two massive, filamentary infrared dark clouds
• Evidence that widespread star formation may be underway in G0.253+016, "The Brick"
• The SOFIA Massive (SOMA) Star Formation Survey. III. From Intermediate- to High-Mass Protostars
• Core Emergence in a Massive Infrared Dark Cloud: A Comparison Between Mid-IR Extinction and 1.3 mm Emission

Cited by in corpus (21)

• The ALMA Survey of 70 $\mu$m Dark High-mass Clumps in Early Stages (ASHES). IX. Physical Properties and Spatial Distribution of Cores in IRDCs
• An ALMA study of hub-filament systems I. On the clump mass concentration within the most massive cores
• The ALMA Survey of 70 μm Dark High-mass Clumps in Early Stages (ASHES). VIII. Dynamics of Embedded Dense Cores
• The ALMA Survey of 70 $\mu$m Dark High-mass Clumps in Early Stages (ASHES). IV. Star formation signatures in G023.477
• Identification of prestellar cores in high-mass star forming clumps via ${\mathrm{H}}_2{\mathrm{D}}^{+}$ observations with ALMA
• Mother of Dragons: A Massive, quiescent core in the dragon cloud (IRDC G028.37+00.07)
• ATOMS: ALMA Three-millimeter Observations of Massive Star-forming regions -- XII: Fragmentation and multi-scale gas kinematics in protoclusters G12.42+0.50 and G19.88-0.53
• The dynamic centres of infrared-dark clouds and the formation of cores
• Emergence of high-mass stars in complex fiber networks (EMERGE). I. Early ALMA Survey: observations and massive data reduction
• Fragmentation of the High-mass "Starless'' Core G10.21-0.31: a Coherent Evolutionary Picture for Star Formation
• Deuterium Fractionation across the Infrared Dark Cloud G034.77-00.55 interacting with the Supernova Remnant W44
• Emergence of high-mass stars in complex fiber networks (EMERGE) V. From filaments to spheroids: the origin of the hub-filament systems
• CMZoom III: Spectral Line Data Release
• Interaction between the Supernova Remnant W44 and the Infrared Dark Cloud G034.77-00.55: shock induced star formation?
• Emergence of high-mass stars in complex fiber networks (EMERGE) III. Fiber networks in Orion
• Line emission from filaments in molecular clouds
• Synthetic ngVLA line observations of a massive star-forming cloud
• Chemical complexity in star formation induced by stellar feedback: cores shock-formed by the supernova remnant W44
• Chemistry of Dark Molecular Clouds
• ATOMS: ALMA Three-millimeter Observations of Massive Star-forming regions -- V. Hierarchical fragmentation and gas dynamics in IRDC G034.43+00.24
• Molecular Clouds at the Edge of the Galaxy II. Physical properties and scaling relations