Parametrizations of dark energy models in the background of general non-canonical scalar field in D-dimensional fractal universe

Abstract

We have explored non-canonical scalar field model in the background of non-flat D-dimensional fractal Universe on the condition that the matter and scalar field are separately conserved. The potential V , scalar field φ, function f , densities, Hubble parameter and deceleration parameter can be expressed in terms of the redshift z and these depend on the equation of state parameter w φ . We have also investigated the cosmological analysis of four kinds of well known parametrization models. In graphically, we have analyzed the natures of potential, scalar field, function f , densities, the Hubble parameter and deceleration parameter. As a result, the best fitted values of the unknown parameters (w 0 , w 1 ) of the parametrization models due to the joint data analysis (SNIa+BAO+CMB+Hubble) have been found. Furthermore, the minimum values of χ 2 function have been obtained. Also we have plotted the graphs for different confidence levels 66%, 90% and 99% contours for (w 0 , w 1 ) by fixing the other parameters.

Multifractional theories: an unconventional review

“…In the theory T 1 with ordinary derivatives, the problem has been considered mainly with exotic dark-energy components, in flat 47,[57][58][59][60][61][62][63] as well as non-flat FLRW. 64,65 In these cases, late-time acceleration is possible, although the theoretical motivation is no more robust than in general relativity. However, it is indeed possible to realize dark energy with an ordinary fluid with mildly negative barotropic index w, 66 but it is not clear whether a scalar field with such properties would need fine tuning just like quintessence; hence the question mark in the table.…”

Dark energy in multifractional spacetimes

“…While there are some studies about inflation [18,19] and gravitational-wave propagation [20,21] that constrain or propose possible effects in the cosmic microwave background and in gravitational-wave signals in multifractional spacetimes, the problem of dark energy has received less attention, except in the case with ordinary derivatives. The absence of cosmological vacuum solutions in the theory with ordinary derivatives [16] led some to explore scenarios with more or less exotic dark-energy components [22][23][24][25][26][27][28][29] (see also [30,31] for a thermodynamical approach). However, our point of view is that a sensible theory beyond Einstein should be able to describe cosmic acceleration without introducing dark-energy fields by hand.…”

A model-independent method with phantom divide line crossing in Weyl-type f(Q,T) gravity

“…As SNe Ia measurements and other astronomical observations suggest that the cosmos is accelerating, a timedependent deceleration parameter is necessary to explain the transition from deceleration expansion in the past to accelerating expansion in the present. In line with this idea, different parametrizations have argued that deceleration parameter is time-dependent in order to examine various cosmological difficulties [42][43][44][45][46][47][48][49][50][51][52][53]. Motivated by the preceding debate, we use a generalization form of the deceleration parameter proposed in Eq.…”