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arXiv · 0807.1988

A clumpy-cloud PDR model of the global far-infrared line emission of the Milky Way

M. Cubick·J. Stutzki·V. Ossenkopf·C. Kramer·M. Röllig
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Abstract

The fractal structure of the interstellar medium suggests that the interaction of UV radiation with the ISM as described in the context of photon-dominated regions (PDR) dominates most of the physical and chemical conditions, and hence the far-infrared and submm emission from the ISM in the Milky Way. We investigate to what extent the Galactic FIR line emission of the important species CO, C, C+, and O, as observed by the Cosmic Background Explorer (COBE) satellite can be modeled in the framework of a clumpy, UV-penetrated cloud scenario. The far-infrared line emission of the Milky Way is modeled as the emission from an ensemble of clumps with a power law clump mass spectrum and mass-size relation with power-law indices consistent with the observed ISM structure. The individual clump line intensities are calculated using the KOSMA-tau PDR-model for spherical clumps. The model parameters for the cylindrically symmetric Galactic distribution of the mass density and volume filling factor are determined by the observed radial distributions. A constant FUV intensity, in which the clumps are embedded, is assumed. We show that this scenario can explain, without any further assumptions and within a factor of about 2, the absolute FIR-line intensities and their distribution with Galactic longitude as observed by COBE.

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M. Cubick, J. Stutzki, V. Ossenkopf, C. Kramer, M. Röllig. 2008-07-12. A clumpy-cloud PDR model of the global far-infrared line emission of the Milky Way. https://doi.org/10.1051/0004-6361:20079270

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