Full SED fitting with the KOSMA-τ PDR code - I. Dust modelling

Abstract

We revised the treatment of interstellar dust in the KOSMA-τ 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. We coupled the KOSMA-τ PDR code with the MCDRT (multi component dust radiative transfer) code 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 H2 formation on grain surfaces to include the Eley-Rideal effect, thus allowing for high-temperature H2 formation. 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 H2 formation on grain surfaces that allows for chemisorption. This increases the total H2 formation significantly and the connected H2 formation heating provides a profound heating contribution in the outer layers of the model clumps. The contribution of PAH surfaces to the photoelectric heating and H2 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.

accepted for publication in A&A

References in corpus (13)

• Complex Chemistry in Star-Forming Regions: An Expanded Gas-Grain Warm-up Chemical Model
• Photoprocesses in protoplanetary disks
• [CII] 158$\mu$m Emission and Metallicity in PDRs
• Surface chemistry in the interstellar medium - I - H2 formation by Langmuir-Hinshelwood and Eley-Rideal mechanisms
• Multilayer modeling of porous grain surface chemistry I. The GRAINOBLE model
• Desorption From Interstellar Ices
• Chemical Rates on Small Grains and PAHs: C^+ Recombination and H_2 Formation
• The penetration of FUV radiation into molecular clouds
• Excitation of H${}_2$ in photodissociation regions as seen by Spitzer
• Photodissociation of small carbonaceous molecules of astrophysical interest
• Strong CH+ J=1-0 emission and absorption in DR21
• Sensitivity of PDR Calculations to Microphysical Details
• Herschel observations of extra-ordinary sources: Detecting spiral arm clouds by CH absorption lines

Cited by in corpus (32)

• Photodissociation and photoionisation of atoms and molecules of astrophysical interest
• Photodissociation and X-Ray Dominated Regions
• Structure of photodissociation fronts in star-forming regions revealed by observations of high-J CO emission lines with Herschel
• PDRs4All: A JWST Early Release Science Program on radiative feedback from massive stars
• Carbon Fractionation in PDRs
• The evolution of the star formation rate function in the EAGLE simulations: A comparison with UV, IR and H$\alpha$ observations from z ~ 8 to z ~ 0
• Modelling clumpy PDRs in 3D - Understanding the Orion Bar stratification
• [CII] 158 μm self-absorption and optical depth effects
• The CO-dark molecular gas mass in 30 Doradus
• The picture of BLR in 2.5-D FRADO: Dynamics & Geometry
• The PhotoDissociation Region Toolbox: Software and Models for Astrophysical Analysis
• Velocity profiles of [CII], [CI], CO, and [OI] and physical conditions in four star-forming regions in the Large Magellanic Cloud
• Radiation pressure on dust explains the Low Ionized Broad Emission Lines in Active Galactic Nuclei
• PDFchem: A new fast method to determine ISM properties and infer environmental parameters using probability distributions
• Mid-J CO observations of Perseus B1-East 5: evidence for turbulent dissipation via low-velocity shocks
• The KOSMA-$\tau$ PDR Model -- I. Recent updates to the numerical model of photo-dissociated regions
• Dust-driven wind as a model of Broad Absorption Line quasars
• [CII] 158$\mu$m and [NII] 205$\mu$m emission from IC 342 - Disentangling the emission from ionized and photo-dissociated regions
• Temperatures of dust and gas in S~140
• Globules and pillars in Cygnus X III. Herschel and upGREAT/SOFIA far-infrared spectroscopy of the globule IRAS 20319+3958 inCygnus X
• The warm CO gas along the UV-heated outflow cavity walls: a possible interpretation for the Herschel/PACS CO spectra of embedded YSOs
• BLR size in Realistic FRADO Model: The role of shielding effect
• The link between gas and stars in the S254-S258 star-forming region
• A PDR model for the FIR mid-$J$ CO ladder with universal rotational temperature in star forming region
• Detection of the [O I] 63 $\mu$m emission line from the $z=6.04$ quasar J2054-0005
• Ionized Carbon in Galaxies: The [C II] 158 $\mu$m Line as a Total Molecular Gas Mass Tracer Revisited
• Warm ISM in the Sgr A Complex. II. The [C/N] abundance ratio traced by [CII] 158 um and [NII] 205 um observations toward the Arched Filaments at the Galactic center
• The Wind Dynamics of Super-Eddington Sources in FRADO
• Effects of grain temperature distribution on organic protostellar envelope chemistry
• First Submillimeter Lights from Dome A: Tracing the Carbon Cycle in the Feedback of Massive Stars
• Non-thermal emission from fall-back clouds in the Broad-Line Region of Active Galactic Nuclei
• Stellar feedback and triggered star formation in the prototypical bubble RCW 120