Dark matter in ghost-free bigravity theory: From a galaxy scale to the universe

Aoki, Katsuki; Maeda, Kei Ichi

doi:10.1103/physrevd.90.124089

Cited by 34 publications

(42 citation statements)

References 74 publications

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“…where {b k } (k = 0 -4) are coupling constants and the 4×4 matrix 4) while U k are the elementary symmetric polynomials of the eigenvalues of the matrix γ, defined explicitly in [11,12]. Taking the variation of the action with respect to g µν and f µν , we find two sets of the Einstein equations:…”

Section: Hassan-rosen Bigravity Modelmentioning

confidence: 99%

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Relativistic stars in bigravity theory

2016

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Assuming static and spherically symmetric spacetimes in the ghost-free bigravity theory, we find a relativistic star solution, which is very close to that in general relativity. The coupling constants are classified into two classes: Class [I] and Class [II]. Although the Vainshtein screening mechanism is found in the weak gravitational field for both classes, we find that there is no regular solution beyond the critical value of the compactness in Class [I]. This implies that the maximum mass of a neutron star in Class [I] becomes much smaller than that in GR. On the other hand, for the solution in Class [II], the Vainshtein screening mechanism works well even in a relativistic star and the result in GR is recovered.

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Section: Hassan-rosen Bigravity Modelmentioning

confidence: 99%

“…[γ]µ ν and T [γ]µ ν are obtained by the variation of the interaction term with respect to g µν and f µν , respectively, taking the form [11,12] …”

Section: Hassan-rosen Bigravity Modelmentioning

confidence: 99%

Relativistic stars in bigravity theory

2016

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“…[γ]µ ν are obtained by the variation of the dRGT potential action with respect to g µν and f µν , respectively, taking the form [25,30] …”

Section: )mentioning

confidence: 99%

“…Therefore, the present acceleration of the Universe can be explained by adding a mass to the graviton (see also [11-13, 15, 26-29] about the cosmology in the dRGT theory). Furthermore, since the bigravity theory contains two metrics, a matter field in the fiducial metric sector is naturally introduced, and it may act as a dark matter component in the physical sector [25,30].…”

Section: Introductionmentioning

confidence: 99%

Stability of the early universe in bigravity theory

2015

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We study the stability of a spherically symmetric perturbation around the flat FriedmannLemaître-Robertson-Walker spacetime in the ghost-free bigravity theory, retaining nonlinearities of the helicity-0 mode of the massive graviton. It has been known that, when the graviton mass is smaller than the Hubble parameter, homogeneous and isotropic spacetimes suffer from the Higuchitype ghost or the gradient instability against the linear perturbation in the bigravity. Hence, the bigravity theory has no healthy massless limit for cosmological solutions at linear level. In this paper we show that the instabilities can be resolved by taking into account nonlinear effects of the scalar graviton mode for an appropriate parameter space of coupling constants. The growth history in the bigravity can be restored to the result in general relativity in the early stage of the Universe, in which the Stückelberg fields are nonlinear and there is neither ghost nor gradient instability. Therefore, the bigravity theory has the healthy massless limit, and cosmology based on it is viable even when the graviton mass is smaller than the Hubble parameter.

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“…The cosmological constant could be effectively produced from the interactions between two metric tensors [32][33][34][35][36], and the massive spin-2 fields and matter fields coupled to the metric f µν can be candidates for dark matter [37][38][39][40]. If we regard the bigravity as an alternative theory of gravity, it is interesting and significant that we apply this theory to other phenomena in cosmology or astrophysics and find the differences from general relativity.…”

Section: Introductionmentioning

confidence: 99%

Anti-Evaporation of Black Holes in Bigravity

Katsuragawa

2015

Universe

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We review properties of solutions in bigravity theory for a specific case where two metric tensors, g µν and f µν , satisfy proportional relation f µν = C 2 g µν . For this condition, we find that the solutions describing the asymptotically de Sitter space-time can be obtained and investigate the perturbation around the Schwarzschild-de Sitter solutions and corresponding anti-evaporation. We discuss the stability under special perturbations related to the anti-evaporation and the importance of the non-diagonal components of the metric in bigravity.

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Dark matter in ghost-free bigravity theory: From a galaxy scale to the universe

Cited by 34 publications

References 74 publications

Relativistic stars in bigravity theory

Relativistic stars in bigravity theory

Stability of the early universe in bigravity theory

Anti-Evaporation of Black Holes in Bigravity

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