3D dust radiative transfer simulations in the inhomogeneous interstellar medium

Observations have shown that the interstellar medium is strongly non-homogeneous. We present an extensive set of 3D radiative transfer simulations in an inhomogeneous interstellar medium. We consider a two-phase interstellar medium, consisting of a smooth dust component and an additional clumpy component. We have run simulations in typical galactic and circumstellar environments and adopt a range of clump sizes, dust filling factors and contrasts between the smooth and clumpy components. We investigate in detail the effect of the clumpiness of the interstellar dust component on the attenuation of the stellar radiation, the temperature distribution of the dust and the resulting far-infrared emission. We find that, for modest optical depths, the dust temperature distribution and the far-infrared emission are rather insensitive to dust inhomogeneities, while the optical emission can be significantly affected by dust clumping. For higher optical depths, as typically in circumstellar or prestellar clouds, the effects are strongly dependent on the applied clumping parameters. Therefore, the inhomogeneous nature of the interstellar medium should always be taken into account in radiative transfer calculations in starforming environments.