V. D. Ivashchuk, A. N. Malybayev, G. S. Nurbakova, G. Takey
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引用次数: 0
Abstract
Dilatonic dyon-like black hole solutions with two (color) charges \(Q_{1}\) and \(Q_{2}\) (electric and magnetic ones) are considered in a gravitational 4D model with two scalar fields and two 2-forms. Two-dimensional dilatonic coupling vectors \(\vec{\lambda}_{i}\), \(i=1,2\), determining the model, obey the relation \(\vec{\lambda}_{1}\vec{\lambda}_{2}=1/2\). Circular null geodesics in the field of such black holes are explored. The master equation for the photon sphere radius \(R\) is derived. A conjecture is suggested on the existence and uniqueness of the solution to the master equation with \(R>R_{g}\), where \(R_{g}\) is the horizon radius. This conjecture is varified for certain special cases, e.g., for a charge symmetric configuration: \(Q_{1}^{2}=Q_{2}^{2}\). In this charge symmetric case, we present a relation for the spectrum of quasinormal modes of a test massless scalar field in the eikonal approximation, and an example of circular orbits of a massive particle.
期刊介绍:
Gravitation and Cosmology is a peer-reviewed periodical, dealing with the full range of topics of gravitational physics and relativistic cosmology and published under the auspices of the Russian Gravitation Society and Peoples’ Friendship University of Russia. The journal publishes research papers, review articles and brief communications on the following fields: theoretical (classical and quantum) gravitation; relativistic astrophysics and cosmology, exact solutions and modern mathematical methods in gravitation and cosmology, including Lie groups, geometry and topology; unification theories including gravitation; fundamental physical constants and their possible variations; fundamental gravity experiments on Earth and in space; related topics. It also publishes selected old papers which have not lost their topicality but were previously published only in Russian and were not available to the worldwide research community