arXiv subjects

Malick Sallah

Publications and source records attributed to Malick Sallah.

3 recordsLinked to original sources

arXiv2026

Regular Bardeen Black Hole Solutions in Rastall Theory: A Gravitational Decoupling Approach

This research applies the generalized technique of gravitational decoupling to the Bardeen black hole, producing novel black hole solutions in the context of Rastall theory. We proceed by decomposition of the field equations corresponding to an additional matter source into two sets, for further considerations. The metric functions of the Bardeen black hole are adopted to specify the first set. The second one, which is subject to an extra source, is resolved considering a linear equation of state of matter. Through the integration of the solutions of these sets, we develop two expanded models and conduct an in-depth analysis of their distinct physical characteristics, governed by specific parameters. We investigate thermodynamic quantities like density, anisotropic pressure, energy bounds, asymptotic flatness, and thermodynamical properties like the Hawking temperature, entropy, and specific heat, etc. Both models are asymptotically flat but violate the energy bounds. Furthermore, the density, radial pressure, and Hawking temperature demonstrate consistent and acceptable behavior. Ultimately, the thermodynamic stability is affirmed through the analysis of specific heat and the Hessian matrix.

gr-qc↗

arXiv2025

Investigating Strange Stars in Rastall Theory

This study explores the structural formation of various spherically symmetric anisotropic stars within the framework of Rastall theory. To achieve this, we derive modified field equations which are then resolved using the Finch-Skea ansatz, which involve unknown parameters $(A_1,A_2,A_3)$. These parameters are found by using appropriate constraints given by the junction conditions, in addition to observational data from some selected stars. The $\mathbb{EOS}$ given by the $\mathbb{MIT}$ bag model is employed to examine the interior structure and various physical properties of these compact objects. For calculated values of the bag constant $\mathcal{B}$ and two values of the Rastall parameter, $\xi = 0.3, 0.5$, we investigate the regularity and viability of the state variables. Additionally, we analyze stability of the developed model by employing three distinct criteria. We find that the obtained model is stable and provides an accurate approximation for the mass and radius of strange stars when the Rastall parameter $\xi = 0.3$ is considered.

gr-qc↗

arXiv2025

Extended Black Hole Solutions in Rastall Theory of Gravity

We utilize the gravitational decoupling via the extended geometric deformation to extend the Schwarzschild vacuum solution to new black holes in Rastall theory. By employing linear transformations that deform both the temporal and radial coefficients of the metric, the field equations with a dual matter source are successfully decoupled into two sets. The first of these sets is described by the metric for the vacuum Schwarzschild spacetime, while the second set corresponds to the added extra source. Three extended solutions are obtained using two restrictions on the metric potentials and extra source, respectively. For selected values of the Rastall and decoupling parameters, we study the impact of the fluctuation of these parameters on the obtained models. We also investigate the asymptotic flatness of the resulting spacetimes by analysis of the metric coefficients. Finally, the nature of the additional source is explored for each model, via analysis of the energy conditions. It is found among other results that none of the obtained models satisfy the energy conditions, while only the model corresponding to the barotropic equation of state mimics an asymptotically flat spacetime.

gr-qc↗