Evolution of Molecular Clouds in the Superwind Galaxy NGC 1808 Probed by ALMA Observations

Abstract

ALMA imaging of the cold molecular medium in the nearby starburst galaxy NGC 1808 is presented. The observations reveal the distribution of molecular gas, traced by ${}^{12}$CO (1-0) and ${}^{12}$CO (3-2), and continuum (93 and 350 GHz) across the central 1 kpc starburst region at high resolution of $\sim 1$ arcsec. A molecular gas torus (radius $\sim 30$ pc) is discovered in the circumnuclear disk (CND; central 100 pc), with a high CO (3-2)/CO (1-0) ratio of $\sim 1$, surrounded by massive ($10^6$-$10^7$ $M_{\odot }$) clouds with high star formation efficiency (SFE$\sim 10^{-8}$ yr${}^{-1}$), molecular spiral arms, and a 500 pc pseudoring. The CND harbors a continuum core and molecular gas exhibiting peculiar motion. The new data confirm the line splitting along the minor galactic axis, interpreted as a nuclear gas outflow with average velocity $\sim 180$ km s${}^{-1}$, and show evidence of a velocity gradient of $\sim +0.4$ km s${}^{-1}$ pc${}^{-1}$ along the axis. In addition, supershells expanding from the 500 pc ring with maximum velocities of $\sim 75$ km s${}^{-1}$ are revealed. The distribution and CO luminosities of molecular clouds in the central 1 kpc starburst region indicate an evolutionary sequence, from gas accretion onto the 500 pc ring from the large-scale bar, to enhanced star formation in the ring, and outflow as feedback.

arXiv commentAccepted for publication in The Astrophysical Journal

References in corpus (63)

• The Global Schmidt Law in Star Forming Galaxies
• The CO-to-H2 Conversion Factor
• The Star Formation Efficiency in Nearby Galaxies: Measuring Where Gas Forms Stars Effectively
• The Star Formation Law in Nearby Galaxies on Sub-Kpc Scales
• Galactic Winds
• On the Maximum Luminosity of Galaxies and Their Central Black Holes: Feedback From Momentum-Driven Winds
• Massive Molecular Outflows and Evidence for AGN Feedback from CO Observations
• Calibrating Extinction-Free Star Formation Rate Diagnostics with 33GHz Free-Free Emission in NGC6946
• Mapping Large-Scale Gaseous Outflows in Ultraluminous Galaxies with Keck II ESI Spectra: Variations in Outflow Velocity with Galactic Mass
• Molecular line emission in NGC1068 imaged with ALMA. I An AGN-driven outflow in the dense molecular gas
• Clearing Out a Galaxy
• Secular Evolution Via Bar-Driven Gas Inflow: Results from BIMA SONG
• The Starburst-Driven Molecular Wind in NGC 253 and the Suppression of Star Formation
• The Evolution of ISM Mass Probed by Dust Emission -- ALMA Observations at z = 0.3 to 2
• Radiation pressure from massive star clusters as a launching mechanism for super-galactic winds
• 3D Integral Field Observations of Ten Galactic Winds - I. Extended phase (>10 Myr) of mass/energy injection before the wind blows
• Star formation in a galactic outflow
• An Origin for Multi-Phase Gas in Galactic Winds and Halos
• The Launching of Cold Clouds by Galaxy Outflows I: Hydrodynamic Interactions with Radiative Cooling
• ALMA resolves the torus of NGC 1068: continuum and molecular line emission
• Nuclear star formation activity and black hole accretion in nearby Seyfert galaxies
• Starburst-Driven Galactic Winds: Filament Formation and Emission Processes
• Star Formation in Massive Clusters via the Wilkinson Microwave Anisotropy Probe and the Spitzer Glimpse Survey
• The Carnegie-Irvine Galaxy Survey. I. Overview and Atlas of Optical Images
• ALMA reveals the feeding of the Seyfert 1 nucleus in NGC 1566
• The Spectral Energy Distribution of CO lines in M82
• How supernova explosions power galactic winds
• A Dynamical Model for the Formation of Gas Rings and Episodic Starbursts Near Galactic Centres
• Gas Inflow in Barred Galaxies - Effects of Secondary Bars
• Suppression of Star Formation in NGC 1266
• Dense Molecular Gas Tracers in the Outflow of the Starburst Galaxy NGC 253
• Quantifying Supernovae-Driven Multiphase Galactic Outflows
• ALMA Imaging of HCN, CS and dust in Arp 220 and NGC 6240
• A Dynamical Model for Gas Flows, Star Formation, and Nuclear Winds in Galactic Centres
• Multi-phase Nature of a Radiation-Driven Fountain with Nuclear Starburst in a Low-mass Active Galactic Nucleus
• AGN feedback: galactic-scale outflows driven by radiation pressure on dust
• SPIRE imaging of M82: cool dust in the wind and tidal streams
• Environmental regulation of cloud and star formation in galactic bars
• Stellar feedback as the origin of an extended molecular outflow in a starburst galaxy
• Formation of a Massive Black Hole at the Center of the Superbubble in M82
• Mid-Infrared Imaging of Active Galaxies: Active Nuclei and Embedded Star Clusters
• Extreme dust disks in Arp 220 as revealed by ALMA
• ALMA observations of 99 GHz free-free and H40$\alpha$ line emission from star formation in the centre of NGC 253
• Gas Dynamics and Outflow in the Barred Starburst Galaxy NGC 1808 Revealed with ALMA
• SMA CO(J=6-5) and 435 micron interferometric imaging of the nuclear region of Arp 220
• PAH emission variations within the resolved starbursts of NGC253 and NGC1808
• Bar-driven Fueling to a Galactic Central Reagin in a Massive Gas Disk
• Starburst--driven galactic outflows
• The Molecular Wind in the Nearest Seyfert Galaxy Circinus Revealed by ALMA
• Gas Dynamics in the LINER Galaxy NGC 5005: Episodic Fueling of a Nuclear Disk
• X-ray Emission from NGC 1808: More than a Complex Starburst
• Molecular Superbubbles and Outflows from Starburst Galaxy NGC 2146
• Starburst at the Expanding Molecular Superbubble in M82: Self-Induced Starburst at the Inner Edge of the Superbubble
• Star formation and gas flows in the centre of the NUGA galaxy NGC 1808 observed with SINFONI
• Dust-driven wind from disk galaxies
• Superbubble breakout and galactic winds from disk galaxies
• First Detection of A Sub-kpc Scale Molecular Outflow in the Starburst Galaxy NGC 3628
• Polycyclic Aromatic Hydrocarbon in the Central Region of the Seyfert 2 Galaxy NGC1808
• ALMA observations of the interaction of a radio jet with molecular gas in Minkowski's Object
• Extended HCN and HCO${}^{+}$ emission in the starburst galaxy M82
• The 200-pc Molecular Cylinder in the Galactic Centre
• Molecular outflows in starburst nuclei
• Constraint on the inflow/outflow rates in star-forming galaxies at z~1.4 from molecular gas observations

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• Shock-multicloud interactions in galactic outflows -- I. Cloud layers with log-normal density distributions
• Destruction and multiple ionization of PAHs by X-rays in circumnuclear regions of AGNs
• ALMA Observations of Atomic Carbon [C I] (${{}^3\mathrm{P}}_1\to {{}^3\mathrm{P}}_0$) and Low-$J$ CO Lines in the Starburst Galaxy NGC 1808
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• Three-Dimensional Structure of the Central Molecular Zone
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• The ALMaQUEST Survey XIV: do radial molecular gas flows affect the star-forming ability of barred galaxies?
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• CO Multi-line Imaging of Nearby Galaxies (COMING). VII. Fourier decomposition of molecular gas velocity fields and bar pattern speed
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