C. C. Popescu, R. J. Tuffs
The observational signatures of many of the most fundamental physical attributes of galaxies, including the mass of the interstellar gas in both atomic and molecular form, the thermodynamical properties of this gas, as well as the ambient magnetic fields and cosmic rays depend on the strength and colours of the ambient radiation fields, which however are generally not directly observable in star-forming galaxies. Here we provide and describe a library of diffuse stellar radiation fields in spiral galaxies derived using calculations of the transfer of stellar radiation from the main morphological components - disks, thin disks, and bulges - through the dusty interstellar medium. These radiation fields are self-consistent with the solutions for the integrated panchromatic spectral energy distributions (SEDs) previously presented using the same model. Because of this, observables calculated from the radiation fields, such as gamma-ray or radio emission, can be self-consistently combined with the solutions for the UV/optical/submm SEDs, thus expanding the range of applicability of the radiation transfer model to a broader range of wavelengths and physical quantities. We find strongly contrasting solutions for the spatial distribution of the radiation fields for disks, thin disks and bulges, which are also strongly dependent on dust opacity, and wavelength. We give an analytic formula for the optically thin case of an infinitely thin disk, which we show well approximates the solutions obtained for the thin disk at longer optical wavelengths. For bulges we find a strong dependence of the radiation fields on Sersic index. Consequently, we show that dust heating in the central regions of galaxies with different bulge Sersic indices can vary by more than a factor of 10.
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http://arxiv.org/abs/1305.0232
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