EDP Sciences Journals List
Advanced Search
Subscriber Authentication Point
Home All issues Volume 477/3 Article
Free access article

Issue A&A
Volume 477, Number 3, January III 2008
Page(s) 747 - 762
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20077203



A&A 477, 747-762 (2008)
DOI: 10.1051/0004-6361:20077203

Dense gas in luminous infrared galaxies

W. A. Baan1, C. Henkel2, A. F. Loenen3, 1, A. Baudry4, and T. Wiklind5

1  ASTRON, Oude Hoogeveensedijk 4, 7991 PD Dwingeloo, The Netherlands
    e-mail: baan@astron.nl
2  Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
3  Kapteyn Astronomical Institute, PO Box 800, 9700 AV Groningen, The Netherlands
4  Observatoire de l'Université de Bordeaux, 33270 Floirac, France
5  Onsala Space Observatory, 43900 Onsala, Sweden & Space Telescope Science Institute, Baltimore, Maryland 21218, USA

(Received 31 January 2007 / Accepted 16 October 2007 )

Abstract
Aims.Molecules that trace the high-density regions of the interstellar medium have been observed in (ultra-)luminous (far-)infrared galaxies, in order to initiate multiple-molecule multiple-transition studies to evaluate the physical and chemical environment of the nuclear medium and its response to the ongoing nuclear activity.
Methods.The HCN(1-0), HNC(1-0), ${\rm HCO}^+$(1-0), CN(1-0) and CN(2-1), CO(2-1), and CS(3-2) transitions were observed in sources covering three decades of infrared luminosity including sources with known OH megamaser activity. The data for the molecules that trace the high-density regions were augmented with data available in the literature.
Results.The integrated emissions of high-density tracer molecules show a strong relation to the far-infrared luminosity. Ratios of integrated line luminosities were used for a first-order diagnosis of the integrated molecular environment of the evolving nuclear starbursts. Diagnostic diagrams display significant differentiation among the sources that relate to the initial conditions and the radiative excitation environment. Initial differentiation was introduced between the FUV radiation field in photon-dominated-regions and the X-ray field in X-ray-dominated-regions. The galaxies displaying OH megamaser activity have line ratios typical of photon-dominated regions.


Key words: infrared: galaxies -- ISM: molecules -- radio line: galaxies -- galaxies: active -- galaxies: starburst -- masers



© ESO 2008


What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.
  • If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
  • You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
  • You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.