Stability of the anisotropically inflating Bianchi type VI expanding solutions

2021

Eur. Phys. J. C

In this paper, we extend our investigation of the validity of the cosmic no-hair conjecture within non-canonical anisotropic inflation. As a result, we are able to figure out an exact Bianchi type I solution to a power-law k-inflation model in the presence of unusual coupling between scalar and electromagnetic fields as $$-f^2(\phi )F_{\mu \nu }F^{\mu \nu }/4$$ - f 2 ( ϕ ) F μ ν F μ ν / 4 . Furthermore, stability analysis based on the dynamical system method indicates that the obtained solution does admit stable and attractive hairs during an inflationary phase and therefore violates the cosmic no-hair conjecture. Finally, we show that the corresponding tensor-to-scalar ratio of this model turns out to be highly consistent with the observational data of the Planck 2018.

Section: Introductionmentioning

confidence: 99%

Stable small spatial hairs in a power-law k-inflation model

2021

Eur. Phys. J. C

“…The validity of the cosmic no-hair conjecture has also been tested in various cosmological models, including the higher curvature models [22][23][24][25][26][27][28], the Lorentz Chern-Simons theory [29,30], the massive vector theories [31][32][33][34], the nonlinear massive gravity models [35][36][37][38][39], the massive bigravity [40][41][42], and the supergravity-motivated models . Among these models, an interesting counter-example to the cosmic no-hair conjecture arising in the supergravitymotivated model proposed by Kanno, Soda, and Watanabe (KSW) [43,44] has attracted many attentions .…”

Section: Introductionmentioning

confidence: 99%

Anisotropic power-law inflation for a conformal-violating Maxwell model

Kao

2018

Eur. Phys. J. C

Self Cite

A set of power-law solutions of a conformalviolating Maxwell model with a non-standard scalar-vector coupling will be shown in this paper. In particular, we are interested in a coupling term of the form X 2n F μν F μν with X denoting the kinetic term of the scalar field. Stability analysis indicates that the new set of anisotropic power-law solutions is unstable during the inflationary phase. The result is consistent with the cosmic no-hair conjecture. We show, however, that a set of stable slowly expanding solutions does exist for a small range of parameters λ and n. Hence a small anisotropy can survive during the slowly expanding phase.

“…For the type-IX Bianchi spacetime, it will behave similarly if the cosmological constant Λ is sufficiently large [9]. Recently, there have been a number of discussions concerning the validity of the cosmic no-hair conjecture in various cosmological models including the higher curvature models [10,11], the Lorentz Chern-Simons theory [12], the massive vector theories [13], the supergravity-motivated models [14][15][16][17][18][19][20], the nonlinear massive gravity models [21], and the massive bigravity [22]. Moreover, the cosmic no-hair conjecture has also been extensively discussed in the case of inhomogeneous and anisotropic cosmology [23].…”

Section: Introductionmentioning

confidence: 99%

“…Among the models mentioned above [10][11][12][13][14][15][16][17][18][19][20][21][22], there is a famous counterexample to the cosmic no-hair conjecture derived from a supergravity-motivated model proposed by Kanno, Soda, and Watanabe (KSW) [14]. An interesting review on this model can be found in Ref.…”

Section: Introductionmentioning

confidence: 99%

Bianchi type I anisotropic power-law solutions for the Galileon models

Kao

2017

Phys. Rev. D

We will study the cosmological solutions of a class of Galileon models. A special class of the Bianchi type I power-law solutions will be presented in this paper. We will show that these Bianchi type I power-law solutions are stable during the inflationary phase. In addition, we will also show that the presence of a phantom field induces at least an unstable mode for the perturbation equation and destabilizes the powerlaw solutions.