$f(T)$ gravity after GW170817 and GRB170817A

Cai, Yi-Fu; Li, Chunlong; Saridakis, Emmanuel N.; Xue, LingQin

doi:10.48550/arxiv.1801.05827

Cited by 28 publications

(38 citation statements)

References 49 publications

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“…Thus, for f (T ) gravity at first order, the effect of the cosmological constant on the gravitational waves is also affected by the value of f T (0), as was also found in [52]. Lastly, in the case of TEGR these equations match identically to those of GR, as expected.…”

Section: B Tetrad Solutions For Gws In F (T B) Gravitysupporting

confidence: 74%

“…Note that this concerns the effect on the "internal" properties of the gravitational waves, as for instance in their polarization modes, where it was known that no further polarization modes are present in f (T ) gravity at first-order perturbation levels [50,51]. However, we stress that in general the effect of f (T ) gravity on the cosmological gravitational wave propagation can be seen straightaway from the dispersion relation at first order, due to the effect of f (T ) gravity on the cosmological background itself [52].…”

Section: Higher Order Metric Perturbationsmentioning

confidence: 70%

“…Note that obtaining the perturbed tetrad is not a trivial task in general, since amongst the infinite choices of perturbed tetrad ansatzes corresponding to the same perturbed metric, one should use the appropriate ones in order to obtain consistency [25,52,59].…”

Section: A Tetrad Solutions For Gws In F (T ) Gravitymentioning

confidence: 99%

“…These observations are very important for alternative theories of gravity, since in general one can obtain extra polarization modes or variant speed. Although there have been some works investigating gravitational waves in f (T ) gravity [50][51][52], the systematic study of gravitational waves in modified teleparallel gravities has not been performed.…”

Section: Introductionmentioning

confidence: 99%

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Gravitational waves in modified teleparallel theories

et al. 2018

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We investigate the gravitational waves and their properties in various modified teleparallel theories, such as f (T ), f (T, B) and f (T, TG) gravities. We perform the perturbation analysis both around a Minkowski background, as well as in the case where a cosmological constant is present, and for clarity we use both the metric and tetrad language. For f (T ) gravity we verify the result that no further polarization modes comparing to general relativity are present at first-order perturbation level, and we show that in order to see extra modes one should look at third-order perturbations.For non-trivial f (T, B) gravity, by examining the geodesic deviation equations, we show that extra polarization models, namely the longitudinal and breathing modes, do appear at first-order perturbation level, and the reason for this behavior is the fact that although the first-order perturbation does not have any effect on T , it does affect the boundary term B. Finally, for f (T, TG) gravity we show that at first-order perturbations the gravitational waves exhibit the same behavior to those of f (T ) gravity. Since different modified teleparallel theories exhibit different gravitational wave properties, the advancing gravitational-wave astronomy would help to alleviate the degeneracy not only between curvature and torsional modified gravity but also between different subclasses of modified teleparallel gravities.

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Section: B Tetrad Solutions For Gws In F (T B) Gravitysupporting

confidence: 74%

Section: Higher Order Metric Perturbationsmentioning

confidence: 70%

Section: A Tetrad Solutions For Gws In F (T ) Gravitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Gravitational waves in modified teleparallel theories

et al. 2018

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“…For the completeness we point out that the recent detection of gravity waves by LIGO observatory puts a constraint on the speed of gravity wave and in turn this constraint can further restrict the parameter space of higher derivative theories ref. [41][42][43][44][45][46][47][48][49][50][51][52][53][54][55]. This fact motivates us to include additional higher derivative terms in these theories, which may obtain a larger allowed parameter space from the speed of gravity wave.…”

Section: Introductionmentioning

confidence: 99%

Higher Derivative Scalar Tensor Theory in Unitary Gauge

Joshi,

Panda

2021

Preprint

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Ostrogradsky instability generally appears in nondegenerate higher-order derivative theories and this issue can be resolved by removing any existing degeneracy present in such theories. We consider an action involving terms that are at most quadratic in second derivatives of the scalar field and nonminimally coupled with the curvature tensors. We perform a 3+1 decomposition of the Lagrangian to separate second-order time derivative terms from rest. This decomposition is useful for checking the degeneracy hidden in the Lagrangian and helps us find conditions under which Ostrogradsky instability does not appear. We show that our construction of Lagrangian resembles that of a GRlike theory for a particular case in the unitary gauge. As an example, we calculate the equation of motion for the flat FRW. We also write the action for open and closed cases, free from higher derivatives for a particular choice derived from imposing degeneracy conditions.

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Constraining teleparallel gravity through Gaussian processes

Briffa

Capozziello

Said

et al. 2020

Class. Quantum Grav.

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We apply Gaussian processes (GP) in order to impose constraints on teleparallel gravity and its f(T) extensions. We use available H(z) observations from (i) cosmic chronometers data (CC); (ii) Supernova type Ia (SN) data from the compressed pantheon release together with the CANDELS and CLASH multi-cycle treasury programs; and (iii) baryonic acoustic oscillation (BAO) datasets from the sloan digital sky survey. For the involved covariance functions, we consider four widely used choices, namely the square exponential, Cauchy, Matérn and rational quadratic kernels, which are consistent with one another within 1σ confidence levels. Specifically, we use the GP approach to reconstruct a model-independent determination of the Hubble constant H 0, for each of these kernels and dataset combinations. These analyses are complemented with three recently announced literature values of H 0, namely (i) Riess H 0 R = 74.22 ± 1.82 k m s − 1 M p c − 1 ; (ii) H0LiCOW collaboration H 0 HW = 73 . 3 − 1.8 + 1.7 k m s − 1 M p c − 1 ; and (iii) Carnegie–Chicago Hubble programme H 0 TRGB = 69.8 ± 1.9 k m s − 1 M p c − 1 . Additionally, we investigate the transition redshift between the decelerating and accelerating cosmological phases through the GP reconstructed deceleration parameter. Furthermore, we reconstruct the model-independent evolution of the dark energy equation of state, and finally reconstruct the allowed f(T) functions. As a result, the ΛCDM model lies inside the allowed region at 1σ in all the examined kernels and datasets, however a negative slope for f(T) versus T is slightly favoured.

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$f(T)$ gravity after GW170817 and GRB170817A

Cited by 28 publications

References 49 publications

Gravitational waves in modified teleparallel theories

Gravitational waves in modified teleparallel theories

Higher Derivative Scalar Tensor Theory in Unitary Gauge

Constraining teleparallel gravity through Gaussian processes

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