Existence of compact structures in f(R, T) gravity

The European Physical Journal C, Apr 2018

The present paper is devoted to investigate the possible emergence of relativistic compact stellar objects through modified f(R, T) gravity. For anisotropic matter distribution, we used Krori and Barura solutions and two notable and viable f(R, T) gravity formulations. By choosing particular observational data, we determine the values of constant in solutions for three relativistic compact star candidates. We have presented some physical behavior of these relativistic compact stellar objects and some aspects like energy density, radial as well as transverse pressure, their evolution, stability, Eos parameters, measure of anisotropy and energy conditions.

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Existence of compact structures in f(R, T) gravity

Eur. Phys. J. C Existence of compact structures in f ( R, T ) gravity Z. Yousaf 1 M. Zaeem-ul-Haq Bhatti 0 1 M. Ilyas 0 0 Centre for High Energy Physics, University of the Punjab , Quaid-i-Azam Campus, Lahore 54590 , Pakistan 1 Department of Mathematics, University of the Punjab , Quaid-i-Azam Campus, Lahore 54590 , Pakistan The present paper is devoted to investigate the possible emergence of relativistic compact stellar objects through modified f ( R, T ) gravity. For anisotropic matter distribution, we used Krori and Barura solutions and two notable and viable f ( R, T ) gravity formulations. By choosing particular observational data, we determine the values of constant in solutions for three relativistic compact star candidates. We have presented some physical behavior of these relativistic compact stellar objects and some aspects like energy density, radial as well as transverse pressure, their evolution, stability, Eos parameters, measure of anisotropy and energy conditions. 1 Introduction General relativity (GR) is considered as the most fruitful theory for understanding the evolution of universe and its hidden secrets, yet the evidence of dark matter (DM) and the cosmic accelerating nature of spacetime put some challenges on this [ 1–15 ]. The Einstein’s GR explained the cosmological phenomena in a regime of weak field, while some modifications may be needed to study the strong fields in the scenario of accelerating expansion of the universe. In this direction, Qadir et al. [ 16 ] reinforced the requirement of the modified relativistic dynamics and indicated that this modification may help to settle down the problems related to DM and quantum gravity. As a result, many techniques were used like by introducing the cosmological constant as well as the modified theories from time to time. Modified gravitational theories (MGTs) are actually the generalization of GR in which function of the Ricci scalar ( R) is substituted in the Einstein–Hilbert action. These modified gravity theories are dubbed with the names, Einstein[ 17 ], f ( R) [ 18–21 ] ( R is the Ricci scalar), f ( R, T ) [ 22–25 ] (T is the trace of energy momentum tensor), f (G) [ 26 ] (G is the Gauss–Bonnet term) and f ( R, T , Rξ π T ξ π ) gravity [ 27– 30 ]. In the recent times, Nojiri et al. [31] presented various mathematical techniques to understand burning issues of cosmos related to bouncing cosmos. They asserted that gravity mediated by f ( R) and f (G) theories could be used to realize many hidden secrets of our universe. Once can observe the pity good agreement results between the cosmological models in MGTs and the observational data [ 32–35 ]. The f ( R, T ) gravity is one of the MGTs, in which the f ( R) is replaced with the function of R and T [36]. It is claimed that the evidence behind the dependence of T may come from the presence of imperfect fluid or it may be some kinds of quantum effects (for further reviews on DE and MGTs, see, for instance, [ 37–51 ]). In f ( R, T ) gravity, many cosmological applications were discussed in [ 52–58 ]. From literature, some of them are, The non-static line element for collapsing of spherical body having anisotropic fluid were discussed in [ 59 ]. The static spherical wormhole solutions were found in [ 60, 61 ]. Furthermore, the perturbation techniques were used in study of spherical stars [62]. The effects on gravitational lensing due to f ( R, T ) gravity were discussed in [ 63 ]. The spherical equilibrium theme of polytropic and strange stars were investigated in [ 64 ]. Houndjo [ 65 ] constructed few observationally notable cosmic models in f ( R, T ) gravity for studying matter dominated era of the expanding universe. Baffou et al. [ 66 ] applied perturbation on the spacetimes of de-Sitter and power law models in order to explore some cosmic viability bounds. Bamba et al. [ 67 ] analyzed the effects of higher degrees of freedom coming from MGT on the dynamical features of our accelerating cosmos. Bamba et al. [ 73 ] further checked the viability regimes on the parameters of f (G) gravity models and presented some mathematically consistent cosmic zones. The stability of gravitational evolving stellar bodies have been investigated in few models of f (R) gravity by [ 69,71 ]. Das et al. [72] calculated exact relativistic models of spherical interiors in MGT and discussed the physical implications of their results on compact stars. Yousaf and his collaborators examined the role of various curvature invariant functions on the existence as well as stability of the planar [ 74–76 ], spherical [ 17,77–80 ] and cylindrical [ 23,81–83 ] geometries. Sahoo with his coworkers [ 84–86 ] studied the viability of the spatially regular cosmos along with some other cosmological aspects in f (R, T ) gravity. Moraes et al. [64] worked out the stability of some well-known compact stars by computing their corresponding hydrostatic equations in f (R, T (...truncated)


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Z. Yousaf, M. Zaeem-ul-Haq Bhatti, M. Ilyas. Existence of compact structures in f(R, T) gravity, The European Physical Journal C, 2018, pp. 307, Volume 78, Issue 4, DOI: 10.1140/epjc/s10052-018-5797-x