Mild bounds on bigravity from primordial gravitational waves

Fasiello, Matteo; Ribeiro, Raquel H.

doi:10.1088/1475-7516/2015/07/027

Cited by 38 publications

(29 citation statements)

References 159 publications

(339 reference statements)

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“…[1,2] in 2012. In particular, studies of cosmological expansion histories [3][4][5][6][7][8], structure formation [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23], tensor modes [24][25][26][27], integrated Sachs-Wolfe effect [20] and galactic lensing [28] have been performed. The possibility to couple both fields that are present in the theory to matter has been explored in Refs.…”

Section: Introductionmentioning

confidence: 99%

On stars, galaxies and black holes in massive bigravity

Enander

Mörtsell

2015

J. Cosmol. Astropart. Phys.

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In this paper we study the phenomenology of stars and galaxies in massive bigravity. We give parameter conditions for the existence of viable star solutions when the radius of the star is much smaller than the Compton wavelength of the graviton. If these parameter conditions are not met, we constrain the ratio between the coupling constants of the two metrics, in order to give viable conditions for e.g. neutron stars. For galaxies, we put constraints on both the Compton wavelength of the graviton and the conformal factor and coupling constants of the two metrics. The relationship between black holes and stars, and whether the former can be formed from the latter, is discussed. We argue that the different asymptotic structure of stars and black holes makes it unlikely that black holes form from the gravitational collapse of stars in massive bigravity.

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Section: Introductionmentioning

confidence: 99%

On stars, galaxies and black holes in massive bigravity

Enander

Mörtsell

2015

J. Cosmol. Astropart. Phys.

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“…The problem of how cosmological observations are affected by these tensor instabilities and possible ways out are discussed in [50]. In [51] a general analysis of the tensor sector in models which are free from known instabilities is presented and it is discussed how measurements of the amplitude of primordial gravitational waves can be used to constrain them.…”

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confidence: 99%

Inflationary perturbations in bimetric gravity

Cusin¹,

Durrer²,

Guarato³

et al. 2015

J. Cosmol. Astropart. Phys.

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In this paper we study the generation of primordial perturbations in a cosmological setting of bigravity during inflation. We consider a model of bigravity which can reproduce the ΛCDM background and large scale structure and a simple model of inflation with a single scalar field and a quadratic potential. Reheating is implemented with a toy-model in which the energy density of the inflaton is entirely dissipated into radiation. We present analytic and numerical results for the evolution of primordial perturbations in this cosmological setting. We find that the amplitude of tensor perturbations generated during inflation is sufficiently suppressed to avoid the effects of the tensor instability discovered in Refs. [1,2] which develops during the cosmological evolution in the physical sector. We argue that from a pure analysis of the tensor perturbations this bigravity model is compatible with present observations. However, we derive rather stringent limits on inflation from the vector and scalar sectors.

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“…The total tensor power spectrum ultimately depends on the power transmitted to the CMB photons. Therefore, the coupling of the tensor fields to matter dictates how their power spectra are combined [16]. The matter action reads [11]…”

Section: Inflationary Observablesmentioning

confidence: 99%