Long-wavelength absorption by fractal dust grains

The far-infrared and submillimeter absorption properties of random aggregates of conducting spheres have been studied as a possible source for the long-wavelength absorption of interstellar dust grains. The complex shapes of random aggregates have various fractal dimensions, depending on the process that forms them. The absorption cross section σ versus frequency ν of these fractal grains can follow a power law σ ∝ ν with 0.6 < α < 1.4 for two decades in frequency. The long wavelength absorption versus frequency is affected more by the shape of a conducting grain than by its composition.