ALMA observations of CS in NGC 1068: chemistry and excitation
Artikel i vetenskaplig tidskrift, 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
Författare
M. Scourfield
University College London (UCL)
S. Viti
University College London (UCL)
S. Garcia-Burillo
Observatorio Astronómico Nacional (OAN)
A. Saintonge
University College London (UCL)
F. Combes
Centre national de la recherche scientifique (CNRS)
A. Fuente
Observatorio Astronómico Nacional (OAN)
C. Henkel
King Abdulaziz University
Max-Planck Institut für Radioastronomie
A. Alonso-Herrero
Centro de Astrobiología (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
Universiteit Leiden
Susanne Aalto
Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik
A. Usero
Observatorio Astronómico Nacional (OAN)
K. Kohno
University of Tokyo
Monthly Notices of the Royal Astronomical Society
0035-8711 (ISSN) 1365-2966 (eISSN)
Vol. 496 4 5308-5329Ämneskategorier
Astronomi, astrofysik och kosmologi
Atom- och molekylfysik och optik
Annan fysik
DOI
10.1093/mnras/staa1891