Browsing by Subject "Killing vector fields"

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    Characterizing killing vector fields of standard static space-times
    (Elsevier, 2012) Dobarro, F.; Ünal, B.
    We provide a global characterization of the Killing vector fields of a standard static space-time by a system of partial differential equations. By studying this system, we determine all the Killing vector fields in the same framework when the Riemannian part is compact. Furthermore, we deal with the characterization of Killing vector fields with zero curl on a standard static space-time. © 2011 Elsevier B.V..
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    Sequential warped products: curvature and conformal vector fields
    (University of Nis, 2019) Chand De, Uday; Shenawy, S.; Ünal, Bülent
    In this note, we introduce a new type of warped products called as sequential warped products to cover a wider variety of exact solutions to Einstein’s field equation. First, we study the geometry of sequential warped products and obtain covariant derivatives, curvature tensor, Ricci curvature and scalar curvature formulas. Then some important consequences of these formulas are also stated. We provide characterizations of geodesics and two different types of conformal vector fields, namely, Killing vector fields and concircular vector fields on sequential warped product manifolds. Finally, we consider the geometry of two classes of sequential warped product space-time models which are sequential generalized Robertson-Walker space-times and sequential standard static space-times.