A robust method for investigating galactic evolution in the submillimetre waveband -- II. The submillimetre background and source counts

This is the second of two papers describing a model of galactic evolution in the submillimetre waveband. The model incorporates a self-consistent treatment of the evolution of dust and stars, is normalized to the submillimetre properties of galaxies in the local Universe, and can be used to make predictions for both disc and elliptical galaxies and for 'closed-box', 'inflow', and 'outflow' models of galactic evolution. The model does not include the effects of hierarchical clustering, but we show that the variation in the predictions produced by the different dust-evolution models is so large that it is premature to include the effects of an even more uncertain process. In Paper I we investigated whether it is possible to explain the extremely high dust masses of high-redshift quasars and radio galaxies by galactic evolution. In this paper we use the model to make predictions about the submillimetre background and source counts.