WISDOM Project -- XV. Giant Molecular Clouds in the Central Region of the Barred Spiral Galaxy NGC 5806

Abstract

We present high spatial resolution ($\approx 24$ pc) Atacama Large Millimeter/sub-millimeter Array ${}^{12}$CO(2-1) observations of the central region of the nearby barred spiral galaxy NGC 5806. NGC 5806 has a highly structured molecular gas distribution with a clear nucleus, a nuclear ring and offset dust lanes. We identify $170$ spatially- and spectrally-resolved giant molecular clouds (GMCs). These clouds have comparable sizes ($R_{\mathrm{c}}$) and larger gas masses, observed linewidths (${\sigma }_{\mathrm{obs},\mathrm{los}}$) and gas mass surface densities than those of clouds in the Milky Way disc. The size -- linewidth relation of the clouds is one of the steepest reported so far (${\sigma }_{\mathrm{obs},\mathrm{los}}\propto R_{\mathrm{c}}^{1.20}$), the clouds are on average only marginally bound (with a mean virial parameter $⟨{\alpha }_{\mathrm{vir}}⟩\approx 2$), and high velocity dispersions are observed in the nuclear ring. These behaviours are likely due to bar-driven gas shocks and inflows along the offset dust lanes, and we infer an inflow velocity of $\approx 120$ kms${}^{-1}$ and a total molecular gas mass inflow rate of $\approx 5$ M${}_{\odot }$ yr${}^{-1}$ into the nuclear ring. The observed internal velocity gradients of the clouds are consistent with internal turbulence. The number of clouds in the nuclear ring decreases with azimuthal angle downstream from the dust lanes without clear variation of cloud properties. This is likely due to the estimated short lifetime of the clouds ($\approx 6$ Myr), which appears to be mainly regulated by cloud-cloud collision and/or shear processes. Overall, it thus seems that the presence of the large-scale bar and gas inflows to the centre of NGC 5806 affect cloud properties.

Accepted for publication in MNRAS, 20 pages, 16 figures

References in corpus (35)

• Some Aspects of Measurement Error in Linear Regression of Astronomical Data
• The Resolved Properties of Extragalactic Giant Molecular Clouds
• Physical properties of molecular clouds for the entire Milky Way disk
• Bias-free Measurement of Giant Molecular Cloud Properties
• The lifecycle of molecular clouds in nearby star-forming disc galaxies
• Fast and inefficient star formation due to short-lived molecular clouds and rapid feedback
• The dynamical evolution of molecular clouds near the Galactic Centre - I. Orbital structure and evolutionary timeline
• ALMA Reveals the Molecular Medium Fueling the Nearest Nuclear Starburst
• The link between turbulence, magnetic fields, filaments, and star formation in the Central Molecular Zone cloud G0.253+0.016
• Dynamically Driven Evolution of the Interstellar Medium in M51
• Giant Molecular Cloud Catalogues for PHANGS-ALMA: Methods and Initial Results
• Molecular Gas Properties on Cloud Scales Across the Local Star-forming Galaxy Population
• Gas flow in barred potentials
• The MUSE Atlas of Disks (MAD): Resolving Star Formation Rates and Gas Metallicities on < 100pc Scales
• Giant Molecular Clouds in M31: I - Molecular Cloud Properties
• The Central Kiloparsec of Seyfert and Inactive Host Galaxies: a Comparison of Two-Dimensional Stellar and Gaseous Kinematics
• Short GMC lifetimes: an observational estimate with the PdBI Arcsecond Whirlpool Survey (PAWS)
• Environmental dependence of the molecular cloud lifecycle in 54 main sequence galaxies
• Giant Molecular Clouds in the Early-Type Galaxy NGC4526
• 2D Bayesian automated tilted-ring fitting of disk galaxies in large HI galaxy surveys: 2DBAT
• WISDOM Project -- X. The morphology of the molecular ISM in galaxy centres and its dependence on galaxy structure
• WISDOM Project -- IX Giant Molecular Clouds in the Lenticular Galaxy NGC4429: Effects of Shear and Tidal Forces on Clouds
• ALMA observation of the disruption of molecular gas in M87
• Rotation of molecular clouds in M~51
• Boxy/Peanut/X-shape bulges: steep inner rotation curve leads to barlens face-on morphology
• Properties of giant molecular clouds in the strongly barred galaxy NGC1300
• The Interstellar Medium and Star Formation of Galactic Disks. I. ISM and GMC properties with Diffuse FUV and Cosmic Ray Backgrounds
• GMC Collisions as Triggers of Star Formation. VI. Collision-Induced Turbulence
• Molecular gas kinematics in the nuclear region of nearby Seyfert galaxies with ALMA
• WISDOM Project XII. Clump properties and turbulence regulated by clump-clump collisions in the dwarf galaxy NGC404
• ALMA uncovers highly filamentary structure towards the Sgr E region
• WISDOM project -- XI. Star Formation Efficiency in the Bulge of the AGN-host Galaxy NGC 3169 with SITELLE and ALMA
• Towards a multi-tracer timeline of star formation in the LMC -- II. The formation and destruction of molecular clouds
• Physics of Non-Universal Larson's Relation
• 3D Studies of Neutral and Ionised Gas and Stars in Seyfert and Inactive Galaxies

Cited by in corpus (7)

• Reconciling extragalactic star formation efficiencies with theory: insights from PHANGS
• Molecular clouds in M51 from high-resolution extinction mapping
• Mapping the Active Galactic Nucleus Effects on the Stellar and Gas Properties of NGC 5806
• WISDOM project -- XVIII. Molecular gas distributions and kinematics of three megamaser galaxies
• Simulating nearby disc galaxies on the main star formation sequence II. The gas structure transition in low and high stellar mass discs
• 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