A new class of LRS Bianchi type-II dark energy models with variable EoS parameter

Abstract

A new class of dark energy models in a Locally Rotationally Symmetric Bianchi type-II (LRS B-II) spacetime with variable equation of state (EoS) parameter and constant deceleration parameter have been investigated in the present paper. The Einstein's field equations have been solved by applying a variation law for generalized Hubble's parameter given by Berman: Nuovo Cimento 74:182 (1983) which generates two types of solutions for the average scale factor, one is of power-law type and other is of the exponential-law form. Using these two forms, Einstein's field equations are solved separately that correspond to expanding singular and non-singular models of the universe respectively. The dark energy EoS parameter ω is found to be time dependent and its existing range for both models is in good agreement with the three recent observations of (i) SNe Ia data (Knop et al.: Astrophys. J. 598:102 (2003)), (ii) SNe Ia data collaborated with CMBR anisotropy and galaxy clustering statistics (Tegmark et al.: Astrophys. J. 606:702 (2004)) and latest (iii) a combination of cosmological datasets coming from CMB anisotropies, luminosity dis-A. Pradhan ( ) · R. Jaiswal tances of high redshift type Ia supernovae and galaxy clustering (Hinshaw et al.: Astrophys. J. Suppl. 180:225 (2009); Komatsu et al. Astrophys. J. Suppl. 180:330 (2009)). The cosmological constant is found to be a positive decreasing function of time and it approaches a small positive value at late time (i.e. the present epoch) which is corroborated by results from recent supernovae Ia observations. The physical and geometric behaviour of the universe have also been discussed in detail.

Anisotropic modified holographic Ricci dark energy cosmological model with hybrid expansion law

“…The directional Hubble parameters, expressing the volumetric expansion rates of the universe along the x, y and z directions respectively are (Pradhan et al 2011)…”

Accelerating dark energy models of the universe in anisotropic Bianchi type space-times and recent observations

“…We also observe that if (81) for t = t 0 , ω = -1 (i.e. cosmological constant domi nated universe), and when t < t 0 , ω > -1 (i.e.…”

“…Setare [64][65][66] and Setare and Saridakis [67][68][69] have also studied the DE models in different contexts. Recently, dark energy models with variable EoS parameter have been studied by Ray et al [70], Akarsu and Kilinc [71][72][73][74], Yadav et al [75], Yadav and Yadav [76], Yadav and Saha [77] Pradhan and Amirhashchi [78,79], Pradhan et al [80][81][82], Amirhashchi et al [83][84][85][86], Kumar [87,88], Kumar and Akarsu [89], Kumar and Yadav [90] and Kumar and Singh [91]. In well known reviews on modified gravity [92,93], it is clearly indicated that any modified gravity may be represented as effective fluid with time dependent ω.…”

The Measurement of and in Bianchi Type-I Anisotropic Dark Energy Cosmological Model with Constant Deceleration Parameter in Bimetric Theory of Gravitation

“…For closed universe, the Hubble parameter , H the matter energy density parameter M  and the dark energy density parameter ,   predicted by Tegmark [12] by Sahni et al [23][24].This parameter ) ( t  have been calculated with some reasoning with reduced to some simple parameterization of the dependences by many authors [25][26][27][28][29][30]. The results from SNe Ia data collaborated with CMBR anisotropy and galaxy clustering statistics (Tegmark et al [12] [39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54].…”