Cosmology of f ( R ) gravity in the metric variational approach

By Baojiu Li, John D. Barrow. 2007

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We consider the cosmologies that arise in a subclass of f(R) gravity with f(R)=R+{mu}{sup 2n+2}/(-R){sup n} and n(set-membership sign)(-1,0) in the metric (as opposed to the Palatini) variational approach to deriving the gravitational field equations. The calculations of the isotropic and homogeneous cosmological models are undertaken in the Jordan frame and at both the background and the perturbation levels. For the former, we also discuss the connection to the Einstein frame in which the extra degree of freedom in the theory is associated with a scalar field sharing some of the properties of a 'chameleon' field. For the latter, we derive the cosmological perturbation equations in general theories of f(R) gravity in covariant form and implement them numerically to calculate the cosmic microwave background (CMB) temperature and matter power spectra of the cosmological model. The CMB power is shown to reduce at low l's, and the matter power spectrum is almost scale independent at small scales, thus having a similar shape to that in standard general relativity. These are in stark contrast with what was found in the Palatini f(R) gravity, where the CMB power is largely amplified at low l's and the matter spectrum is strongly scale dependent atmore » small scales. These features make the present model more adaptable than that arising from the Palatini f(R) field equations, and none of the data on background evolution, CMB power spectrum, or matter power spectrum currently rule it out.« less

Subfields: Astronomy and Astrophysics, Oceanography

View Paper: https://www.semanticscholar.org/paper/363c3431e29166da4607ef44fe086206524d64ff

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Citations in the corpus

f(R) Theories Of Gravity (2008, background): “…currently provide the most sensitive cosmological probe) and in galaxy surveys (Knox et al., 2006; Koivisto, 2006b; Koyama and Maartens, 2006; Li and Barrow, 2007; Li and Chu, 2006; Sealfon et al., 2005; Shirata et al., 2005, 2007; Skordis et al., 20 2006; Song et al., 2007; Stabenau and…”
Accurate halo-model matter power spectra with dark energy, massive neutrinos and modified gravitational forces (2016, background): “It was shown that f (R) models can exhibit the chameleon mechanism by Li & Barrow (2007), Hu & Sawicki (2007b) and Brax et al. (2008).”
ECOSMOG: an Efficient COde for Simulating MOdified Gravity (2011, background): “The leading example is the chameleon mechanism [5, 6, 14].”
Modified Gravity and Cosmology (2011, methodology): “This has been done for the case of a number of particular f(R) theories in [248, 310, 790, 5, 538] and also in the general case in [390, 306, 40, 253].”
f(R,T) Cosmological Models in Phase Space (2013, background): “Despite the results of local gravity tests, one can still look at these theories for cosmological solutions as an independent criterion [62].”