Central gravitational redshifts from static massive objects

Abstract

The possibility of obtaining high gravitational redshifts from static massive objects is investigated in an attempt towards finding a satisfactory explanation of the redshifts of the QSOs. Following Bondi's approach, equilibrium configurations of the core and envelope type are discussed within the framework of general relativity. Gravitational redshifts from the center of the core, from the core-envelope boundary, and from the surface of the object are calculated in a variety of cases, and their dependence on the equation of state is studied. In a possible application of these models to QSOs, the emission is considered to arise from an optically thin central region surrounded by an exterior which lets through a fraction of the emitted light. The mass of such an object can be estimated from the emission line data, as discussed with the example of 3C9.