WISDOM Project XII. Clump properties and turbulence regulated by clump-clump collisions in the dwarf galaxy NGC404

Abstract

We present a study of molecular structures (clumps and clouds) in the dwarf galaxy NGC 404 using high-resolution (0.86x0.51 pc^2) Atacama Large Millimeter/sub-millimeter Array ^{12}CO(2-1) observations. We find two distinct regions in NGC 404: a gravitationally-stable central region (Toomre parameter Q=3-30) and a gravitationally-unstable molecular ring (Q<=1). The molecular structures in the central region have a steeper size -- linewidth relation and larger virial parameters than those in the molecular ring, suggesting gas is more turbulent in the former. In the molecular ring, clumps exhibit a shallower mass -- size relation and larger virial parameters than clouds, implying density structures and dynamics are regulated by different physical mechanisms at different spatial scales. We construct an analytical model of clump-clump collisions to explain the results in the molecular ring. We propose that clump-clump collisions are driven by gravitational instabilities coupled with galactic shear, that lead to a population of clumps whose accumulation lengths (i.e. average separations) are approximately equal to their tidal radii. Our model-predicted clump masses and sizes (and mass -- size relation) and turbulence energy injection rates (and size -- linewidth relation) match the observations in the molecular ring very well, suggesting clump-clump collisions is the main mechanism regulating clump properties and gas turbulence in that region. As expected, our collision model does not apply to the central region, where turbulence is likely driven by clump migration.

Accepted for publication on MNRAS

References in corpus (43)

• Theory of Star Formation
• Cold streams in early massive hot haloes as the main mode of galaxy formation
• Formation of Massive Galaxies at High Redshift: Cold Streams, Clumpy Disks and Compact Spheroids
• From rings to bulges: evidence for rapid secular galaxy evolution at z~2 from integral field spectroscopy in the SINS survey
• The Role of Pressure in GMC Formation II: The H_2 - Pressure Relation
• The Statistics of Supersonic Isothermal Turbulence
• Structural Analysis of Molecular Clouds: Dendrograms
• The Resolved Properties of Extragalactic Giant Molecular Clouds
• Filamentary structure of star-forming complexes
• Momentum Injection by Supernovae in the Interstellar Medium
• Physical properties of molecular clouds for the entire Milky Way disk
• Bulge Formation by the Coalescence of Giant Clumps in Primordial Disk Galaxies
• Bias-free Measurement of Giant Molecular Cloud Properties
• Star Formation in Disk Galaxies. I. Formation and Evolution of Giant Molecular Clouds via Gravitational Instability and Cloud Collisions
• ALMA Reveals the Molecular Medium Fueling the Nearest Nuclear Starburst
• Molecular Gas Properties on Cloud Scales Across the Local Star-forming Galaxy Population
• GMC formation by agglomeration and self gravity
• Cloud-cloud collisions and triggered star formation
• Comparing Numerical Methods for Isothermal Magnetized Supersonic Turbulence
• Molecular Gas in the Low Metallicity, Star Forming Dwarf IC 10
• The frequency and nature of `cloud-cloud collisions' in galaxies
• Rotation Curves in z~1-2 Star-Forming Disks: Evidence for Cored Dark Matter Distributions
• 'The Brick' is not a brick: A comprehensive study of the structure and dynamics of the Central Molecular Zone cloud G0.253+0.016
• Turbulence and star formation efficiency in molecular clouds: solenoidal versus compressive motions in Orion B
• Physical Properties of Molecular Clouds at 2 parsec Resolution in the Low-Metallicity Dwarf Galaxy NGC 6822 and the Milky Way
• Giant Molecular Clouds in the Early-Type Galaxy NGC4526
• Probing interstellar turbulence in cirrus with deep optical imaging: no sign of energy dissipation at 0.01 pc scale
• Revealing the intermediate-mass black hole at the heart of the dwarf galaxy NGC 404 with sub-parsec resolution ALMA observations
• Characterizing gravitational instability in turbulent multi-component galactic discs
• Evolutionary Description of Giant Molecular Cloud Mass Functions on Galactic Disks
• WISDOM Project -- IX Giant Molecular Clouds in the Lenticular Galaxy NGC4429: Effects of Shear and Tidal Forces on Clouds
• A Multi-wavelength Study of the Turbulent Central Engine of the Low-mass AGN hosted by NGC404
• Criteria for gravitational instability and quasi-isolated gravitational collapse in turbulent medium
• Obscuring fraction of active galactic nuclei implied by supernova and radiative feedbacks
• High Molecular Gas Masses in Absorption-selected Galaxies at $z\approx 2$
• The Interstellar Medium and Star Formation of Galactic Disks. I. ISM and GMC properties with Diffuse FUV and Cosmic Ray Backgrounds
• The turbulent gas structure in the centers of NGC253 and the Milky Way
• GMC Collisions as Triggers of Star Formation. VI. Collision-Induced Turbulence
• Mass-size scaling M~ r^1.67 of massive star-forming clumps -- evidences of turbulence-regulated gravitational collapse
• HI Clouds in LITTLE THINGS Dwarf Irregular Galaxies
• ALMA Resolves Giant Molecular Clouds in a Tidal Dwarf Galaxy
• Connection among environment, cloud-cloud collision speed, and star formation activity in the strongly barred galaxy NGC1300
• Physics of Non-Universal Larson's Relation

Cited by in corpus (4)

• WISDOM Project -- XV. Giant Molecular Clouds in the Central Region of the Barred Spiral Galaxy NGC 5806
• Molecular clouds in M51 from high-resolution extinction mapping
• Molecular cloud matching in CO and dust in M33 II. Physical properties of giant molecular clouds
• Spatially Resolved Star Formation relations in local LIRGs along the complete merger sequence