Accelerating Model of a Flat Universe in $$\boldsymbol{f(R,T)}$$ Gravity
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Accelerating Model of a Flat Universe in f (R, T ) Gravity Nishant Singla1* , Mukesh Kumar Gupta2** , and Anil Kumar Yadav3*** 1
Department of Physics, Suresh Gyan Vihar University, Jaipur, India School of Engineering and Technology, Suresh Gyan Vihar University, Jaipur, India 3 Department of Physics, United College of Engineering and Research, Greater Noida 201306, India 2
Received December 5, 2020; revised February 1, 2020; accepted February 7, 2020
Abstract—The f (R, T ) theory of gravity is an extended theory of gravity in which the gravitational action contains both the Ricci scalar R and the trace of the energy-momentum tensor T , and hence the cosmological models based on f (R, T ) gravity are eligible to describing the late-time acceleration of the present universe. In this paper, we investigate an accelerating model of a flat universe with a linearly varying deceleration parameter (LVDP). We apply the linear time-varying law for the deceleration parameter that generates a model of a transition from an early decelerating phase to the current accelerating phase. We carry out the state-finder and Om(z) analysis, and obtain that the LVDP model has a consistency with the astrophysical observations. We also profoundly discuss a violation of the energy-momentum conservation law in f (R, T ) gravity and the dynamic behavior of the model. DOI: 10.1134/S0202289320020103
1. INTRODUCTION The recent observational data [1] on the late-time acceleration of the universe and the existence of dark matter have posed a fundamental theoretical challenge to gravitational theories. However, the idea of modification of general relativity did not come to existence just after the discovery of the accelerating universe. Several modified theories of gravity, such as the Brans-Dike and other scalar-tensor theories, etc., exist for a long time due to a combined motivation coming from cosmology and astrophysics. After the discovery of the accelerating expansion of the universe, the attention of researchers towards modified gravity has increased, and the possibility that the modification of general relativity at cosmological scales can explain dark energy and dark matter becomes an active area of research since 2003 [2–6]. In [7–10], the authors have presented a model of the accelerating universe in Brans-Dicke theory of gravity. In particular, Goswami [7] has described the late-time acceleration of a homogeneous and isotropic universe due to the contribution of the cosmological constant in Brans-Dicke (BD) gravity, while Sharma et al., [9] have extended this work to Bianchi type I space-time. In Sen and Sen [8], the authors have obtained that while a perfect fluid (with or without pressure) cannot support the present *
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acceleration of the universe, a fluid with dissipative pressure can drive this acceleration for a simple power-law expansion of the universe. Akarsu et al. [10] have obtained some particular negative range of the BD coupling pa
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