arXiv subjects

O. Gurtug

Publications and source records attributed to O. Gurtug.

22 records · Page 2Linked to original sources

arXiv2010

Dilatonic interpolation between Reissner-Nordstrom and Bertotti-Robinson spacetimes with physical consequences

We give a general class of static, spherically symmetric, non-asymptotically flat and asymptotically non-(anti) de Sitter black hole solutions in Einstein-Maxwell-Dilaton (EMD) theory of gravity in 4-dimensions. In this general study we couple a magnetic Maxwell field with a general dilaton potential, while double Liouville-type potentials are coupled with the gravity. We show that the dilatonic parameters play the key role in switching between the Bertotti-Robinson and Reissner-Nordström spacetimes. We study the stability of such black holes under a linear radial perturbation, and in this sense we find exceptional cases that the EMD black holes are unstable. In continuation we give a detailed study of the spin-weighted harmonics in dilatonic Hawking radiation spectrum and compare our results with the previously known ones. Finally, we investigate the status of resulting naked singularities of our general solution when probed with quantum test particles.

gr-qc↗

arXiv2009

Generating Static Spherically Symmetric Black-holes in Lovelock Gravity

Generalization of a known theorem to generate static, spherically symmetric black-hole solutions in higher dimensional Lovelock gravity is presented. Particular limits, such as Gauss-Bonnet (GB) and/or Einstein-Hilbert (EH) in any dimension $N$ yield all the solutions known to date with an energy-momentum. In our generalization, with special emphasis on the third order Lovelock gravity, we have found two different class of solutions characterized by the matter field parameter. Several particular cases are studied and properties related to asymptotic behaviours are discussed. Our general solution which covers topological black holes as well, splits naturally into distinct classes such as Chern-Simon (CS) and Born-Infeld (BI) in higher dimensions. The occurence of naked singularities are studied and it is found that, the spacetime behaves nonsingular in quantum mechanical sense when it is probed with quantum test particles. The theorem is extended to cover Bertotti-Robinson (BR) type solutions in the presence of the GB parameter alone. Finally we prove also that extension of the theorem for a scalar-tensor source of higher dimensions $(N>4)$ fails to work.

gr-qc↗

arXiv2003

New Singular and Nonsingular Colliding Wave Solutions in Einstein - Maxwell - Scalar Theory

A technique is given to generate coupled scalar field solutions in colliding Einstein - Maxwell (EM) waves. By employing the Bell - Szekeres solution as seed and depending on the chosen scalar field it is possible to construct nonsingular solutions. If the original EM solution is already singular addition of scalar fields does not make the physics any better. In particular, scalar field solution that is transformable to spherical symmetry is plagued with singularities.

gr-qc↗

arXiv2002

Failure of a Stability Conjecture in General Relativity

By employing an exact back-reaction geometry, Helliwell-Konkowski stability conjecture is shown to fail. This happens when a test null dust is inserted to the interaction region of cross-polarized Bell-Szekeres spacetime.

gr-qc↗