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Title: SUBMILLIMETER LINE SPECTRUM OF THE SEYFERT GALAXY NGC 1068 FROM THE HERSCHEL-SPIRE FOURIER TRANSFORM SPECTROMETER

The first complete submillimeter spectrum (190-670 {mu}m) of the Seyfert 2 galaxy NGC 1068 has been observed with the SPIRE Fourier transform spectrometer on board the Herschel Space Observatory. The sequence of CO lines (J {sub up} = 4-13), lines from H{sub 2}O, the fundamental rotational transition of hydrogen fluoride, two o-H{sub 2}O{sup +} lines, and one line each from CH{sup +} and OH{sup +} have been detected, together with the two [C I] lines and the [N II] 205 {mu}m line. The observations in both single pointing mode with sparse image sampling and in mapping mode with full image sampling allow us to disentangle two molecular emission components, one due to the compact circumnuclear disk (CND) and one from the extended region encompassing the star-forming ring (SF-ring). Radiative transfer models show that the two CO components are characterized by densities of n(H{sub 2}) = 10{sup 4.5} and 10{sup 2.9} cm{sup -3} and temperatures of T {sub kin} = 100 K and 127 K, respectively. A comparison of the CO line intensities with the photodissociation region (PDR) and X-ray-dominated region (XDR) models, together with the other observational constraints, such as the observed CO surface brightness and the radiation field, indicatesmore » that the best explanation for the CO excitation of the CND is an XDR with a density of n(H{sub 2}) {approx} 10{sup 4} cm{sup -3} and an X-ray flux of 9 erg s{sup -1} cm{sup -2}, consistent with illumination by the active galactic nucleus, while the CO lines in the SF-ring are better modeled by a PDR. The detected water transitions, together with those observed with the Herschel PACS spectrometer, can be modeled by a large velocity gradient model with low temperature (T {sub kin} {approx} 40 K) and high density (n(H{sub 2}) in the range 10{sup 6.7}-10{sup 7.9} cm{sup -3}). The emission of H{sub 2}O{sup +} and OH{sup +} are in agreement with PDR models with cosmic-ray ionization. The diffuse ionized atomic component observed through the [N II] 205 {mu}m line is consistent with previous photoionization models of the starburst.« less
Authors:
; ;  [1] ; ; ;  [2] ; ; ; ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [8] ;  [9]
  1. Istituto di Astrofisica e Planetologia Spaziali, INAF-IAPS, Via Fosso del Cavaliere 100, I-00133 Roma (Italy)
  2. Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, L8S 4M1 (Canada)
  3. Center for Astrophysics and Space Astronomy, 389-UCB, University of Colorado, Boulder, CO 80303 (United States)
  4. UK ALMA Regional Centre Node, Jordell Bank Center for Astrophysics, School of Physics and Astronomy, University of Manchester, Oxford Road, Manchester M13 9PL (United Kingdom)
  5. CEA, Laboratoire AIM, Irfu/SAp, Orme des Merisiers, F-91191 Gif-sur-Yvette (France)
  6. Astronomy Department, University of Maryland, College Park, MD 20742 (United States)
  7. Laboratoire d'Astrophysique de Marseille-LAM, Universite d'Aix-Marseille and CNRS, UMR7326, 38 rue F. Joliot-Curie, F-13388 Marseille Cedex 13 (France)
  8. Center for Cosmology, Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States)
  9. Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey RH5 6NT (United Kingdom)
Publication Date:
OSTI Identifier:
22086519
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 758; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTROPHYSICS; CARBON MONOXIDE; COSMIC RADIATION; EMISSION SPECTRA; EMISSION SPECTROSCOPY; EXCITATION; FOURIER TRANSFORM SPECTROMETERS; GALAXY NUCLEI; HYDROGEN; HYDROGEN FLUORIDES; HYDROXIDES; ION EMISSION; PHOTOIONIZATION; RADIANT HEAT TRANSFER; RADIOASTRONOMY; SEYFERT GALAXIES; STARS; X RADIATION