A central gravitational redshift model for the absorption redshift systems in quasi-stellar objects

Abstract

Static, spherically symmetric configurations of core and envelope type have been considered in General Relativity as central gravitational redshift models for the quasi-stellar objects (QSOs) and an attempt has been made to explain the observed absorption features in the QSO spectra on the basis of these models. It is argued that the absorption systems occur in thin shells of densities negligible as compared to the typical densities of the model. The effect of radiation pressure due to a small central source of luminosity on such shells has been investigated and it has been shown that stable equilibrium positions are possible due to a balance between the gravitational and radiation forces. For the QSOs in which the absorption redshift exceeds the emission redshift, models with collapsing absorbing shells have been suggested. Finally some illustrative calculations have been done for the QSO PHL 938 and some other QSOs.