Physical Condition of Molecular Gas at the Centre of NGC 1097

Abstract

We have used the Xco conversion factor, Local Thermal Equilibrium and Large Velocity Gradient approximation to parametrize the cold and warm phase of the interstellar medium from five different low transitions of CO in the central 21"(kpc) of NGC 1097. We have applied a one-component model and derived a typical kinetic temperature of ~33K, and its molecular Hydrogen density and a CO column density. A two-component model results in 85% cold-to-total gas fraction with a 90K warm counterpart. Furthermore, we "resolve" the spatially unresolved single dish observations by selecting velocity channels that in an interferometric velocity map correspond to specific regions. We have selected five such regions and found that the physical properties in these regions are comparable to those derived from the full line profile. This implies that the central kpc of NGC 1097 is rather homogeneous in nature, and, although the regions are not uniquely located within the ring, the star formation along the ring is homogeneously distributed (in agreement with recent Herschel observations). We have further revised the mass inflow rate onto the Supermassive Black Hole in this prototype LINER/Sy1 galaxy and found that, accounting for the total interstellar medium and applying a careful contribution of the disc thickness and corresponding stability criterion, increases the previous estimations by a factor 10. Finally we have calculated the Xco for the centre of NGC 1097 using an independent estimation of the surface density to the CO emission, and obtained Xco=(2.8+-0.5)x10^20 cm^-2(K km s^-1)^-1 at radius 10.5" and Xco=(5.0+-0.5)x10^20 cm^-2(K km s^-1)^-1 at 7.5". With the approach and analysis described, we have demonstrated that important physical properties can be derived to a resolution beyond the single dish resolution element, however, caution is necessary for interpreting the results.(Abriged)

10 pages, 6 figures, 4 tables, Accepted for publication in MNRAS

References in corpus (9)

• A SINFONI view of Galaxy Centers: Morphology and Kinematics of five Nuclear Star Formation Rings
• Streaming Motions Towards the Supermassive Black Hole in NGC 1097
• Spectral Energy Distributions of Weak Active Galactic Nuclei Associated With Low-Ionization Nuclear Emission Regions
• CI and CO in nearby galaxy centers: the bright galaxies NGC1068 (M77), NGC2146, NGC3079, NGC4826 (M64), and NGC7469
• Mapping far-IR emission from the central kiloparsec of NGC 1097
• Interferometric 12CO(J=2-1) image of the Nuclear Region of Seyfert 1 Galaxy NGC 1097
• Far-Infrared Line Imaging of the Starburst Ring in NGC 1097 with the Herschel/PACS Spectrometer
• Spiral inflow feeding the nuclear starburst in M83, observed in H-alpha emission with the GHAFAS Fabry-Perot interferometer
• Imaging Carbon Monoxide Emission in the Starburst Galaxy NGC 6000

Cited by in corpus (6)

• 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
• Frequency and nature of central molecular outflows in nearby star-forming disk galaxies
• ALMA follows streaming of dense gas down to 40 pc from the supermassive black hole in NGC1097
• Bar pattern speed and position of the circumnuclear ring in NGC 1097
• On the disappearance of a cold molecular torus around the low-luminosity active galactic nucleus of NGC 1097