On some curvature properties of Vaidya–Bonner metric

The Vaidya–Bonner metric is a non-static generalization of Reissner–Nordström metric and this paper deals with the investigation of the curvature restricted geometric properties of such a metric. The scalar curvature vanishes and several pseudosymmetric-type curvature conditions are fulfilled by this metric. Also, it is a [Formula: see text]-quasi-Einstein, [Formula: see text] and generalized Roter type manifold. As a special case, the curvature properties of Reissner–Nordström metric are obtained. It is noted that Vaidya–Bonner metric admits several generalized geometric structures in comparison to Reissner–Nordström metric and Vaidya metric.

Gravitational collapse for the K-essence emergent Vaidya spacetime

In this paper, we study the gravitational collapse in the k-essence emergent gravity using a generalized Vaidya-type metric as a background. We also analyze the cosmic censorship hypothesis for this system. We show that the emergent gravity metric resembles closely to the new type of the generalized Vaidya metrics for null fluid collapse with the k-essence emergent mass function, where we consider the k-essence scalar field being a function solely of the advanced or the retarded time. This new type of k-essence emergent Vaidya metric has satisfied the required energy conditions. The existence of the locally naked central singularity, the strength and the strongness of the singularities for the k-essence emergent Vaidya metric are the interesting outcomes of the present work.

Embedding with Vaidya geometry

The Vaidya metric is important in describing the exterior spacetime of a radiating star and for describing astrophysical processes. In this paper we study embedding properties of the generalized Vaidya metric. We had obtained embedding conditions, for embedding into 5-dimensional Euclidean space, by two different methods and solved them in general. As a result we found the form of the mass function which generates a subclass of the generalized Vaidya metric. Our result is purely geometrical and may be applied to any theory of gravity. When we apply Einstein’s equations we find that the embedding generates an equation of state relating the null string density to the null string pressure. The energy conditions lead to particular metrics including the anti/de Sitter spacetimes.

Radiating-collapsing models satisfying Karmarkar condition

This paper presents a class of exact spherical symmetric solutions of the Einstein equations admitting heat-conducting anisotropic fluid as a collapsing matter. The exterior spacetime is assumed to be the Vaidya metric. This class of solutions is shown to satisfy all the energy conditions throughout the interior of the star, and the luminosity is time independent, radiating uniformly throughout the collapse.