The Circumnuclear Molecular Gas in the Seyfert Galaxy NGC4945

Abstract

We have mapped the central region of NGC 4945 in the $J=2\to 1$ transition of ${}^{12}$CO, ${}^{13}$CO, and C${}^{18}$O, as well as the continuum at 1.3 mm, at an angular resolution of $5\farc \times 3\farc$ with the Submillimeter Array. The relative proximity of NGC 4945 (distance of only 3.8 Mpc) permits a detailed study of the circumnuclear molecular gas and dust in a galaxy exhibiting both an AGN (classified as a Seyfert 2) and a circumnuclear starburst in an inclined ring with radius $\sim$2\farcs5 ($\sim$50 pc). We find that all three molecular lines trace an inclined rotating disk with major axis aligned with that of the starburst ring and large-scale galactic disk, and which exhibits solid-body rotation within a radius of $\sim$5\farc ($\sim$95 pc). We infer an inclination for the nuclear disk of $62^{\circ }\pm 2^{\circ }$, somewhat smaller than the inclination of the large-scale galactic disk of $\sim$$78^{\circ }$. The continuum emission at 1.3 mm also extends beyond the starburst ring, and is dominated by thermal emission from dust. If it traces the same dust emitting in the far-infrared, then the bulk of this dust must be heated by star-formation activity rather than the AGN. We discover a kinematically-decoupled component at the center of the disk with a radius smaller than $1\farcs4$ (27 pc), but which spans approximately the same range of velocities as the surrounding disk. This component has a higher density than its surroundings, and is a promising candidate for the circumnuclear molecular torus invoked by AGN unification models.

arXiv comment13 pages, 10 figures,accepted by ApJ

References in corpus (13)

• The Submillimeter Array
• The Hubble flow around the CenA / M83 galaxy complex
• The effect of violent star formation on the state of the molecular gas in M82
• The Distribution of H2O Maser Emission in the Nucleus of NGC 4945
• A Survey for H${}_2$O Megamasers in Active Galactic Nuclei -- II. A Comparison of Detected and Undetected Galaxies
• Dense gas in nearby galaxies XVI. The nuclear starburst environment in NGC4945
• A Mapping Survey of the 12CO and 13CO Emission in Galaxies
• Molecular Superbubbles in the Starburst Galaxy NGC 253
• High-resolution X-ray imaging and spectroscopy of the core of NGC 4945 with XMM-Newton and Chandra
• Dynamically Influenced Molecular Clouds in the Nucleus of NGC 6946: Variations in the CO Isotopic Line Ratios
• Structure of the Circumnuclear Region of Seyfert 2 Galaxies Revealed by RXTE Hard X-ray Observations of NGC 4945
• Atomic and Molecular Gas in the Starburst Galaxy NGC4945
• Radio Recombination Lines from Starbursts: NGC 3256, NGC 4945 and the Circinus Galaxy

Cited by in corpus (34)

• SHINING, A Survey of Far Infrared Lines in Nearby Galaxies. I: Survey Description, Observational Trends, and Line Diagnostics
• Submillimeter-HCN Diagram for an Energy Diagnostics in the Centers of Galaxies
• Galactic nuclei evolution with spinning black holes: method and implementation
• Are there reliable methods to estimate the nuclear orientation of Seyfert galaxies?
• Blandford-Znajek jets in galaxy formation simulations: method and implementation
• SMA CO(J=6-5) and 435 micron interferometric imaging of the nuclear region of Arp 220
• The Dense Gas Fraction in Galactic Center Clouds
• Coronal-Line Forest AGN: the best view of the inner edge of the AGN torus?
• LABOCA observations of nearby, active galaxies
• The Sub-parsec Scale Radio Properties of Southern Starburst Galaxies. II. Supernova Remnants, the Supernova Rate, and the Ionised Medium in the NGC 4945 Starburst
• Super Star Clusters in the Central Starburst of NGC 4945
• HIFI Spectroscopy of ${\mathrm{H}}_2\mathrm{O}$ submm Lines in Nuclei of Actively Star Forming Galaxies
• ALMA view of the ${}^{12}$C/${}^{13}$C isotopic ratio in starburst galaxies
• Free-free and H42alpha emission from the dusty starburst within NGC 4945 as observed by ALMA
• Molecular line emission in NGC 4945, imaged with ALMA
• Detection of 36 GHz class I methanol maser emission towards NGCS253
• Extreme CO Isotopologue Line Ratios in ULIRGS: Evidence for a top-heavy IMF
• Hydrogen Fluoride toward Luminous Nearby Galaxies: NGC 253 and NGC 4945
• The deeply obscured AGN of NGC4945 I. Spitzer-IRS maps of [Ne V], [Ne II], H2 0-0 S(1), S(2), and other tracers
• The ionization rates of galactic nuclei and disks from Herschel/HIFI observations of water and its associated ions
• Gas-phase oxygen abundances and radial metallicity gradients in the two nearby spiral galaxies NGC7793 and NGC4945
• The forbidden high ionisation line region of the type 2 quasar Q1131+16: a clear view of the inner face of the torus?
• Detection of 36 GHz Class I Methanol Maser Emission Towards NGC 4945
• High-resolution mapping of the physical conditions in two nearby active galaxies based on 12CO(1-0), (2-1) and (3-2) lines
• Study of the PeV Neutrino, $\gamma$-rays and UHECRs around The Lobes of Centaurus A
• The Central Region of the Nearby Seyfert 2 Galaxy NGC 4945 : A Pair of Spirals
• Investigations of the Class I methanol masers in NGC 4945
• Physical conditions in nearby active galaxies correlated with ultra-high-energy cosmic rays detected by the Pierre Auger Observatory
• Variability in extragalactic class I methanol masers: New maser components toward NGC4945 and NGC253
• The multi-phase ISM in the nearby composite AGN-SB galaxy NGC 4945: large (parsecs) scale mechanical heating
• Positive feedback, quenching and sequential super star cluster (SSC) formation in NGC 4945
• 10 pc Scale Circumnuclear Molecular Gas Imaging of Nearby AGNs
• ArH+ and H2O+ absorption towards luminous galaxies
• Study of PeV neutrinos around dwarf galaxies near giant lobes of Centaurus A