The hidden flat like universe II

Hanafy, W. El; Nashed, G. G. L.

doi:10.1007/s10509-016-2853-6

Cited by 25 publications

(25 citation statements)

References 66 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[7-14, 16-20, 38], while inflationary and bouncing scenarios in relation with cosmological perturbation scenarios were studied in Refs. [21][22][23][24][25][26][27]. Moreover, special cosmological solutions where found in Refs.…”

Section: Introductionmentioning

confidence: 90%

Viability of the intermediate inflation scenario with F(T) gravity

Oikonomou

2017

Phys. Rev. D

View full text Add to dashboard Cite

We study the intermediate inflation scenario in the context of F (T ) gravity, and we examine it's viability by calculating the power spectrum of the primordial curvature perturbations and the corresponding spectral index. As we demonstrate, it is possible for the resulting spectral index to be compatible with the observational data and we investigate the parameter space in order to see when the compatibility with data is possible.

show abstract

Section: Introductionmentioning

confidence: 90%

Viability of the intermediate inflation scenario with F(T) gravity

Oikonomou

2017

Phys. Rev. D

View full text Add to dashboard Cite

show abstract

“…This constraint facilitates the calculations and makes the above differential equations solvable. (v) Equation (27) shows that the Cauchy horizon of g tt = 0 and the horizons constructed from g rr = 0 are the same, which is familiar in GR (TEGR). However, this condition is not satisfied for Eq.…”

Section: Singularitiesmentioning

confidence: 96%

“…However, this condition is not satisfied for Eq. (27). We may say that this is due to the contribution of the higher order torsion.…”

Section: Singularitiesmentioning

confidence: 99%

“…This process was suggested by Einstein who called it a "teleparallel equivalent of general relativity" (TEGR) [1,[25][26][27][28][29][30]. This theory, TEGR, is closely related to GR and differs only by a total derivative term in the action.…”

Section: Introductionmentioning

confidence: 99%

“…It is necessary to note that in f (T ) theory the field equations are of second order while the field equations of f (R) are of fourth order. Different aspects of cosmology in f (T ) theory have been discussed in the literature [49][50][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65][66][67].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Analytic rotating black-hole solutions in N-dimensional f(T) gravity

Nashed

Hanafy

2017

Eur. Phys. J. C

Self Cite

View full text Add to dashboard Cite

A non-diagonal vielbein ansatz is applied to the N -dimension field equations of f (T ) gravity. An analytical vacuum solution is derived for the quadratic polynomial f (T ) = T + T 2 and an inverse relation between the coupling constant and the cosmological constant . Since the induced metric has off-diagonal components, it cannot be removed by a mere coordinate transformation, the solution has a rotating parameter. The curvature and torsion scalars invariants are calculated to study the singularities and horizons of the solution. In contrast to general relativity, the Cauchy horizon differs from the horizon which shows the effect of the higher order torsion. The general expression of the energy-momentum vector of f (T ) gravity is used to calculate the energy of the system. Finally, we have shown that this kind of solution satisfies the first law of thermodynamics in the framework of f (T ) gravitational theories.

show abstract

f(T) teleparallel gravity and cosmology

et al. 2016

View full text Add to dashboard Cite

Over the past decades, the role of torsion in gravity has been extensively investigated along the main direction of bringing gravity closer to its gauge formulation and incorporating spin in a geometric description. Here we review various torsional constructions, from teleparallel, to Einstein-Cartan, and metric-affine gauge theories, resulting in extending torsional gravity in the paradigm of f (T ) gravity, where f (T ) is an arbitrary function of the torsion scalar. Based on this theory, we further review the corresponding cosmological and astrophysical applications. In particular, we study cosmological solutions arising from f (T ) gravity, both at the background and perturbation levels, in different eras along the cosmic expansion. The f (T ) gravity construction can provide a theoretical interpretation of the late-time universe acceleration, alternative to a cosmological constant, and it can easily accommodate with the regular thermal expanding history including the radiation and cold dark matter dominated phases. Furthermore, if one traces back to very early times, for a certain class of f (T ) models, a sufficiently long period of inflation can be achieved and hence can be investigated by cosmic microwave background observations, or alternatively, the Big Bang singularity can be avoided at even earlier moments due to the appearance of non-singular bounces. Various observational constraints, especially the bounds coming from the large-scale structure data in the case of f (T ) cosmology, as well as the behavior of gravitational waves, are described in detail. Moreover, the spherically symmetric and black hole solutions of the theory are reviewed. Additionally, we discuss various extensions of the f (T ) paradigm. Finally, we consider the relation with other modified gravitational theories, such as those based on curvature, like f (R) gravity, trying to enlighten the subject of which formulation, or combination of formulations, might be more suitable for quantization ventures and cosmological applications. Contents

show abstract

The hidden flat like universe II

Cited by 25 publications

References 66 publications

Viability of the intermediate inflation scenario with F(T) gravity

Viability of the intermediate inflation scenario with F(T) gravity

Analytic rotating black-hole solutions in N-dimensional f(T) gravity

f(T) teleparallel gravity and cosmology

Contact Info

Product

Resources

About