arXiv subjects

D. M. Pandya

Publications and source records attributed to D. M. Pandya.

13 recordsLinked to original sources

arXiv2025

Relativistic compact object in Generalised Tolman-Kuchowicz spacetime with quadratic equation of state

This paper presents the class of solutions to the Einstein field equations for the uncharged static spherically symmetric compact object PSR J0952-0607 by using Generalized Tolman-Kuchowicz space-time metric with quadratic equation of state. We have obtained the bound on the model parameter n graphically and achieved the stable stellar structure of the mathematical model of a compact object. The stability of the generated model is examined by the Tolman-Oppenheimer-Volkoff equation and the Harrison-Zeldovich-Novikov criterion. This anisotropic compact star model fulfills all the required stability criteria including the causality condition, adiabatic index, and Buchdahl condition, Herrera's cracking condition and pertains free from central singularities.

gr-qc↗

arXiv2023

Generalized Finch and Skea model compatible with observational data

We present an entirely new class of solutions to Einstein's field equations that correspond to a static spherically symmetric anisotropic system by generalizing the Finch and Skea ansatz using the linear equation of state for the gravitational potential $g_{rr} $. Based on physical requirements, regularity condition, and stability, we make various assumptions about the model's parameters. The exact solution generates a plausible model of a compact star PSR J0348+0432 that satisfies all physical criteria. The requirements for a well-behaved compact star are met, including regularity, equilibrium, causality, stability, energy, and compactness limitations.

gr-qc↗

arXiv2023

New charged anisotropic solution on paraboloidal spacetime

New exact solutions of Einstein's field equations for charged stellar models by assuming linear equation of state $ P_r=A(ρ-ρ_{a}) $, where $ P_r $ is the radial pressure and $ ρ_{a} $ is the surface density. By assuming $ e^λ = 1+\frac{r^2}{R^2} $ for metric potential. The physical acceptability conditions of the model are investigated, and the model is compatible with several compact star candidates like 4U 1820-30, PSR J1903+327, EXO 1785-248, Vela X-1, PSR J1614-2230, Cen X-3. A noteworthy feature of the model is that it satisfies all the conditions needed for a physically acceptable model.

gr-qc↗

arXiv2020

Finch-Skea Solutions of Anisotropic Stellar Models in $f(R)$ Gravity

Present paper deals with the composition and modelling of compact dense astrophysical bodies under the framework of $f(R)$ gravity. The model is employed on various observed strange stars viz., SMC X-1, SAX J1808.4-3658, Swift J1818.0-1607, PSR J1614-2230 and PSR J0348+0432. Upon setting the appropriate value of dimensionless coupling parameter $λ$, the physical parameters such as the density, the radial and tangential pressures were obtained. Mass-Radius relation without presuming any equation of state is capable enough to accommodate all strange stars nearly having solar mass up to 2.5. The physical viability of the model is examined for all the aforementioned stars and it is found that all the regularity and stability conditions are satisfied.

gr-qc↗

arXiv2019

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 analysis. It is further shown that the model is physically viable and mathematically well-behaved, fulfilling the requisite conditions viz., regularity condition, strong energy condition, causality condition, etc. Observed star candidates including EXO 1785-248, SMC X-1, SAXJ1808.43658(SS2), HER X-1, 4U 1538-52, Cen X-3 and LMC X-4 were found to conform to a good approximation through the outcome of this model for a=0.5.

physics.gen-ph↗

arXiv2017

Models of compact stars on paraboloidal spacetime satisfying Karmarkar condition

A new exact solution of Einstein's field equations on the background of paraboloidal spacetime using Karmarkar condition is reported. The physical acceptability conditions of the model are investigated and found that the model is compatible with a number of compact star candidates like Her X-1, LMC X-4, EXO 1785-248, PSR J1903+327, Vela X-1 and PSR J1614-2230. A noteworthy feature of the model is that it is geometrically significant and simple in form.

physics.gen-ph↗

arXiv2017

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 energy conditions are satisfied throughout the distribution, are obtained.

physics.gen-ph↗

arXiv2016

Charged compact stellar model in Finch-Skea spacetime

In this paper a compact charged stellar model in the Finch and Skea background spacetime [{\it Class. Quantum Gravity} {\bf6}, 467 (1989)] is presented. The model has been developed by assuming a particular charge distribution within the stellar interior. The model is well behaved and can describe a large class of compact stars. Physical features of the model are studied and in particular we show how the presence of charge can have a non-negligible impact on the mass-radius ($M-R$) relationship of such class of stars.

gr-qc↗

arXiv2015

A new class of solutions of compact stars with charged distributions on pseudo-spheroidal spacetime

In this paper a new class of exact solutions of Einstein's field equations for compact stars with charged distributions is obtained on the basis of pseudo-spheroidal spacetime characterized by the metric potential $g_{rr}=\frac{1+K\frac{r^{2}}{R^{2}}}{1+\frac{r^{2}}{R^{2}}}$, where $K$ and $R$ are geometric parameters of the spacetime. The expressions for radial pressure ($ p_r $) and electric field intensity ($ E $) are chosen in such a way that the model falls in the category of physically acceptable one. The bounds of geometric parameter $K$ and the physical parameters $ p_0 $ and $α$ are obtained by imposing the physical requirements and regularity conditions. The present model is in good agreement with the observational data of various compact stars like 4U 1820-30, PSR J1903+327, 4U 1608-52, Vela X-1, SMC X-4, Cen X-3 given by Gangopadhyay {\em{et al.}} [Gangopadhyay T., Ray S., Li X-D., Dey J. and Dey M., {\it Mon. Not. R. Astron. Soc.} {\bf431} (2013) 3216]. When $ α= 0, $ the model reduces to the uncharged anisotropic distribution given by Thomas and Pandya [Thomas V. O. and Pandya D. M.,~arXiv:1506.08698v1 [gr-qc](26 Jun 2015)].

physics.gen-ph↗

arXiv2015

Compact stars on pseudo-spheroidal spacetime compatible with observational data

A new class of solutions for Einstein's field equations representing a static spherically symmetric anisotropic distribution of matter is obtained on the background of pseudo-spheroidal spacetime. We have prescribed the bounds of the model parameters $ k $ and $ p_0 $ on the basis of the elementary criteria for physical acceptability, viz., regularity, stability and energy conditions. By taking the values of model parameters from the prescribed bounds, we have shown that our model is compatible with the observational data of a wide variety of compact stars like 4U 1820-30, PSR J1903+327, 4U 1608-52, Vela X-1, PSR J1614-2230, SMC X-4 and Cen X-3.

gr-qc↗

arXiv2015

A new class of solutions of anisotropic charged distributions on pseudo-spheroidal spacetime

In the present article a new class of exact solutions of Einstein's field equations for charged anisotropic distribution is obtained on the background of pseudo-spheroidal spacetime characterized by the metric potential $g_{rr}=\frac{1+K\frac{r^2}{R^2}}{1+\frac{r^2}{R^2}}$, where $K$ and $R$ are geometric parameters of the spacetime. The radial pressure $p_r$ and electric field intensity $E$ are taken in the form $8πp_r = \frac{K-1}{R^2}\frac{\left(1-\frac{r^2}{R^2} \right)}{\left(1+K\frac{r^2}{R^2} \right)^2}$ and $E^2 = \frac{α(K-1)\frac{r^2}{R^2}}{R^2\left(1+K\frac{r^2}{R^2} \right)^2}$. The bounds of geometric parameter $K$ and the parameter $α$ appearing in the expression of $E^2$ are obtained by imposing the requirements for a physically acceptable model. It is found that the model is in good agreement with the observational data of number of compact stars like 4U 1820-30, PSR J1903+327, 4U 1608-52, Vela X-1, PSR J1614-2230, Cen X-3 given by Gangopadhyay {\em{et al}} [Gangopadhyay T., Ray S., Li X-D., Dey J. and Dey M., {\it Mon. Not. R. Astron. Soc.} {\bf431} (2013) 3216]. When $α= 0$, the model reduces to the uncharged anisotropic distribution given by Ratanpal {\em et al.} [Ratanpal B. S., Thomas V. O. and Pandya D. M., arXiv:1506.08512 [gr-qc](2015)]

gr-qc↗

arXiv2015

Anisotropic Star on Pseudo-Spheroidal Spacetime

A new class of exact solutions of Einstein's field equations representing anisotropic distribution of matter on pseudo-spheroidal spacetime is obtained. The parameters appearing in the model are restricted through physical requirements of the model. It is found that the models given in the present work is compatible with observational data of a wide variety of compact objects like 4U 1820-30, PSR J1903+327, 4U 1608-52, Vela X-1, PSR J1614-2230, SMC X-4, Cen X-3. A particular model of pulsar PSR J1614-2230 is studied in detail and found that it satisfies all physical requirements needed for physically acceptable model.

gr-qc↗

arXiv2014

Modified Finch and Skea stellar model compatible with observational data

We present a new class of solutions to the Einstein's field equations corresponding to a static spherically symmetric anisotropic system by generalizing the ansatz of Finch and Skea [Class. Quantum Grav. 6 (1989) 467] for the gravitational potential $g_{rr}$. The anisotropic stellar model previously studied by Sharma and Ratanpal (2013) [Int. J. Mod. Phy. D 13 (2013) 1350074] is a sub-class of the solutions provided here. Based on physical requirements, regularity conditions and stability, we prescribe bounds on the model parameters. By systematically fixing values of the model parameters within the prescribed bound, we demonstrate that our model is compatible with the observed masses and radii of a wide variety of compact stars like 4U 1820-30, PSR J1903+327, 4U 1608-52, Vela X-1, PSR J1614-2230, SAX J1808.4-3658 and Her X-1.

physics.gen-ph↗