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A study of heating and cooling of the ISM in NGC1097 with Herschel-PACS and Spitzer-IRS

  • P. Beirão
  • , L. Armus
  • , G. Helou
  • , P. N. Appleton
  • , J. D.T. Smith
  • , K. V. Croxall
  • , E. J. Murphy
  • , D. A. Dale
  • , B. T. Draine
  • , M. G. Wolfire
  • , K. M. Sandstrom
  • , G. Aniano
  • , A. D. Bolatto
  • , B. Groves
  • , B. R. Brandl
  • , E. Schinnerer
  • , A. F. Crocker
  • , J. L. Hinz
  • , H. W. Rix
  • , R. C. Kennicutt
  • D. Calzetti, A. Gil De Paz, G. Dumas, M. Galametz, K. D. Gordon, C. N. Hao, B. Johnson, J. Koda, O. Krause, T. Van Der Laan, A. K. Leroy, Y. Li, S. E. Meidt, J. D. Meyer, N. Rahman, H. Roussel, M. Sauvage, S. Srinivasan, L. Vigroux, F. Walter, B. E. Warren
  • California Institute of Technology
  • University of Toledo
  • Carnegie Institution of Washington
  • University of Wyoming
  • Princeton University
  • University of Maryland, College Park
  • Max Planck Institute for Astronomy
  • Leiden University
  • University of Massachusetts
  • University of Arizona
  • University of Cambridge
  • Complutense University
  • Space Telescope Science Institute
  • Tianjin Normal University
  • Institut d'Astrophysique de Paris
  • National Science Foundation
  • Stony Brook University
  • Université Paris VII
  • University of Western Australia

Research output: Contribution to journalArticlepeer-review

32 Scopus citations

Abstract

NGC1097 is a nearby Seyfert 1 galaxy with a bright circumnuclear starburst ring, a strong large-scale bar, and an active nucleus. We present a detailed study of the spatial variation of the far-infrared (FIR) [C II]158 μm and [O I]63 μm lines and mid-infrared H2 emission lines as tracers of gas cooling, and of the polycyclic aromatic hydrocarbon (PAH) bands as tracers of the photoelectric heating, using Herschel-PACS and Spitzer-IRS infrared spectral maps. We focus on the nucleus and the ring, and two star-forming regions (Enuc N and Enuc S). We estimated a photoelectric gas heating efficiency ([C II]158 μm+[O I]63 μm)/PAH in the ring about 50% lower than in Enuc N and S. The average 11.3/7.7 μm PAH ratio is also lower in the ring, which may suggest a larger fraction of ionized PAHs, but no clear correlation with [C II]158μm/PAH(5.5-14 μm) is found. PAHs in the ring are responsible for a factor of two more [C II]158 μm and [O I]63 μm emission per unit mass than PAHs in the Enuc S. spectral energy distribution (SED) modeling indicates that at most 25% of the FIR power in the ring and Enuc S can come from high-intensity photodissociation regions (PDRs), in which case G 0 102.3 and n H 103.5 cm-3 in the ring. For these values of G 0 and n H, PDR models cannot reproduce the observed H2 emission. Much of the H2 emission in the starburst ring could come from warm regions in the diffuse interstellar medium that are heated by turbulent dissipation or shocks.

Original languageEnglish
Article number144
JournalAstrophysical Journal
Volume751
Issue number2
DOIs
StatePublished - Jun 1 2012

Keywords

  • galaxies: ISM
  • galaxies: individual (NGC 1097)
  • galaxies: starburst
  • infrared: galaxies

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