We investigate the dynamics of charged spinning test particles in the spacetime of a magnetized Bocharova-Bronnikov-Melnikov-Bekenstein black hole (BH), an extremal solution of the Einstein-Maxwell-conformally coupled scalar field equations. Using the Mathisson-Papapetrou-Dixon equations, we derive the equations of motion that incorporate spin-curvature coupling and electromagnetic interactions due to the particle’s charge and an external magnetic field. The effective potential formalism is employed to analyze stable circular orbits, the innermost stable circular orbit (ISCO), and the superluminal bound, ensuring timelike motion. The influence of the particle’s spin <italic>s</italic>, a magnetic coupling parameter <italic>&#969;<inf>B</inf></italic>, is examined numerically, revealing significant shifts in the ISCO radius, specific angular momentum, and energy due to spin and electromagnetic effects. We further study particle collisions near the event horizon, computing the critical angular momentum and center-of-mass energy, which exhibit enhancements akin to the Ba&#241;ados-Silk-West effect, driven by gravitational, electromagnetic, and spin interactions. Our results highlight the intricate interplay of these effects in the BBMB spacetime, offering insights into high-energy astrophysical processes such as accretion disk dynamics and particle acceleration near magnetized BHs.

Uzbekistan

Shokhzod Jumaniyozov

Javlon Rayimbaev

Yunus Turaev

Munisbek Akhmedov

Aybek Seytov

Jamshid Khasanov

Spin effects on motion of charged particles around magnetized black holes in conformally coupled scalar fields

This study examines the dynamical evolution of self-gravitating systems in the presence of exotic matter within the framework of $\textit{f}$($\textit{R}$) gravity. Specifically, we have adopted the Starobinsky model $$f(R) = R + \alpha R^2$$ , which incorporates higher-order curvature corrections to describe nonlinear gravitational behavior. The analysis focuses on the nonlinear spherical evolution of anisotropic matter configurations and explains how dark matter influences their physical characteristics. The presence of dark matter is found to significantly affect the radial and tangential pressure distributions, thereby altering the overall dynamics of the system. The model is employed for compact object $$ Her~X-1$$ described by the generalized Tolman–Kuchowicz metric, demonstrating a singularity-free behavior of the physical parameters. The results reveal that increasing the parameter $\textit{n}$ of the generalized Tolman–Kuchowicz metric leads to striking variations in the model characteristics, highlighting its essential role in governing internal structure and evolution of the compact object. The model remains physically viable under different testing criteria like energy conditions, hydrostatic equilibrium condition, adiabatic index, causality conditions, Herrera’s Cracking condition and mass-radius relation presented in this work.

Czechia

Pakistan

A. Zahra

Azerbaijan

S. Mardan

Jordan

Muhammad Riaz

Inomjon Ibragimov

Erkaboy Davletov

Nonlinear evolution of anisotropic matter configurations under higher-order curvature corrections

In this study, we investigate the electromagnetic field properties of a rotating charged black hole (BH) within the Kalb–Ramond gravity, as well as the circular motion and collisions of test charged particles in the spacetime of the BH. First, the static solutions of the Kalb–Ramond BH are derived using modified Einstein field equations and Maxwell’s equations to obtain the anisotropic solutions of the charged Kalb–Ramond BH. Then, using the Janis–Newman formalism, the exact solutions of the rotating Kalb–Ramond BH are obtained from the static metric. Subsequently, we investigate the horizon properties of the resulting rotating BH. It is shown that all the BH parameters charge and rotation, together with the Kalb–Ramond field, cause the horizon to extend, thereby providing additional gravitational mass. Then, we derive expressions for non-zero components of electromagnetic field configurations with respect to a zero angular momentum observer around the BHs. We also explore the circular motion of charged test particles, determining their effective potential and innermost stable circular orbits (ISCOs), which are influenced by the interplay of gravitational, rotational, and electromagnetic forces. Furthermore, we examine high-energy collisions of charged particles near the event horizon, computing the center-of-mass energy and demonstrating its enhancement by the Kalb–Ramond parameter and BH charge. Our results highlight the potential of charged rotating Kalb–Ramond BHs as natural particle accelerators, offering insights into extreme gravitational and electromagnetic phenomena with implications for astrophysics and theoretical physics.

Bakhrom Abdulazizov

Sherzod Djumanov

Rotating charged black holes in Kalb–Ramond gravity: electromagnetic fields, circular motion and collisions of charged particles