A photon dominated region code comparison study
Creators
- Röllig, M.1, 2
- Abel, N. P.3
- Bell, T.4, 5
- Bensch, F.1
- Black, J.6
- Ferland, G. J.3
- Jonkheid, B.7
- Kamp, I.8
- Kaufman, M. J.
- Le Bourlot, J.9
- Le Petit, F.9, 6
- Meijerink, R.7
- Morata, O.
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Ossenkopf, V.2
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Roueff, E.9
- Shaw, G.3
- Spaans, M.10
- Sternberg, A.11
- Stutzki, J.2
- Thi, W.-F.12
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van Dishoeck, E. F.7
- van Hoof, P. A. M.13
- Viti, S.4
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Wolfire, M. G.14
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1.
University of Bonn
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2.
University of Cologne
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3.
University of Kentucky
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4.
University College London
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5.
California Institute of Technology
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6.
Chalmers University of Technology
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7.
Leiden University
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8.
Space Telescope Science Institute
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9.
Laboratory Universe and Theories
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10.
University of Groningen
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11.
Tel Aviv University
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12.
Royal Observatory
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13.
Royal Observatory of Belgium
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14.
University of Maryland, College Park
Abstract
Aims. We present a comparison between independent computer codes, modeling the physics and chemistry of interstellar photon dominated regions (PDRs). Our goal was to understand the mutual differences in the PDR codes and their effects on the physical and chemical structure of the model clouds, and to converge the output of different codes to a common solution. Methods. A number of benchmark models have been created, covering low and high gas densities n = 10^3, 10^(5.5) cm^(-3) and far ultraviolet intensities χ = 10, 10^5 in units of the Draine field (FUV: 6 < h υ < 13.6 eV). The benchmark models were computed in two ways: one set assuming constant temperatures, thus testing the consistency of the chemical network and photo-processes, and a second set determining the temperature self consistently by solving the thermal balance, thus testing the modeling of the heating and cooling mechanisms accounting for the detailed energy balance throughout the clouds. Results. We investigated the impact of PDR geometry and agreed on the comparison of results from spherical and plane-parallel PDR models. We identified a number of key processes governing the chemical network which have been treated differently in the various codes such as the effect of PAHs on the electron density or the temperature dependence of the dissociation of CO by cosmic ray induced secondary photons, and defined a proper common treatment. We established a comprehensive set of reference models for ongoing and future PDR model bench-marking and were able to increase the agreement in model predictions for all benchmark models significantly. Nevertheless, the remaining spread in the computed observables such as the atomic fine-structure line intensities serves as a warning that there is still a considerable uncertainty when interpreting astronomical data with our models.
Additional Information
© ESO 2007. Received 27 June 2006. Accepted 2 February 2007 We thank the Lorentz Center, Leiden, for hosting the workshop and for the perfect organization, supplying a very productive environment. The workshop and this work was partly funded by the Deutsche Forschungs Gesellschaft DFG via Grant SFB494 and by a Spinoza grant from the Netherlands Organization for Scientific Research (NWO). We also would like to thank the referee and the editor for making helpful suggestions which helped to improve the manuscript.Attached Files
Published - ROLaanda07.pdf
Files
ROLaanda07.pdf
Additional details
Identifiers
- Eprint ID
- 16735
- Resolver ID
- CaltechAUTHORS:20091117-135414524
Funding
- Deutsche Forschungs Gesellschaft (DFG)
- SFB494
- Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)
Dates
- Created
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2009-11-25Created from EPrint's datestamp field
- Updated
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2021-11-08Created from EPrint's last_modified field