Anisotropic universe with cosmic strings and bulk viscosity

Behera²,

Mishra

2015

Eur. Phys. J. C

Self Cite

Anisotropic dark energy cosmological models are constructed in the frame work of generalised BransDicke theory with a self-interacting potential. A unified dark fluid characterised by a linear equation of state is considered as the source of dark energy. The shear scalar is considered to be proportional to the expansion scalar simulating an anisotropic relationship among the directional expansion rates. The dynamics of the universe in the presence of a unified dark fluid in anisotropic background have been discussed. The presence of an evolving scalar field makes it possible to get an accelerating phase of expansion even for a linear relationship among the directional Hubble rates. It is found that the anisotropy in expansion rates does not affect the scalar field, the self-interacting potential, but it controls the non-evolving part of the Brans-Dicke parameter.

Section: Basic Equationssupporting

confidence: 77%

“…LRSBI models are more general than the usual FRW models and are based on exact solutions to the Einstein field equations with homogeneous but anisotropic flat spatial sections. LRSBI models have also been studied widely, in recent times, in different contexts [36][37][38][39][40][41].…”

Section: Introductionmentioning

confidence: 99%

Unified dark fluid in Brans–Dicke theory

Behera²,

Mishra

2015

Eur. Phys. J. C

Self Cite

“…The scalar expansion and shear scalar can be taken to be proportional to each other which provides us an anisotropic relation between the directional Hubble rates as H x = kH y [73]. Here, k takes care of the anisotropic nature of the model in the sense that, if k = 0, we get an isotropic universe, otherwise, the model is anisotropic.…”

Section: Dynamics Of An Anisotropic Universe In F (R) Gravitymentioning

confidence: 99%

Anisotropic solutions in f(R) gravity

Mishra

2016

Eur. Phys. J. Plus

Anisotropic cosmological models are investigated in the frame work of f (R) gravity in the metric formalism. Plane symmetric models are considered to incorporate anisotropy in the expansion rates along different spatial directions. The anisotropy in expansion rates are assumed to be maintained throughout the cosmic evolution. Two accelerating models are constructed by considering different functional forms for f (R). The viability of these models are tested through a stability analysis.

“…In order to address the issue of the smallness in the angular power spectrum of the temperature anisotropy, plane symmetric models have been proposed in recent times [38,39,40,41]. Plane Symmetric or Locally Rotationally Symmetric Bianchi type I (LRSBI) models have also been studied in different context to address different issues of cosmology [42,43,44,45,46,47,48,49,50]. These models are more interesting in the sense that they are more general then FRW models.…”

Section: Introductionmentioning

confidence: 99%

Cosmic acceleration and anisotropic models with magnetic field

Mahanta

2015

Eur. Phys. J. Plus

Plane symmetric cosmological models are investigated with or without any dark energy components in the field equations. Keeping an eye on the recent observational constraints concerning the accelerating phase of expansion of the universe, the role of magnetic field is assessed. In the absence of dark energy components, magnetic field can favour an accelerating model even if we take a linear relationship between the directional Hubble parameters. In presence of dark energy components in the form of a time varying cosmological constant, the influence of magnetic field is found to be limited.