AR_final file_2018-19

in the statefinder parameter - planes and ω − ω ′ plane, and it is observed that the parameter δ plays a magnificent role from the statefinder and ω − ω ′ plane viewpoints. Eventually, the evolution- ary trajectories are plotted considering two differ- ent values of THDE energy density (Ω 0 T ), Ω 0 T = 0 . 69, in the light of Planck 2018 results V I base- LCDM cosmology and Ω 0 T = 0 . 73, in the light of SNe + BAO + OHD + CMB observation data. This study has been done in collaboration with Umesh Kumar Sharma. Anisotropic compact stars in the Buchdahl models: A comprehensive study In this work, we present a class of relativistic so- lutions describing spherically symmetric and static anisotropic stars in hydrostatic equilibrium. For this purpose, we consider a particularized metric potential, namely, Buchdahl ansatz [Ph.Rv.D. 116 , 1027 (1959)], which encompasses almost all the known analytic solution to the spherically symmet- ric, static Einstein equations with a perfect fluid source, including in particular the Vaidya-Tikekar and Finch-Skea. We have developed the model by considering anisotropic spherically symmetric static general relativistic configuration that plays a significant effect on the structure and properties of stellar objects. We have considered eight differ- ent cases for generalized Buchdahl dimensionless parameter K , and analyzed them in an uniform manner. As a result, it turns out that all the con- sidered cases are valid at every point in the inte- rior spacetime. In addition to this, we show that the model satisfies all the energy conditions and maintain hydrostatic equilibrium equation. In the frame work of anisotropic hypothesis, we consider analogue objects with similar mass and radii such as LMC X-4, SMC X-1, EXO 1785-248, etc ., to restrict the model parameter arbitrariness. Also, establishing a relation between pressure and den- sity in the form of P = P ( ρ ), we demonstrate that EoSs can be approximated to a linear function of density. Despite the simplicity of this model, re- sults are satisfactory. This study has been done in collaboration with S. K. Maurya, Ayan Banerjee, M. K. Jasim, J. Kumar, and A. K. Prasad. Farook Rahaman Anisotropic strange stars under simplest minimal matter-geometry coupling in the f ( R, T ) gravity We study strange stars in the framework of f ( R, T ) theory of gravity. To provide exact solutions of the field equations it is considered that the gravi- tational Lagrangian can be expressed as the linear function of the Ricci scalar R and the trace of the stress-energy tensor T , i.e. f ( R, T ) = R + 2 χ T , where χ is a constant. We also consider that the strange quark matter (SQM) distribution in- side the stellar system is governed by the phe- nomenological MIT Bag model equation of state (EoS), given as p r = 1 3 ( ρ − 4 B ), where B is the Bag constant. Further, for a specific value of B and observed values of the strange star candi- dates we obtain the exact solution of the modi- fied Tolman-Oppenheimer-Volkoff (TOV) equation in the framework of f ( R, T ) gravity, and have stud- ied in detail the dependence of the different phys- ical parameters, like the metric potentials, energy density, radial and tangential pressures, anisotropy, etc., due to the chosen different values of χ , also we find maximum anisotropy at the surface which seems an inherent property of the strange stars in modified f ( R, T ) theory of gravity. To check the physical acceptability and stability of the stellar system based on the obtained solutions we have performed different physical tests, viz., the energy conditions, Herrera cracking concept, adiabatic in- dex, etc., we also have explained the effects, those are arising due to the interaction between the mat- ter and the curvature terms in f ( R, T ) gravity, on the anisotropic compact stellar system. The present study reveals that the modified f ( R, T ) gravity is a suitable theory to explain massive stel- lar systems like recent magnetars, massive pulsars and super-Chandrasekhar stars, which can not be explained in the framework of GR. However, for χ = 0 the standard results of Einsteinian gravity are retrieved. This study has been done in collabo- ration with Debabrata deb, B. K. Guha, and Saibal Ray. Solar system tests in constraining parameters of dyon black holes We examine the possibility of constraining dyon black holes based on the available observational data at the scale of the solar system. For this, we consider the classical tests of general relativity, ( 208 )