arXiv subjects

Ayesha Almas

Publications and source records attributed to Ayesha Almas.

3 recordsLinked to original sources

arXiv2026

Charged Anisotropic Compact Stars in $f(R,ϕ,X)$ Gravity: A Class I Embedding Approach with Reissner-Nordström Exterior

This work examines the physical characteristics of charged, anisotropic compact spheres within the framework of $f(R,ϕ,X)$ modified gravity. Starting from a static, spherically symmetric spacetime, we employ an Adler-type ansatz for the temporal metric component $g_{tt}$. The corresponding radial metric component $g_{rr}$ is then systematically derived through application of the Karmarkar condition, which ensures a class-one embedding for the interior geometry. A crucial aspect of our approach involves matching the interior solution at the stellar boundary to the exterior Reissner--Nordstr$\ddot{0}$m spacetime---the established vacuum solution for charged, non-rotating masses. This matching procedure is essential for determining integration constants and verifying global physical consistency. Our comprehensive analysis of the resulting stellar model investigates multiple physical aspects, including energy density, radial and tangential pressures, anisotropy, equation-of-state parameters, energy conditions, mass function, compactness, and surface redshift. Stability assessment further incorporates examination of the adiabatic index and the Tolman--Oppenheimer--Volkoff equation. Collectively, our findings demonstrate that the charged compact star model presented here constitutes a physically viable configuration---free of singularities and maintaining stable equilibrium across the considered parameter space.

physics.gen-ph↗

arXiv2024

Impact of Ricci Inverse Gravity on Hybrid Star Model

The objective of our current study is to explore novel aspects of a stationary anisotropic relativistic hybrid compact star that consists of quark matter (QM) in its core and ordinary baryonic matter (OBM) in its crust. This study has been done by adopting separate equations of states (EoSs) for quark matter and baryonic matter. The MIT bag model equation of state $p_{q}=\frac{1}{3}(ρ_{q}-4B)$ has been used to demonstrate a correlation between the density and pressure of weird quark matter in the interior of the star. In addition, we present a simple linear equation of state $p_{r}=β_{1}ρ-β$ that links radial pressure and matter density for OBM. The stellar model was formulated within the context of $f(\mathcal{R},\mathcal{A})$ gravity, utilizing a linear correlation between Ricci tensor $\mathcal{R}$ and anticurvature scaler $\mathcal{A}$.To solve the field equations of this novel alternative gravity, we employ the Krori and Barua approach to the metric potentials. The validity of our suggested model is assessed using the graphical approach, while ensuring that the conditions are physically feasible. Our focus is specifically on the tiny celestial object known as LMC X-4 [$\text{M} = (1.04^{+0.09}_{-0.09})M_{\odot};\text{R}=8.301^{+0.2}_{-0.2}\text{km}$], which we consider a viable candidate for a strange quark star. We want to clarify the model's physical validity by examining a variety of physical assessments, including dynamical equilibrium, energy conditions, compactness factor, mass function, and surface redshift. The resulting outcome confirms the authenticity of the hybrid star model under analysis.

gr-qc↗

arXiv2024

Anisotropic Spheres Via Embedding Approach in $f(R,ϕ, X)$ Gravity

In this manuscript, we investigate the behavior of stellar structure through embedding approach in $f(R, ϕ, X)$ modified theory of gravity, where $R$ denotes the Ricci scalar, $ϕ$ represents the scalar potential and $X$ indicates the kinetic potential. For this purpose, we consider the spherically symmetric space-time with anisotropic fluid. We further choose three different stars i.e. LMC X-4, Cen X-3, and EXO 1785-248 to demonstrate the behavior of stellar structures. We further compare the Schwarzschild space-time as exterior geometry with spherically symmetric space-time to calculate the values of unknown parameters. In this regard, we investigate the graphical features of stellar spheres such es energy density, pressure components, anisotropic component, equation of state parameters, stability analysis and energy conditions. Furthermore, we investigate some extra conditions such as mass function, compactness factor and surface redshift respectively. Conclusively, all the compact stars under observations are realistic, stable, and are free from any physical or geometrical singularities. We find that the embedding class one solution for anisotropic compact stars is viable and stable.

gr-qc↗