ALMA observations of CS in NGC 1068: chemistry and excitation
Journal article, 2020

We present results from Atacama Large Millimeter/submillimeter Array (ALMA) observations of CS from the nearby galaxy NGC 1068 (similar to 14 Mpc). This Seyfert 2 barred galaxy possesses a circumnuclear disc (CND, r similar to 200 pc) and a starburst ring (SB ring, r similar to 1.3 kpc). These high-resolution maps (similar to 0.5 arcsec, similar to 35 pc) allow us to analyse specific sub-regions in the galaxy and investigate differences in line intensity ratios and physical conditions, particularly those between the CND and SB ring. Local thermodynamic equilibrium (LTE) analysis of the gas is used to calculate CS densities in each sub-region, followed by the non-LTE analysis conducted using the radiative transfer code RADEX to fit observations and constrain gas temperature, CS column density and hydrogen density. Finally, the chemical code UCLCHEM is used to reconstruct the gas, allowing an insight into its origin and chemical history. The density of hydrogen in the CND is found to be >= 10(5) cm(-2), although exact values vary, reaching 10(6) cm(-2) at the active galactic nucleus. The conditions in the two arms of the SB ring appear similar to one another, though the density found (similar to 10(4) cm(-2)) is lower than in the CND. The temperature in the CND increases from east to west, and is also overall greater than found in the SB ring. These modelling methods indicate the requirement for multiphase gas components in order to fit the observed emission over the galaxy. A larger number of high-resolution transitions across the SLED may allow for further constraining of the conditions, particularly in the SB ring.

galaxies: individual: NGC 1068

galaxies: ISM

galaxies: nuclei

radio lines: galaxies


M. Scourfield

University College London (UCL)

S. Viti

University College London (UCL)

S. Garcia-Burillo

Spanish National Observatory (OAN)

A. Saintonge

University College London (UCL)

F. Combes

Centre national de la recherche scientifique (CNRS)

A. Fuente

Spanish National Observatory (OAN)

C. Henkel

King Abdulaziz University

Max-Planck Institute for Radio Astronomy

A. Alonso-Herrero

Spanish Astrobiology Center (INTA-CSIC)

N. Harada

Academia Sinica

S. Takano

Nihon University

T. Nakajima

Nagoya University

S. Martin

Atacama Large Millimeter-submillimeter Array (ALMA)

European Southern Observatory Santiago

M. Krips

Institut de Radioastronomie Millimétrique (IRAM)

P. P. van der Werf

Leiden University

Susanne Aalto

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics

A. Usero

Spanish National Observatory (OAN)

K. Kohno

University of Tokyo

Monthly Notices of the Royal Astronomical Society

0035-8711 (ISSN) 1365-2966 (eISSN)

Vol. 496 4 5308-5329

Subject Categories

Astronomy, Astrophysics and Cosmology

Atom and Molecular Physics and Optics

Other Physics Topics



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