Cosmological consequences in the framework of generalized Rastall theory of gravity

Abstract

The paper deals with generalized Rastall theory of gravity and its cosmological consequences in the background of homogeneous and isotropic flat FLRW model with perfect fluid as the matter context. The model shows a non singular era (emergent scenario) at the early phase of expansion for a particular choice of the Rastall parameter. Also the model finds to be equivalent to the particle creation mechanism in Einstein gravity in the framework of non-equilibrium thermodynamics. Universal thermodynamics is briefly presented and it is found that the entropy function in Rastall theory is the usual Bekenstein entropy and there is no correction to it. Finally, a complete cosmic history starting from inflation to late time acceleration is presented for suitable choices of the Rastall parameter.

Non-minimal coupling inspires the Dirac cosmological model

“…In this case d 0 is a free parameter, and some outcomes of this proposal in various cosmic eras have also been studied in Ref. [62]. Accepting this proposal along with considering the unit κ = 8πG 0 and also assuming G(H 0 ) = G 0 (which helps us in finding d 0 ), one easily reaches…”

“…In Ref. [62], choosing λ = (1 + d 0 H)/[3κ(w + 1)], in which w ≡ p/ρ (where p and ρ denote the pressure and energy density of the cosmic fluid, respectively), it has been shown that non-singular cosmic evolution is obtainable in GRT. In this case d 0 is a free parameter, and some outcomes of this proposal in various cosmic eras have also been studied in Ref.…”

“…The study of various non-minimal couplings can at least make us familiar with their consequences and properties which may finally lead to a better understanding of spacetime that helps us provide better predictions about its behavior and nature. In GRT, cosmological scenarios [43,59,62,63] imply the power of non-minimal coupling in i) providing both singular and non-singular universes, ii) describing the particle production process, iii) avoiding the coincidence problem, and iv) playing the role of dark energy (unlike the original Rastall theory [43,64]). In this regard, thermodynamically it has also been shown that the confusion in defining energy and some of its outcomes which may lead to the OCL generalization (or equivalently, the breakdown of OCL) could make the cosmos dark [65,66].…”

Qualitative aspects of Rastall gravity with barotropic fluid

“…Rastall's gravity has extensively been studied in different cosmological contexts. [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]. A qualitative study of Rastall gravity by using phase plane analysis may give insight on class of solutions available in this theory.…”

“…The exploration of thermodynamic properties at apparent horizon in Rastall gravity with entropy correction have been done by Bamba et al [19]. Das et al [20] have discussed cosmological consequences and universal thermodynamics in Rastall gravity by illustrating a complete cosmological history starting from inflation to late-time acceleration. Cruz et al [23] have presented a thermodynamic discussion of Rastall gravity by introducing chemical potential.…”