A general model for the identification of specific PAHs in the far-IR

Abstract

Context. In the framework of the interstellar PAH hypothesis, far-IR skeletal bands are expected to be a fingerprint of single species in this class. Aims. A detailed model of the photophysics of interstellar PAHs is required for such single-molecule identification of their far-IR features in the presently available Infrared Space Observatory data and in those of the forthcoming Herschel Space Observatory mission. Methods. We modelled the detailed photophysics of a vast sample of species in different radiation fields, using a compendium of Monte-Carlo techniques and quantum-chemical calculations. This enabled us to validate the use of purely theoretical data and assess the expected accuracy and reliability of the resulting synthetic far-IR emission spectra. Results. We produce positions and intensities of the expected far-IR features which ought to be emitted by each species in the sample in the considered radiation fields. A composite emission spectrum for our sample is computed for one of the most favourable sources for detection, namely the Red Rectangle nebula. The resulting spectrum is compared with the estimated dust emission in the same source, to assess the dependence of detectability on key molecular parameters. Conclusions. Identifying specific PAHs from their far-IR features is going to be a difficult feat in general, still it may well be possible under favourable conditions.

arXiv comment14 pages, 9 figures + 18 pages of online appendix. Accepted for publication in A&A (09/06/2006)

References in corpus (9)

• Interstellar Dust Grains
• Photoelectric Emission from Interstellar Dust: Grain Charging and Gas Heating
• Properties of the close binary and circumbinary torus of the Red Rectangle
• Diffuse Interstellar Bands in NGC 1448
• Discovery of Blue Luminescence in the Red Rectangle: Possible Fluorescence from Neutral Polycyclic Aromatic Hydrocarbon Molecules?
• Small PAHs in the Red Rectangle
• The Rotational Excitation Temperature of the $\lambda$6614 Diffuse Interstellar Band Carrier
• Diagnostics for specific PAHs in the far-IR: searching neutral naphthalene and anthracene in the Red Rectangle
• Estimated IR and phosphorescence emission fluxes for specific Polycyclic Aromatic Hydrocarbons in the Red Rectangle

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• Evidence for the naphthalene cation in a region of the interstellar medium with anomalous microwave emission
• Mixed aliphatic and aromatic composition of evaporating very small grains in NGC 7023 revealed by the 3.4/3.3 $\mu$m ratio
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• Theoretical evaluation of PAH dications properties
• Coupled Blind Signal Separation and Spectroscopic Database Fitting of the Mid Infrared PAH Features
• Search for corannulene (C20H10) in the Red Rectangle
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• Photo-processing of astro-PAHs
• Search for PAHs in the Perseus molecular cloud with the Green Bank Telescope
• Gas-phase spectroscopy of photostable PAH ions from the mid- to far-infrared
• Polycyclic Aromatic Hydrocarbon emission model in photodissociation regions I: Application to the 3.3, 6.2, and 11.2 $\mu$m bands