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 QSO_s. 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 QSO_s, 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.