Cosmographic test of chameleon gravity

Salehi, Amin

doi:10.1007/s10714-023-03085-9

Cited by 2 publications

(1 citation statement)

References 163 publications

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“…This topic has been extensively discussed in various publications, including the original work of the chameleon model. All of the following consider the value of β in order of unity: Khoury & Weltman (2004a, 2004b Additionally, the α value obtained from this study is 0.51, which is in broad agreement with the findings presented in the aforementioned publications (Salehi & Farrajolahi 2012;0.54), and cosmography of chameleon gravity (Salehi 2023).…”

Section: Discussionsupporting

confidence: 91%

Can Chameleon Fields Be the Source of the Dark Energy Dipole and the Cosmic Microwave Background Dipole?

Yarahmadi,

Salehi

2024

ApJ

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Recent research reveals that the Local Group is in motion toward (l, b) = (276, 30) relative to the cosmic background radiation, manifesting a velocity of 600 km s−1, a phenomenon recognized as the cosmic background radiation dipole or cosmic microwave background dipole. Despite its well-documented nature, the precise cause of this peculiar motion remains elusive. High mass–density regions, such as galactic superclusters, stand out among the potential contributors to this cosmic flow. This paper employs chameleon fields to investigate anisotropies on both small and large scales. The data utilized in this study comprise Type Ia supernovae from the Pantheon catalog, totaling 1048 supernovae within the redshift range of 0.015 < z < 2.3. The analysis of the bulk flow at various redshifts has yielded noteworthy discoveries. On a smaller scale (less than 150 Mpc), the movement direction of the Local Group coincides with that of the bulk flow. On a larger scale, the bulk flow direction corresponds to the direction of the dark energy dipole. This implies that the anisotropy at the local scale originates from the same source as the anisotropy observed on a larger scale.

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Section: Discussionsupporting

confidence: 91%

Can Chameleon Fields Be the Source of the Dark Energy Dipole and the Cosmic Microwave Background Dipole?

Yarahmadi,

Salehi

2024

ApJ

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Cosmological solutions of chameleon scalar field model

Zaregonbadi,

Saba,

Farhoudi

2023

Eur. Phys. J. C

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We investigate cosmological solutions of the chameleon model with a non-minimal coupling between the matter and the scalar field through a conformal factor with gravitational strength. By considering the spatially flat FLRW metric and the matter density as a non-relativistic perfect fluid, we focus on the matter-dominated phase and the late-time accelerated-phase of the universe. In this regard, we manipulate and scrutinize the related field equations for the density parameters of the matter and the scalar fields with respect to the e-folding. Since the scalar field fluctuations depend on the background and the field equations become highly non-linear, we probe and derive the governing equations in the context of various cases of the relation between the kinetic and potential energies of the chameleon scalar field, or indeed, for some specific cases of the scalar field equation of state parameter. Thereupon, we schematically plot those density parameters for two different values of the chameleon non-minimal coupling parameter, and discuss the results. In the both considered phases, we specify that, when the kinetic energy of the chameleon scalar field is much less than its potential energy (i.e., when the scalar field equation of state parameter is $$\simeq - 1 $$ ≃ - 1 ), the behavior of the chameleon model is similar to the $$\Lambda CDM$$ Λ C D M model. Such compatibility suggests that the chameleon model is phenomenologically viable and can be tested with the observational data.

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Cosmographic test of chameleon gravity

Cited by 2 publications

References 163 publications

Can Chameleon Fields Be the Source of the Dark Energy Dipole and the Cosmic Microwave Background Dipole?

Can Chameleon Fields Be the Source of the Dark Energy Dipole and the Cosmic Microwave Background Dipole?

Cosmological solutions of chameleon scalar field model

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