Curvature Quintessence Matched With Observational Data

Capozziello, Salvatore; Cardone, V. F.; Carloni, Sante; Troisi, A.

doi:10.1142/s0218271803004407

Cited by 612 publications

(547 citation statements)

References 21 publications

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“…It is also clear that power-law solutions do exist in general for f (R) models, but they can be found using different methods [24]. Assuming, in general, a power-law H(a), one finds R as a function of a, and then, in principle, f = f (R(a)).…”

Section: Non-noether Solutionsmentioning

confidence: 99%

f(R) cosmology from Noether’s symmetry

Capozziello

Felice

2008

J. Cosmol. Astropart. Phys.

198

218

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A general approach to find out exact cosmological solutions in f (R)-gravity is discussed. Instead of taking into account phenomenological models, we assume, as a physical criterium, the existence of Noether symmetries in the cosmological f (R) Lagrangian. As a result, the presence of such symmetries selects viable models and allow to solve the equations of motion. We discuss also the case in which no Noether charge is present but general criteria can be used to achieve solutions.PACS numbers: 04.50.+h, 95.36.+x, 98.80.-k

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Section: Non-noether Solutionsmentioning

confidence: 99%

f(R) cosmology from Noether’s symmetry

Capozziello

Felice

2008

J. Cosmol. Astropart. Phys.

198

218

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“…A possible way out is to evaluate PPN parameters for the case of f (R) gravity exploiting the analogy between fourth order theories and scalar -tensor ones. Such an analysis has been indeed performed by some of us [35] and will be presented in a forthcoming work.…”

Section: Discussionmentioning

confidence: 91%

Dark energy exponential potential models as curvature quintessence

Capozziello

Cardone

Piedipalumbo

et al. 2006

Class. Quantum Grav.

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It has been recently shown that, under some general conditions, it is always possible to find a fourth order gravity theory capable of reproducing the same dynamics of a given dark energy model. Here, we discuss this approach for a dark energy model with a scalar field evolving under the action of an exponential potential. In absence of matter, such a potential can be recovered from a fourth order theory via a conformal transformation. Including the matter term, the function f (R) entering the generalized gravity Lagrangian can be reconstructed according to the dark energy model. 04.50+h, 98.80.Jk, 98.80.Es

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“…(20) and the constraints in Eqs. (29) and (30). For the best fit model, it is t 0 = 10.3 Gyr, while t 0 ranges between 10 and 11 Gyr for the parameters running in their 1σ confidence regions.…”

Section: A F (R) = βR Nmentioning

confidence: 98%

“…In particular, in Ref. [30], some of us have also successfully tested a simplified version of this model (with no matter term) against the SNeIa Hubble diagram. Moreover, this kind of Lagrangian has also been investigated in the framework of the Palatini approach [24,28].…”

Section: A the Power Law Lagrangianmentioning

confidence: 99%

f(R) theories of gravity in the Palatini approach matched with observations

2006

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We investigate the viability of f (R) theories in the framework of the Palatini approach as solutions to the problem of the observed accelerated expansion of the universe. Two physically motivated popular choices for f (R) are considered : power law, f (R) = βR n , and logarithmic, f (R) = α ln R. Under the Palatini approach, both Lagrangians give rise to cosmological models comprising only standard matter and undergoing a present phase of accelerated expansion. We use the Hubble diagram of type Ia Supernovae and the data on the gas mass fraction in relaxed galaxy clusters to see whether these models are able to reproduce what is observed and to constrain their parameters. It turns out that they are indeed able to fit the data with values of the Hubble constant and of the matter density parameter in agreement with some model independent estimates, but the today deceleration parameter is higher than what is measured in the concordance ΛCDM model. I. INTRODUCTIONThe Hubble diagram of type Ia supernovae (hereafter SNeIa) [1,2], the anisotropy spectrum of the cosmic microwave background radiation (hereafter CMBR) [3,4,5], the matter power spectrum determined by the large scale distribution of galaxies [6,7] and by the data on the Lyα clouds [8] are all convincing evidences in favour of a new picture of the universe, unexpected only few years ago. According to this nowadays standard scenario, the universe is flat and undergoing an accelerated expansion driven by a mysterious fluid with negative pressure nearly homogeneously distributed and making up to ∼ 70% of the energy content. This exotic component is what is called dark energy, while the model we have just depicted is usually referred to as the concordance model.Even if strongly supported by the bulk of the available astrophysical data, this new picture is not free of problems. Actually, while it is clear how dark energy works, its nature remains an unsolved problem. The simplest explanation claims for the cosmological constant Λ thus leading to the so called ΛCDM model 1 [9]. Although being the best fit to most of the available astrophysical data [4,7], the ΛCDM model is also plagued by many problems on different scales. If interpreted as vacuum energy, Λ is up to 120 orders of magnitudes smaller than the predicted value. Furthermore, one should also solve the coincidence problem, i.e. the nearly equivalence of * Electronic address: capozziello@sa.infn.it, winny@na.infn.it, francaviglia@dm.unito.it 1 It is common in literature to make no distinction between the concordance and the ΛCDM model even if, strictly speaking, in the concordance model the dark energy may also be provided by a different mechanism.

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Curvature Quintessence Matched With Observational Data

Cited by 612 publications

References 21 publications

f(R) cosmology from Noether’s symmetry

f(R) cosmology from Noether’s symmetry

Dark energy exponential potential models as curvature quintessence

f(R) theories of gravity in the Palatini approach matched with observations

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