An Idealized Model for Dust Accretion in Active Galactic Nuclei

Abstract

With an adequate supply of matter, the inwards drifting of dust particles induced by the Poynting-Robertson effect can lead to the formation of a shell or disk-like structure around the source of radiation. In a steady state, the Poynting-Robertson effect produce a spatial density of dust going like l/r which in turn give rise to a mid-infrared spectrum F_ν∝l/ν. We think that this short report could be of interest for the interpretation of the infrared excess found in many extragalactic sources.