中心密度依赖各向异性致密星

Physical Attributes of Anisotropic Compact Stars in $f(R,G)$ Gravity

Modified gravity is one of the potential candidates to explain the accelerated expansion of the universe. Current study highlights the materialization of anisotropic compact stars in the context of $f(R,G)$ theory of gravity. In particular, to gain insight in the physical behavior of three stars namely, Her $X1$, SAX J $1808$-$3658$ and 4U $1820$-$30$, energy density, and radial and tangential pressures are calculated. The $f(R,G)$ gravity model is split into a Starobinsky like $f(R)$ model and a power law $f(G)$ model. The main feature of the work is a $3$-dimensional graphical analysis in wh…

Anisotropic compact stars in Karmarkar spacetime

We present a new class of solutions to the Einstein field equations for an anisotropic matter distribution in which the interior space-time obeys the Karmarkar condition. The necessary and sufficient condition required for a spherically symmetric space-time to be of class one reduces the gravitational behavior of the model to a single metric function. By assuming a physically viable form for the $g_{rr}$ metric potential we obtain an exact solution of the Einstein field equations which is free from any singularities and satisfies all the physical criteria. We utilize this solution to predict t…

Anisotropic Compact Star Model Satisfying Karmarkar Conditions

A new class of solutions describing the composition of compact stars has been proposed, assuming that the fluid distribution inside the star is anisotropic. This is achieved by assuming the appropriate metric potential and then solving Einstein's field equations using Karmarkar conditions [Karmarkar K. R., \textit{Proc. Indian Acad. Sci.} \textbf{27} (1948) 56] to derive the expressions for star density, the radial and tangential pressures in terms of the constants A, B, a paramter `a' and the curvature parameter R. The equations thus obtained have been passed through rigorous conditional anal…

Anisotropic Compacts Stars on Paraboloidal Spacetime with Linear Equation of State

New exact solutions of Einstein's field equations (EFEs) by assuming linear equation of state, $ p_r = α(ρ- ρ_R) $ where $ p_r $ is the radial pressure and $ ρ_R $ is the surface density, are obtained on the background of a paraboloidal spacetime. By assuming estimated mass and radius of strange star candidate 4U 1820-30, various physical and energy conditions are used for estimating the range of parameter $ α$. The suitability of the model for describing pulsars like PSR J1903+327, Vela X-1, Her X-1 and SAX J1804.3658 has been explored and respective ranges of $ α$, for which all physical and…

Anisotropic Compact Stars in $f(T)$ Gravity

This paper deals with the theoretical modeling of anisotropic compact stars in the framework of $f(T)$ theory of gravity, where $T$ is torsion scalar. To this end, we have used the exact solutions of Krori and Barua metric to a static spherically symmetric metric. The unknown constants involved in the Krori and Barua metric have been specified by using the masses and radii of compact stars 4$U$1820-30, Her X-1, SAX J 1808-3658. The physical properties of these stars have been analyzed in the framework of $f(T)$ theory. In this setting, we have checked the anisotropic behavior, regularity condi…

A new model for spherically symmetric anisotropic compact star

In this article we obtain a new anisotropic solution for Einstein's field equation of embedding class one metric. The solution is representing the realistic objects such as $Her~X-1$ and $RXJ~1856-37$. We perform detailed investigation of both objects by solving numerically the Einstein field equations under with anisotropic pressure. The physical features of the parameters depend on the anisotropic factor i.e. if anisotropy is zero everywhere inside the star then the density and pressures will become zero and metric turns out to be flat. We report our results and compare with the above mentio…

Analytic models of Anisotropic Strange Stars in $f(T)$ Gravity with Off-diagonal tetrad

This paper is devoted to study the analytic models of anisotropic compact stars in $f(T)$ gravity (where $T$ is torsion scalar), with non-diagonal tetrad. By taking the anisotropic source inside the spherically symmetric star, the equations of motions have been derived in the context of $f(T)$ gravity. Krori and Barua metric which satisfies the physical requirement of a realistic star, has been applied to describe the compact objects like strange stars. We use the power law form of $f(T)$ model to determine explicit relations of matter variables. Further, we have found the anisotropic behavior…

f(R,ϕ,X)引力下的带电各向异性致密星：采用赖斯纳-诺德斯特龙外解的I类嵌入方法

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

本文在f(R,ϕ,X)引力框架下，采用I类嵌入方法结合Reissner-Nordström外解构建带电各向异性致密星模型，验证其物理可行性与稳定性。

A generalized family of anisotropic compact object in general relativity

We present model for anisotropic compact star under the general theory of relativity of Einstein. In the study a 4-dimensional spacetime has been considered which is embedded into the 5-dimensional flat metric so that the spherically symmetric metric has class 1 when the condition $e^λ=\left(\,1+C\,e^ν \,{ν'}^2\,\right)$ is satisfied ($λ$ and $ν$ being the metric potentials along with a constant $C$). A set of solutions for the field equations are found depending on the index $n$ involved in the physical parameters. The interior solutions have been matched smoothly at the boundary of the spher…

A study of anisotropic spheres in $f(Q)$ gravity with quintessence field

This manuscript examines the compact stars in gravity $f (Q)$, where non-metricity $Q$ drives gravitational interactions. To achieve this goal, we consider a spherically symmetric spacetime with the anisotropic fluid distribution. In particular, the quintessence field is used in the energy-momentum tensor to explore the solution of compact stars. In addition, we select three specific types of compact stars, namely HerX-1, SAXJ1808.4-3658, and 4U1820-30. We develop the field equations using the quintessence field of a specific form of $f(Q)$ as $f(Q)=Q-αγ\left(1-\frac{1}{e^{\frac{Q}γ}}\right)$ …