Dense molecular gas in the starburst nucleus of NGC 1808

Abstract

Dense molecular gas tracers in the central 1 kpc region of the superwind galaxy NGC 1808 have been imaged by ALMA at a resolution of 1" (~50 pc). Integrated intensities and line intensity ratios of HCN (1-0), H${}^{13}$CN (1-0), HCO${}^{+}$ (1-0), H${}^{13}$CO${}^{+}$ (1-0), HOC${}^{+}$ (1-0), HCO${}^{+}$ (4-3), CS (2-1), C${}_2$H (1-0), and previously detected CO (1-0) and CO (3-2) are presented. SiO (2-1) and HNCO (4-3) are detected toward the circumnuclear disk (CND), indicating the presence of shocked dense gas. There is evidence that an enhanced intensity ratio of HCN(1-0)/HCO${}^{+}$(1-0) reflects star formation activity, possibly in terms of shock heating and electron excitation in the CND and a star-forming ring at radius ~300 pc. A non-LTE analysis indicates that the molecular gas traced by HCN, H${}^{13}$CN, HCO${}^{+}$, and H${}^{13}$CO${}^{+}$ in the CND is dense ($n_{{\mathrm{H}}_2}$~$10^5$ cm${}^{-3}$) and warm (20 K$<T_{\mathrm{k}}$<100 K). The calculations yield a low average gas density of $n_{{\mathrm{H}}_2}$~$10^2-10^3$ cm${}^{-3}$ for a temperature of $T_{\mathrm{k}}\ge 30$ K in the nuclear outflow. Dense gas tracers HCN (1-0), HCO${}^{+}$ (1-0), CS (2-1), and C${}_2$H (1-0) are detected for the first time in the superwind of NGC 1808, confirming the presence of a velocity gradient in the outflow direction.

arXiv commentAccepted for publication in ApJ

References in corpus (61)

• A computer program for fast non-LTE analysis of interstellar line spectra
• An atomic and molecular database for analysis of submillimetre line observations
• Galactic Winds
• On the Maximum Luminosity of Galaxies and Their Central Black Holes: Feedback From Momentum-Driven Winds
• The Critical Density and the Effective Excitation Density of Commonly Observed Molecular Dense Gas Tracers
• Molecular line emission in NGC1068 imaged with ALMA. I An AGN-driven outflow in the dense molecular gas
• How to Calculate Molecular Column Density
• The Starburst-Driven Molecular Wind in NGC 253 and the Suppression of Star Formation
• Are PAHs precursors of small hydrocarbons in Photo--Dissociation Regions? The Horsehead case
• A multi-transition HCN and HCO+ study of 12 nearby active galaxies: AGN versus SB environments
• Chemistry in Infrared Dark Cloud Clumps: a Molecular Line Survey at 3 mm
• The anatomy of the Orion B Giant Molecular Cloud: A local template for studies of nearby galaxies
• X-ray Properties of LINERs and Low-luminosity Seyfert Galaxies Observed with ASCA. I. Observations and Results
• Molecular Gas Chemistry in AGN I. The IRAM Survey of NGC1068
• Molecular line emission in NGC1068 imaged with ALMA: II. The chemistry of the dense molecular gas
• Dense gas in luminous infrared galaxies
• A molecular survey of outflow gas: velocity-dependent shock chemistry and the peculiar composition of the EHV gas
• Molecules as tracers of galaxy evolution: an EMIR survey. I. Presentation of the data and first results
• Molecular Line Emission as a Tool for Galaxy Observations (LEGO). I. HCN as a tracer of moderate gas densities in molecular clouds and galaxies
• High resolution observations of HCN and HCO+ J=3-2 in the disk and outflow of Mrk231 -Detection of vibrationally excited HCN in the warped nucleus
• ALMA Multi-line Imaging of the Nearby Starburst Galaxy NGC 253
• Quantifying Supernovae-Driven Multiphase Galactic Outflows
• Dense Molecular Gas Tracers in the Outflow of the Starburst Galaxy NGC 253
• HCN versus HCO+ as dense molecular gas mass tracer in Luminous Infrared Galaxies
• Irradiated ISM: Discriminating between Cosmic Rays and X-rays
• Lambda = 3 mm line survey of nearby active galaxies
• Submillimeter ALMA Observations of the Dense Gas in the Low-Luminosity Type-1 Active Nucleus of NGC 1097
• Multi-molecule ALMA observations towards the Seyfert 1 galaxy NGC 1097
• Tracing the envelopes around embedded low-mass young stellar objects with HCO+ and millimeter-continuum observations
• Submillimeter-HCN Diagram for an Energy Diagnostics in the Centers of Galaxies
• Enhanced HCN(1-0) Emission in the Type-1 Seyfert Galaxy NGC 1097
• Electron Excitation of High Dipole Moment Molecules Reexamined
• Winds of change - a molecular outflow in NGC 1377? The anatomy of an extreme FIR-excess galaxy
• Spatially Resolved Chemistry in Nearby Galaxies II. The Nuclear Bar in Maffei 2
• Millimeter Interferometric Investigations of the Energy Sources of Three Ultraluminous Infrared Galaxies, UGC 5101, Mrk 273, and IRAS 17208-0014, based on HCN to HCO+ Ratios
• Modeling The Molecular Composition in an AGN Disk
• Gas Dynamics and Outflow in the Barred Starburst Galaxy NGC 1808 Revealed with ALMA
• Distributions of molecules in the circumnuclear disk and surrounding starburst ring in the Seyfert galaxy NGC 1068 observed with ALMA
• On the chemistry and distribution of HOC+ in M82: More evidence for extensive PDRs
• C${}_2$H observations toward the Orion Bar
• Resolving the Bright HCN(1-0) Emission toward the Seyfert 2 Nucleus of M51: Shock Enhancement by Radio Jets and Weak Masing by Infrared Pumping?
• ALMA Observations of Nearby Luminous Infrared Galaxies with Various AGN Energetic Contributions Using Dense Gas Tracers
• Survey of Water and Ammonia in Nearby galaxies (SWAN): Resolved Ammonia Thermometry, Water and Methanol Masers in the Nuclear Starburst of NGC 253
• Spectral Line Survey toward Molecular Clouds in the Large Magellanic Cloud
• Molecular shock tracers in NGC 1068: SiO and HNCO
• Molecular-Cloud-Scale Chemical Composition I: Mapping Spectral Line Survey toward W51 in the 3 mm Band
• X-ray Emission from NGC 1808: More than a Complex Starburst
• A Multi-Transition Study of Molecules toward NGC 1068 based on High-Resolution Imaging Observations with ALMA
• Spectral Line Survey toward a Molecular Cloud in IC10
• Diverse nuclear star-forming activities in the heart of NGC 253 resolved with ten-pc scale ALMA images
• Star formation and gas flows in the centre of the NUGA galaxy NGC 1808 observed with SINFONI
• Probing Circumnuclear Environments with the HCN(J = 3-2) and HCO+(J = 3-2) lines: Case of NGC 1097
• Extended HCN and HCO${}^{+}$ emission in the starburst galaxy M82
• Spatially Resolved Chemistry in Nearby Galaxies III. Dense Molecular Gas in the Inner Disk of the LIRG IRAS 04296+2923
• ALMA multiline observations toward the central region of NGC 613
• Evolution of Molecular Clouds in the Superwind Galaxy NGC 1808 Probed by ALMA Observations
• The Molecular Baryon Cycle of M82
• Molecular Distribution in the Spiral Arm of M51
• Hot Ammonia in the Center of the Seyfert 2 galaxy NGC 3079
• Chemistry in isolation: High CCH/HCO+ line ratio in the AMIGA galaxy CIG 638
• Dense circum-nuclear molecular gas in starburst galaxies

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• Incorporating Astrochemistry into Molecular Line Modelling via Emulation
• Spatially-resolved Dense Molecular Gas Excitation in the Nearby LIRG VV 114
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• Excitation and acceleration of molecular outflows in LIRGs: The extended ESO 320-G030 outflow on 200-pc scales
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