Full SED fitting with the KOSMA-τPDR code

Abstract

Aims. We revised the treatment of interstellar dust in the KOSMA-τ photo-dissociation region (PDR) model code to achieve a consistent description of the dust-related physics in the code. The detailed knowledge of the dust properties is then used to compute the dust continuum emission together with the line emission of chemical species. Methods. We coupled the KOSMA-τ PDR code with the multi component dust radiative transfer (MCDRT) code to to solve the frequency-dependent radiative transfer equations and the thermal balance equation in a dusty clump under the assumption of spherical symmetry, assuming thermal equilibrium in calculating the dust temperatures, neglecting non-equilibrium effects. We updated the calculation of the photoelectric heating and extended the parametrization range for the photoelectric heating toward high densities and UV fields. We revised the computation of the H 2 formation on grain surfaces to include the Eley-Rideal effect, thus allowing for high-temperature H 2 formation. Results. We demonstrate how the different optical properties, temperatures, and heating and cooling capabilities of the grains influence the physical and chemical structure of a model cloud. The most influential modification is the treatment of H 2 formation on grain surfaces that allows for chemisorption. This increases the total H 2 formation significantly and the connected H 2 formation heating provides a profound heating contribution in the outer layers of the model clumps. The contribution of polycyclic aromatic hydrocarbons (PAH) surfaces to the photoelectric heating and H 2 formation provides a boost to the temperature of outer cloud layers, which is clearly traced by high-J CO lines. Increasing the fraction of small grains in the dust size distribution results in hotter gas in the outer cloud layers caused by more efficient heating and cooler cloud centers, which is in turn caused by the more efficient FUV extinction.

[C II] 158μm and [N II] 205μm emission from IC 342

“…In an earlier paper (Röllig et al 2012) we presented early Stratospheric Observatory For Infrared Astronomy (SOFIA, Young et al 2012) observations of the [C II] 158 µm fine-structure transition of C + at 1900.536900 GHz and the 12 CO(11−10) transition at 1496.922909 GHz at two GMCs in the central molecular ring of IC 342. Using KOSMA-τ PDR model calculations (Störzer et al 1996;Röllig et al 2006Röllig et al , 2013 we were able to distinguish between a strong PDR/star-burst emission in the southern GMC E and the much more quiescent conditions in the cooler and denser GMC C in the northern arm, confirming the findings of Meier & Turner (2005).…”

The evolution of the star formation rate function in the EAGLE simulations: a comparison with UV, IR and Hα observations from z ∼ 8 to z ∼ 0

“…The dark green triangles of Fig. 1 represent the SFRFs of Duncan et al (2014), which were obtained following the SED fitting technique (Bruzual & Charlot 2003;Röllig et al 2013). In addition, we use the UV LFs from Bouwens et al (2015, z ∼ 4-10) and the dust corrections described in Section 2.…”

Temperatures of dust and gas in S 140

“…Dust and gas temperatures in a spherical PDR clump with a surface density of 10 5 cm −3 illuminated by an UV radiation field of 10 2 Draine fields. Gas temperatures generally exceed the dust temperatures (see Röllig et al 2013, for a more general discussion). The green dash-dotted line shows the visual extinction A V as a function of the depth into the cloud.…”