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Testing PDR models against ISO fine structure line data for extragalactic sources

Vasta, M; Barlow, MJ; Viti, S; Yates, JA; Bell, TA; (2010) Testing PDR models against ISO fine structure line data for extragalactic sources. Monthly Notices of the Royal Astronomical Society , 404 (4) pp. 1910-1921. 10.1111/j.1365-2966.2010.16402.x. Green open access

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Abstract

Far-infrared [C II] 158-μm, [O I] 145-μm and [O I] 63-μm fine structure emission-line fluxes were measured from archival Infrared Space Observatory Long Wavelength Spectrometer spectra of 46 extragalactic sources, with 28 sources providing detections in all three lines. For 12 of the sources, the contribution to the [C II] 158-μm line flux from H II regions could be estimated from their detected [N II] 122-μm line fluxes. The measured [C II]/[O I] and [O I] 63/145-μm line flux ratios were compared with those from a grid of photodissociation region (PDR) models previously computed using the UCL_PDR code. Persistent offsets between the observed and modelled line ratios could be partly attributed to the effects of [O I] 63-μm self-absorption. Using the Spherical Multi-Mol (SMMOL) code, we calculated model [O I] line profiles and found that the strength of the [O I] 63-μm line was reduced by 20–80 per cent, depending on the PDR parameters. We conclude that high PDR densities and radiation field strengths, coupled with the effects of [O I] 63-μm self-absorption, are likely to provide the best match to the observed line flux ratios.

Type: Article
Title: Testing PDR models against ISO fine structure line data for extragalactic sources
Open access status: An open access version is available from UCL Discovery
DOI: 10.1111/j.1365-2966.2010.16402.x
Publisher version: https://doi.org/10.1111/j.1365-2966.2010.16402.x
Language: English
Additional information: This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: astrochemistry, line: profiles, photodissociation region (PDR), Galaxy: fundamental parameters, infrared: galaxies
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Computer Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy
URI: https://discovery.ucl.ac.uk/id/eprint/10095510
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