The physical characteristics of the gas in the disk of Centaurus a using the Herschel space observatory

Journal Article · Tue May 20 04:00:00 EDT 2014 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/787/1/16· OSTI ID:22356885

Parkin, T. J.; Wilson, C. D.; Schirm, M. R. P. ^[1]; Baes, M.; De Looze, I. ^[2]; Boquien, M.; Boselli, A. ^[3]; Cormier, D. ^[4]; Galametz, M. ^[5]; Karczewski, O. Ł. ^[6]; Lebouteiller, V.; Madden, S. C. ^[7]; Roussel, H. ^[8]; Smith, M. W. L. ^[9]

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1. Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, L8S 4M1 (Canada)
2. Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281 S9, B-9000 Gent (Belgium)
3. Laboratoire d'Astrophysique de Marseille, Université d'Aix-Marseille and CNRS, UMR7326, F-13388 Marseille Cedex 13 (France)
4. Institut für theoretische Astrophysik, Zentrum für Astronomie der Universität Heidelberg, Albert-Ueberle Str. 2, D-69120 Heidelberg (Germany)
5. Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge, CB3 0HA (United Kingdom)
6. Department of Physics and Astronomy, University of Sussex, Brighton, BN1 9QH (United Kingdom)
7. CEA, Laboratoire AIM, Université Paris VII, IRFU/Service d'Astrophysique, Bat. 709, Orme des Merisiers, F-91191 Gif-sur-Yvette (France)
8. Institut d'Astrophysique de Paris, UMR7095 CNRS, Université Pierre and Marie Curie, 98 bis Boulevard Arago, F-75014 Paris (France)
9. School of Physics and Astronomy, Cardiff University, The Parade, Cardiff CF24 3AA (United Kingdom)

We search for variations in the disk of Centaurus A of the emission from atomic fine structure lines using Herschel PACS and SPIRE spectroscopy. In particular, we observe the [C II](158 μm), [N II](122 and 205 μm), [O I](63 and 145 μm), and [O III](88 μm) lines, which all play an important role in cooling the gas in photo-ionized and photodissociation regions (PDRs). We determine that the ([C II]+[O I]{sub 63})/F {sub TIR} line ratio, a proxy for the heating efficiency of the gas, shows no significant radial trend across the observed region, in contrast to observations of other nearby galaxies. We determine that 10%-20% of the observed [C II] emission originates in ionized gas. Comparison between our observations and a PDR model shows that the strength of the far-ultraviolet radiation field, G {sub 0}, varies between 10{sup 1.75} and 10{sup 2.75} and the hydrogen nucleus density varies between 10{sup 2.75} and 10{sup 3.75} cm{sup –3}, with no significant radial trend in either property. In the context of the emission line properties of the grand-design spiral galaxy M51 and the elliptical galaxy NGC 4125, the gas in Cen A appears more characteristic of that in typical disk galaxies rather than elliptical galaxies.

• OSTI ID: 22356885
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 787; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
COMPARATIVE EVALUATIONS
DENSITY
DISSOCIATION
EMISSION
FAR ULTRAVIOLET RADIATION
GALAXIES
GALAXY NUCLEI
HYDROGEN
PERTURBED ANGULAR CORRELATION
PHOTOLYSIS
SPACE
SPECTROSCOPY