Source with Nonzero Radial Pressure for the Vaidya Metric

Abstract

A null fluid with radial “pressure” is proposed as a source generating Vaidya spacetime. The fluid is anisotropic with no transversal pressures and p = ρ/3 as its equation of state, where p is the isotropic pressure and ρ is the energy density. The radial energy flux is directed inward when \(\dot{m} > 0\) and the total energy flow crossing a surface of constant r resembles the Brown–York quasilocal energy (QLE). A modified Vaidya metric removes the singularity at the origin, and the corresponding QLE is investigated in terms of both r and the mass m(v) of the object.