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In this paper, we report on a study of the anisotropic strange stars under Finsler geometry. Keeping in mind that Finsler spacetime is not merely a generalization of Riemannian geometry rather the main idea is the projectivized tangent bundle of the manifold 𝕄 , we have developed the respective field equations. Thereafter, we consider the strange quark distribution inside the stellar system followed by the MIT bag model equation-of-state (EoS). To find out the stability and also the physical acceptability of the stellar configuration, we perform in detail some basic physical tests of the proposed model. The results of the testing show that the system is consistent with the Tolman–Oppenheimer–Volkoff (TOV) equation, Herrera cracking concept, different energy conditions and adiabatic index. One important result that we observe is, the anisotropic stress reaches the maximum at the surface of the stellar configuration. We calculate (i) the maximum mass as well as the corresponding radius, (ii) the central density of the strange stars for finite values of bag constant B g and (iii) the fractional binding energy of the system. This study shows that Finsler geometry is especially suitable to explain massive stellar systems. [ABSTRACT FROM AUTHOR]

This paper discusses a generalized model for compact stars, assumed to be anisotropic in nature due to the presence of highly dense and ultra-relativistic matter distribution. After embedding the 4D Riemannian space locally and isometrically into a 5D pseudo-Euclidean space, we solve the Einstein equations by employing a class of physically acceptable metric functions. The physical properties determined include the anisotropic factor showing that the anisotropy is zero at the center and maximum at the surface. Other boundary conditions yield the values of various parameters needed for rendering the numerous plots and also led to the EOS parameters. It is further determined that the usual energy conditions are satisfied and that the compact structures are stable, based on several criteria, viz., the equilibrium of forces, Herrera cracking concept, adiabatic index, etc. We note that the proposed stellar model satisfies the Buchdahl condition. Finally, the values of the numerous constants and physical parameters are determined, specifically for the compact stellar object LMC X − 4 , which we choose as a representative of the compact stars to present the analysis of the obtained results. Finally, we show that the present generalized model can justify most of the compact stars including white dwarfs and ultra-dense compact stars for a suitable tuning of the parametric values of n. [ABSTRACT FROM AUTHOR]

We present a family of relativistic fluid spheres using the Karmarkar criterion along with the Pandey–Sharma condition. Ranges of n and m for well-behaved solutions depend on the mass and radius of the compact star model. As an example, we have chosen Vela X-1 (M = 1. 7 7 M ⊙ , R = 9. 5 6 km) for complete analysis of the solutions. For the same star, the well-behaved ranges are 1 < n < 5 and 3 < m < 1 3. However, beyond these limits, either the transversal sound speed becomes imaginary or violates the causality principle. Further, the critical part of our solution is that corresponding to every nonzero positive even value of m yields zero values of all the physical quantities. [ABSTRACT FROM AUTHOR]

In this paper, we present a strange stellar model using Tolman V-type metric potential employing simplest form of the MIT bag equation of state (EOS) for the quark matter. We consider that the stellar system is spherically symmetric, compact and made of an anisotropic fluid. Choosing different values of n we obtain exact solutions of the Einstein field equations and finally conclude that for a specific value of the parameter n=1/2, we find physically acceptable features of the stellar object. Further, we conduct different physical tests, viz., the energy condition, generalized Tolman–Oppeheimer–Volkoff (TOV) equation, Herrera’s cracking concept, etc., to confirm the physical validity of the presented model. Matching conditions provide expressions for different constants whereas maximization of the anisotropy parameter provides bag constant. By using the observed data of several compact stars, we derive exact values of some of the physical parameters and exhibit their features in tabular form. It is to note that our predicted value of the bag constant satisfies the report of CERN-SPS and RHIC. [ABSTRACT FROM AUTHOR]

Colloidal systems are often modeled as fluids of hard particles (possibly with an additional soft attraction, e.g. caused by polymers also contained in the suspension). In simulations of such systems, the virial theorem cannot be straightforwardly applied to obtain the components of the pressure tensor. In systems confined by walls, it is hence also not straightforward to extract the excess energy due to the wall (the 'wall tension') from the pressure tensor anisotropy. A comparative evaluation of several methods to circumvent this problem is presented, using as examples fluids of hard spheres and the Asakura-Oosawa model of colloid-polymer mixtures with a size ratio q = 0.15 (for which the effect of the polymers can be integrated out to yield an effective attractive potential between the colloids). Factors limiting the accuracy of the various methods are carefully discussed, and controlling these factors very good mutual agreement between the various methods is found. [ABSTRACT FROM AUTHOR]