ALMA imaging of C2H emission in the disk of NGC1068

Abstract

We study the feedback of star formation and nuclear activity on the chemistry of molecular gas in NGC1068, a nearby (D=14Mpc) Seyfert 2 barred galaxy, by analyzing if the abundances of key molecular species like ethynyl (C2H), a classical tracer of PDR, change in the different environments of the disk of the galaxy. We have used ALMA to map the emission of the hyperfine multiplet of C2H(N=1-0) and its underlying continuum emission in the central r~35"(2.5kpc)-region of the disk of NGC1068 with a spatial resolution 1.0"x0.7"(50-70pc). We have developed a set of time-dependent chemical models to determine the origin of the C2H gas. A sizeable fraction of the total C2H line emission is detected from the r~1.3kpc starburst (SB) ring. However, the brightest C2H emission originates from a r~200pc off-centered circumnuclear disk (CND), where evidence of a molecular outflow has been previously found in other molecular tracers imaged by ALMA. We also detect significant emission that connects the CND with the outer disk. We derived the fractional abundances of C2H (X(C2H)) assuming LTE conditions. Our estimates range from X(C2H)~a few 10^-8 in the SB ring up to X(C2H)~ a few 10^-7 in the outflow region. PDR models that incorporate gas-grain chemistry are able to account for X(C2H) in the SB ring for moderately dense (n(H2)>10^4 cm^-3) and moderately UV-irradiated gas (UV-field<10xDraine field) in a steady-state regime. However, the high fractional abundances estimated for C2H in the outflow region can only be reached at very early times (T< 10^2-10^3 yr) in models of UV/X-ray irradiated dense gas (n(H2)>10^4-10^5) cm^-3). We interpret that the transient conditions required to fit the high values of X(C2H) in the outflow are likely due to UV/X-ray irradiated non-dissociative shocks associated with the highly turbulent interface between the outflow and the molecular gas in NGC1068.

A&A accepted, 14 pages, 7 figures, 6 Tables

References in corpus (25)

• Dust Masses, PAH Abundances, and Starlight Intensities in the SINGS Galaxy Sample
• 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
• A multi-transition HCN and HCO+ study of 12 nearby active galaxies: AGN versus SB environments
• A 2 mm spectral line survey of the starburst galaxy NGC 253
• The Herschel Comprehensive (U)LIRG Emission Survey (HerCULES): CO Ladders, fine structure lines, and neutral gas cooling
• Parametrization of C-shocks. Evolution of the Sputtering of Grains
• Molecular line emission in NGC1068 imaged with ALMA: II. The chemistry of the dense molecular gas
• UCLCHEM: A Gas-Grain Chemical Code
• The chemistry and spatial distribution of small hydrocarbons in UV-irradiated molecular clouds: the Orion Bar PDR
• High-Velocity Bipolar Molecular Emission from an AGN Torus
• Molecular line intensities as measures of cloud masses - I. Sensitivity of CO emissions to physical parameter variations
• Ethynyl (C2H) in massive star formation: Tracing the initial conditions?
• Multi-molecule ALMA observations towards the Seyfert 1 galaxy NGC 1097
• CI and CO in nearby galaxy centers: the bright galaxies NGC1068 (M77), NGC2146, NGC3079, NGC4826 (M64), and NGC7469
• On the maximum value of the cosmic abundance of oxygen and the oxygen yield
• Distributions of molecules in the circumnuclear disk and surrounding starburst ring in the Seyfert galaxy NGC 1068 observed with ALMA
• Molecular shock tracers in NGC 1068: SiO and HNCO
• A Multi-Transition Study of Molecules toward NGC 1068 based on High-Resolution Imaging Observations with ALMA
• A statistical study of giant molecular clouds traced by ${}^{13}$CO, C${}^{18}$O, CS, and CH${}_3$OH in the disk of NGC 1068 based on ALMA observations
• Modelling the ArH${}^{+}$ emission from the Crab Nebula
• Molecular transitions as probes of the physical conditions of extragalactic environments
• Large-Scale Spectroscopic Mapping of the $\rho$ Ophiuchi Molecular Cloud Complex I. The C${}_2$H to N${}_2$H${}^{+}$ Ratio as a Signpost of Cloud Characteristics
• Chemistry in isolation: High CCH/HCO+ line ratio in the AMIGA galaxy CIG 638
• First evidence for molecular interfaces between outflows and ambient cloud in high-mass star forming regions?

Cited by in corpus (24)

• Cool Outflows in Galaxies and their Implications
• An image of the dust sublimation region in the nucleus of NGC 1068
• Star formation and nuclear activity in luminous infrared galaxies: An infrared through radio review
• Separating Line Emission from Star Formation, Shocks, and AGN Ionisation in NGC 1068
• The Distribution and Origin of C${}_2$H in NGC 253 from ALCHEMI
• A molecular line survey toward the nearby galaxies NGC 1068, NGC 253, and IC 342 at 3 mm with the Nobeyama 45 m radio telescope: The data
• A 2-3 mm high-resolution molecular line survey towards the centre of the nearby spiral galaxy NGC 6946
• AGN torus detectability at sub-millimeter wavelengths: What to expect from ALMA continuum data
• The Kiloparsec-scale Neutral Atomic Carbon Outflow in the Nearby Type-2 Seyfert Galaxy NGC 1068: Evidence for Negative AGN Feedback
• Spatially resolved star-formation relations of dense molecular gas in NGC 1068
• A radio-jet driven outflow in the Seyfert 2 galaxy NGC 2110?
• AGN-driven Cold Gas Outflow of NGC 1068 Characterized by Dissociation-Sensitive Molecules
• The chemical footprint of AGN feedback in the outflowing circumnuclear disk of NGC 1068
• The IBISCO survey: I. Multiphase discs and winds in the Seyfert galaxy Markarian 509
• Vibrationally excited HC3N emission in NGC1068: Tracing the recent star formation in the starburst ring
• Photoionisation Modelling of the X-ray Emission Line Regions within the Seyfert 2 AGN NGC 1068
• Reconstructing the shock history in the CMZ of NGC 253 with ALCHEMI
• PDRs4All. XII. FUV-driven formation of hydrocarbon radicals and their relation with PAHs
• The Evolution of NGC 7465 as Revealed by its Molecular Gas Properties
• CON-quest II. Spatially and spectrally resolved HCN/HCO+ line ratios in local luminous and ultraluminous infrared galaxies
• Ultimate Merging at z~0.1
• ALMA uncovers optically thin and multi-component CO gas in the outflowing circumnuclear disk of NGC1068
• Implication of a galaxy-scale negative feedback by one of the most powerful multi-phase outflows in a hyper-luminous infrared galaxy at the intermediate redshift
• X-ray and CO-Derived Column Densities in AGN: A Study of Obscuration Properties in CTAGN and Non-CTAGN