Matter density perturbations in modified teleparallel theories

Wu, Yi-Peng; Geng, Chao–Qiang

doi:10.1007/jhep11(2012)142

Cited by 54 publications

(48 citation statements)

References 51 publications

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“…In this subsection, we review in detail the linear-order dynamics of perturbations of f (T ) gravity within the cosmological frame, following [196] (see also [278]). For simplicity, we investigate scalar perturbations in the Newtonian gauge and provide the full set of gravitational and energy-momentum tensor up to linear order.…”

Section: E Perturbations In F (T ) Gravitymentioning

confidence: 99%

f(T) teleparallel gravity and cosmology

et al. 2016

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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

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Section: E Perturbations In F (T ) Gravitymentioning

confidence: 99%

f(T) teleparallel gravity and cosmology

et al. 2016

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“…The rotation we perform is specified by three Euler angles such that first we turn around the Ψ-axis by the angle − arcsin(cos Ψ), then around the Θ-axis by the angle π/2 − Θ, and finally around the Φ-axis by the angle Φ. The tetrad we then obtain seems like a "good" one (from the result (34) we'll shortly arrive at) though a lot messier (we omit writing down the 16 nonzero components explicitly). At this point, it is more convenient to rescale the hyper-angular coordinates y i → √ Ky i , so that they have the conventional dimension of length.…”

Section: On Generalisations To Curved Frw and Rotated Tetradsmentioning

confidence: 99%

Cosmological perturbations in modified teleparallel gravity models

Golovnev

Koivisto

2018

J. Cosmol. Astropart. Phys.

153

183

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Cosmological perturbations are considered in f (T ) and in scalar-torsion f (ϕ)T teleparallel models of gravity. Full sets of linear perturbation equations are accurately derived and analysed at the relevant limits. Interesting features of generalisations to other teleparallel models, spatially curved backgrounds, and rotated tetrads are pointed out.1 One may remind that rather than something "extra" or "alternative", the tetrad is necessary to couple matter to gravitation. Only currently, a new preprint claims to consistently supersede the tetrad by a more minimal structure, which may shed new light on the singularity resolution and, surprisingly, the nature of dark matter [4].2 Unfortunately, with a typo (missing prime for the extra perturbation in the space-space field equation) inherited in [22].

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“…where α and B a i are extra degrees of freedom and ∂ i ∂ j B ij = 0 [32][33][34]. Extra degrees of freedom do not appear in metric.…”

Section: The Problem Of Energy In the Frw Spacetimementioning

confidence: 99%

Cosmological perturbations in gravitational energy–momentum complex

2019

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Starting from the energy-momentum of matter and gravitational field in the framework of General Relativity and Teleparallel Gravity, we obtain the energy-momentum complex in flat FRW spacetime. We show that the complex vanishes at background level considering the various prescriptions, that is the Einstein, Møller, Landau-Lifshitz and Bergmann ones. On the other hand, at level of linear cosmological perturbations, the energy-momentum complex is different from zero and coincides in the various prescriptions. Finally, we evaluate the gravitational energy for different cosmological epochs governed by non-relativistic matter, radiation, inflationary scalar fields and cosmological constant.

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Matter density perturbations in modified teleparallel theories

Cited by 54 publications

References 51 publications

f(T) teleparallel gravity and cosmology

f(T) teleparallel gravity and cosmology

Cosmological perturbations in modified teleparallel gravity models

Cosmological perturbations in gravitational energy–momentum complex

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