arXiv subjects

M. Haluk Seçuk

Publications and source records attributed to M. Haluk Seçuk.

4 recordsLinked to original sources

arXiv2026

Straight and Wiggly Cosmic Strings in Horndeski Theory

In this article, the behavior of a straight cosmic string is studied for the linearized version of Horndeski theory in cases where the scalar field is massless or massive. Several physical properties of such solutions are discussed in detail regarding the effects of the scalar field of this theory. The mass of the scalar field induces a screening effect such that, in the massive theory, the string solution approaches to the general relativistic one. We also consider wiggly cosmic strings, obtain the solutions for both massless and massive cases, discuss their properties and observe similar screening effects.

gr-qc↗

arXiv2025

Innermost stable circular orbits around a Reissner-Nordström-global monopole spacetime in a homogeneous magnetic field

We investigate the dynamics of charged particles in the spacetime of a global monopole swallowed by a Reissner-Nordström (RN) black hole in the presence of an external, weak, asymptotically homogeneous magnetic field. We carefully analyze and deduce the conditions to have such a magnetic field around this black hole and show that this is indeed possible in the small but nontrivial charge and monopole term limit. We obtain the general equations of motion and analyze them for special cases of circular orbits, focusing on the innermost stable circular orbit (ISCO) of this configuration. The richness of the parameters and complicated forms of the resulting equations of motion necessitate a numerical approach. Hence, we have presented our results with numerous graphs, which help to understand the evolution of ISCO as a function of the external test magnetic field and the monopole term, depending on the parameters of the black hole, such as its electric charge, as well as the properties of the test particle, such as its specific charge, angular momentum, and energy. We have also analyzed the effective potential that these fields generate and deduced results for the aforementioned values of the external and internal parameters of the spacetime.

gr-qc↗

arXiv2020

Bending of Light from Reissner-Nordström-de Sitter-Monopole Black Hole

We study light deflection from a Reissner-Nordström-de Sitter black hole in the gravitational monopole background. We first calculate the orbit equation and the contribution of the monopole and black hole parameters to the deflection angle up to second-order for the vanishing cosmological constant case using the Rindler-Ishak method. We also obtain the contribution of the cosmological constant to light deflection in this geometry in the weak field limit using the same method.

gr-qc↗

arXiv2020

Superradiance of a Global Monopole in Reissner-Nordström(-AdS) Space-time

In this article, the behaviour of a charged and massive scalar field around a global monopole swallowed by a Reissner-Nordström-Anti-de Sitter (RN-AdS) black hole is investigated by considering the Klein-Gordon equation in this geometry. The superradiance phenomenon and instability behaviour of the black hole against charged scalar perturbations are studied for both an RN-AdS case and also for an RN black hole surrounded by a reflective mirror, i.e., the black hole bomb case. The effects of the monopole on these cases are discussed analytically and also with the help of several graphs in detail. The monopole charge affects the superradiance threshold frequency and also effects the instability time scale for both cases. The existence of global monopole makes these black holes more stable against superradiance instability.

gr-qc↗