Evolutionary Description of Giant Molecular Cloud Mass Functions on Galactic Disks

Abstract

Recent radio observations show that the giant molecular cloud (GMC) mass functions noticeably vary across galactic disks. High-resolution magnetohydrodynamics simulations show that multiple episodes of compression are required for creating a molecular cloud in the magnetized interstellar medium. In this article, we formulate the evolution equation for the GMC mass function to reproduce the observed profiles, for which multiple compression are driven by the network of expanding shells due to HII regions and supernova remnants. We introduce the cloud-cloud collision (CCC) terms in the evolution equation in contrast to the previous work (Inutsuka et al. 2015). The computed time evolution suggests that the GMC mass function slope is governed by the ratio of GMC formation timescale to its dispersal timescale, and that the CCC effect is limited only in the massive-end of the mass function. In addition, we identify a gas resurrection channel that allows the gas dispersed by massive stars to regenerate GMC populations or to accrete onto the pre-existing GMCs. Our results show that almost all of the dispersed gas contribute to the mass growth of pre-existing GMCs in arm regions whereas less than 60 per cent in inter-arm regions. Our results also predict that GMC mass functions have a single power-law exponent in the mass range < 10^5.5 Msun (where Msun represents the solar mass), which is well characterized by GMC self-growth and dispersal timescales. Measurement of the GMC mass function slope provides a powerful method to constrain those GMC timescales and the gas resurrecting factor in various environment across galactic disks.

18 pages, 15 figures, 3 tables, accepted to ApJ; A typo in the title of the version 1 is corrected and replaced as the version 2

References in corpus (57)

• Cosmic Star Formation History
• Star Formation in the Milky Way and Nearby Galaxies
• From filamentary clouds to prestellar cores to the stellar IMF: Initial highlights from the Herschel Gould Belt survey
• The Neutral Atomic Phases of the ISM in the Galaxy
• High molecular gas fractions in normal massive star forming galaxies in the young Universe
• Clouds, filaments and protostars: the Herschel Hi-GAL Milky Way
• Characterizing interstellar filaments with Herschel in IC5146
• A Molecular Star Formation Law in the Atomic Gas Dominated Regime in Nearby Galaxies
• An Origin of Supersonic Motions in Interstellar Clouds
• Thermal condensation in a turbulent atomic hydrogen flow
• The Equilibrium State of Molecular Regions in the Outer Galaxy
• The Second Survey of the Molecular Clouds in the Large Magellanic Cloud by NANTEN. II. Star Formation
• Star Formation in Disk Galaxies. I. Formation and Evolution of Giant Molecular Clouds via Gravitational Instability and Cloud Collisions
• The PdBI Arcsecond Whirlpool Survey (PAWS): Environmental Dependence of Giant Molecular Cloud Properties in M51
• The Formation and Destruction of Molecular Clouds and Galactic Star Formation
• The PdBI Arcsecond Whirlpool Survey (PAWS). I. A Cloud-Scale/Multi-Wavelength View of the Interstellar Medium in a Grand-Design Spiral Galaxy
• Molecular cloud evolution. I. Molecular cloud and thin CNM sheet formation
• Giant Molecular Clouds in M33 - I. BIMA All Disk Survey
• Filaments and ridges in Vela C revealed by Herschel: from low-mass to high-mass star-forming sites
• Molecular Hydrogen in the FUSE Translucent Lines of Sight: The Full Sample
• The Birth of Molecular Clouds: Formation of Atomic Precursors in Colliding Flows
• Giant Molecular Clouds in M33 -- II. High Resolution Observations
• Formation of Structure in Molecular Clouds: A Case Study
• A Uniform Catalog of Molecular Clouds in the Milky Way
• A census of dense cores in the Aquila cloud complex: SPIRE/PACS observations from the Herschel Gould Belt survey
• The Exciting Lives of Giant Molecular Clouds
• The Plateau de Bure + 30m Arcsecond Whirlpool Survey reveals a thick disk of diffuse molecular gas in the M51 galaxy
• Dynamically Driven Evolution of the Interstellar Medium in M51
• Dynamical Expansion of Ionization and Dissociation Front around a Massive Star. II. On the Generality of Triggered Star Formation
• Molecular Clouds Toward the Super Star Cluster NGC3603; Possible Evidence for a Cloud-Cloud Collision in Triggering the Cluster Formation
• Formation of Turbulent and Magnetized Molecular Clouds via Accretion Flows of HI Clouds
• Two-Fluid MHD Simulations of Converging HI Flows in the Interstellar Medium. I: Methodology and Basic Results
• High Resolution Molecular Gas Maps of M33
• Giant Molecular Clouds in the Local Group Galaxy M33
• The frequency and nature of `cloud-cloud collisions' in galaxies
• Cloud-cloud collision as a trigger of the high-mass star formation; a molecular line study in RCW120
• Evolution of OH and CO-dark Molecular Gas Fraction Across a Molecular Cloud Boundary In Taurus
• The two molecular clouds in RCW 38; evidence for formation of the youngest super star cluster in the Milky Way triggered by cloud-cloud collision
• Two-Fluid MHD Simulations of Converging Hi Flows in the Interstellar Medium. II: Are Molecular Clouds Generated Directly from Warm Neutral Medium?
• On the structure of the turbulent interstellar atomic hydrogen. I- Physical characteristics
• The PdBI Arcsecond Whirlpool Survey (PAWS): Multi-phase cold gas kinematic of M51
• Short GMC lifetimes: an observational estimate with the PdBI Arcsecond Whirlpool Survey (PAWS)
• Effects of Magnetic Field Strength and Orientation on Molecular Cloud Formation
• Optically thick HI dominant in the local interstellar medium; an alternative interpretation to "dark gas"
• Physical Conditions in Molecular Clouds in the Arm and Interarm Regions of M51
• Evidence For Cloud-Cloud Collision and Parsec-Scale Stellar Feedback Within the L1641-N Region
• Giant Molecular Clouds in the Early-Type Galaxy NGC4526
• H2 distribution during formation of multiphase molecular clouds
• CO(1-0) imaging of M51 with CARMA and NRO45
• A possible link between the power spectrum of interstellar filaments and the origin of the prestellar core mass function
• Giant Molecular Clouds are More Concentrated to Spiral Arms than Smaller Clouds
• The Scaleheight of Giant Molecular Clouds is Less than that of Smaller Clouds
• A statistical study of giant molecular clouds traced by ${}^{13}$CO, C${}^{18}$O, CS, and CH${}_3$OH in the disk of NGC 1068 based on ALMA observations
• Physical properties of CO-dark molecular gas traced by C${}^{+}$
• Gravitational Fragmentation of Expanding Shells. I. Linear Analysis
• Detection of Dense Molecular Gas in Inter-Arm Spurs in M51
• Gravitational Fragmentation of Expanding Shells. II. Three-dimensional Simulations

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• Stochastic modelling of star-formation histories II: star-formation variability from molecular clouds and gas inflow
• The molecular cloud lifecycle
• The ALMA view of GMCs in NGC 300: Physical Properties and Scaling Relations at 10 pc Resolution
• Momentum feedback from marginally-resolved HII regions in isolated disc galaxies
• ALMA ${}^{12}$CO (J=1--0) imaging of the nearby galaxy M83: Variations in the efficiency of star formation in giant molecular clouds
• FOREST Unbiased Galactic plane Imaging survey with the Nobeyama 45-m telescope (FUGIN) : Molecular clouds toward W33 ; possible evidence for a cloud-cloud collision triggering O star formation
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• The Galactic Census of High- and Medium-mass Protostars. IV. Molecular Clump Radiative Transfer, Mass Distributions, Kinematics, and Dynamical Evolution
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• A Morphological Classification of 18190 Molecular Clouds Identified in ${}^{12}$CO Data from the MWISP Survey
• Velocity structure of the 50 pc-long NGC 6334 filamentary cloud: Hints of multiple compressions and their impact on the cloud properties?
• Properties of giant molecular clouds in the strongly barred galaxy NGC1300
• The Early Stage of Molecular Cloud Formation by Compression of Two-phase Atomic Gases
• An ALMA Glimpse of Dense Molecular Filaments Associated with High-mass Protostellar Systems in the Large Magellanic Cloud
• The changing GMC population in galaxy interactions
• ALMA Resolves Giant Molecular Clouds in a Tidal Dwarf Galaxy
• WISDOM Project XII. Clump properties and turbulence regulated by clump-clump collisions in the dwarf galaxy NGC404
• An Unbiased CO Survey Toward the Northern Region of the Small Magellanic Cloud with the Atacama Compact Array. II. CO Cloud Catalog
• Building the molecular cloud population: the role of cloud mergers
• Rise and fall of molecular clouds across the M33 disk
• ACA CO($J=2-1$) Mapping of the Nearest Spiral Galaxy M33. I. Initial Results and Identification of Molecular Clouds
• ALMA Observations of Giant Molecular Clouds in M33 III: Spatially Resolved Features of the Star-Formation Inactive Million-solar-mass Cloud
• Cloud-cloud collisions triggering star formation in galaxy simulations
• Submillimeter Array CO(2-1) Imaging of the NGC 6946 Giant Molecular Clouds
• A Giant Molecular Cloud Catalog in the Molecular Disk of the Elliptical Galaxy NGC 5128 (Centaurus A)
• Giant molecular clouds and their Type classification in M74: Toward understanding star formation and cloud evolution
• ACA CO(J=2-1) Mapping of the Nearest Spiral Galaxy M33. II. Exploring the Evolution of Giant Molecular Clouds
• A fast tree algorithm for multi-component coagulation equation
• Luminosity functions and IMF variations from large samples of HII regions and molecular clouds
• Molecular cloud matching in CO and dust in M33 II. Physical properties of giant molecular clouds