Constraining f(R) gravity by the Large Scale Structure (original) (raw)
Related papers
Cosmography and large scale structure by f (R)-gravity: new results
Advances in Astronomy, 2009
The so-called f (R)-gravity has recently attracted a lot of interest since it could be, in principle, able to explain the accelerated expansion of the Universe without adding unknown forms of dark energy/dark matter but, more simply, extending the General Relativity by generic functions of the Ricci scalar. However, apart several phenomenological models, there is no final f (R)theory capable of fitting all the observations and addressing all the issues related to the presence of dark energy and dark matter. An alternative approach could be to "reconstruct" the form of f (R) starting from data without imposing particular classes of model. Besides, adopting the same philosophy, we take into account the possibility that galaxy cluster masses, estimated at X-ray wavelengths, could be explained, without dark matter, reconstructing the weak-field limit of analytic f (R) models. The corrected gravitational potential, obtained in this approximation, is used to estimate the total mass of a sample of 12 well-shaped clusters of galaxies.
Constraining f(R)-gravity models with recent cosmological data
2020
In this work, we look at the cosmological constraints of some f(R)-modified gravity models such as f(R) = βR (a toy model) and more realistic ones like the Starobinsky and Hu-Sawicki models. We use 236 intermediate-redshift and 123 low-redshift Type 1A Supernovae data obtained from the SDSS-II/SNLS3 Joint Light-curve Analysis (JLA), with absolute magnitudes, for the B-filter, found on the NASA Extragalactic Database (NED). We then develop a Markov Chain Monte-Carlo (MCMC) simulation to find the best fit (firstly to the ΛCDM model), to obtain the cosmological parameters (Ωm and h̄). We then use the concordance model results to constrain the priors for the f(R)-gravity models on the MCMC simulation. We assume a flat universe Ωk = 0 and a radiation density Ωr that is negligible in both the ΛCDM model and f(R)-gravity models. Thus, the only difference between the ΛCDM model and f(R)-gravity models will be dark energy and the arbitrary free parameters. This will tell us if there exist vi...
Large Scale Structure Constraints for a Class of f(R) Theories of Gravity
2013
Over the last few years much attention has been given to the study of modified gravity theories in order to find a more natural explanation for the late time acceleration of the Universe. Nevertheless, a comparison of the matter power spectrum predictions made by these theories with available data has not yet been subjected to a detailed analysis. In the context of f (R) theories of gravity we study the predicted power spectra using both a dynamical systems approach for the background and solving for the matter perturbations without using the quasi-static approximation, comparing the theoretical results with several SDSS Data. The importance of studying the first order perturbed equations by assuming the correct background evolution and the relevance of the initial conditions are also stressed. We determine the statistical significance in relation to the observational data and demonstrate their conflict with existing observations.
Testing an exact f(R) -gravity model at Galactic and local scales
Astronomy and Astrophysics, 2009
Context. The weak field limit for a pointlike source of a f (R) ∝ R 3/2 -gravity model is studied. Aims. We aim to show the viability of such a model as a valid alternative to GR + dark matter at Galactic and local scales. Methods. Without considering dark matter, within the weak field approximation, we find general exact solutions for gravity with standard matter, and apply them to some astrophysical scales, recovering the consistency of the same f (R)-gravity model with cosmological results.
Theoretical and observational constraints of viablef(R)theories of gravity
Physical Review D, 2016
Modified gravity has attracted much attention over the last few years and remains a potential candidate for dark energy. In particular, the so-called viable f (R) gravity theories, which are able to both recover General Relativity (GR) and produce late-time cosmic acceleration, have been widely studied in recent literature. Nevertheless, extended theories of gravity suffer from several shortcomings which compromise their ability to provide realistic alternatives to the standard cosmological ΛCDM Concordance model. We address the existence of cosmological singularities and the conditions that guarantee late-time acceleration, assuming reasonable energy conditions for standard matter in the so-called Hu-Sawicki f (R) model, currently among the most widely studied modifications to General Relativity. Then using the Supernovae Ia Union 2.1 catalogue, we further constrain the free parameters of this model. The combined analysis of both theoretical and observational constraints sheds some light on the viable parameter space of these models and the form of the underlying effective theory of gravity.
Cluster constraints on f(R) gravity
Physical Review D, 2009
Modified gravitational forces in models that seek to explain cosmic acceleration without dark energy typically predict deviations in the abundance of massive dark matter halos. We conduct the first, simulation calibrated, cluster abundance constraints on a modified gravity model, specifically the modified action f (R) model. The local cluster abundance, when combined with geometric and high redshift data from the cosmic microwave background, supernovae, H0 and baryon acoustic oscillations, improve previous constraints by nearly 4 orders of magnitude in the field amplitude. These limits correspond to a 2 order of magnitude improvement in the bounds on the range of the force modification from the several Gpc scale to the tens of Mpc scale.
Cosmological implications of a viable non-analytical f (R)-gravity model
2011
Power-law corrections (having the exponent strictly between 2 and 3) to the Einstein-Hilbert action yield an extended theory of gravity which is consistent with Solar-System tests and properly reproduces the main phases of the Universe thermal history. We find two distinct constraints for the characteristic length scale of the model: a lower bound from the Solar-System test and an upper bound by requiring the existence of the matter-dominated era. We also show how the extended framework can accommodate the existence of an early de Sitter phase. Within the allowed range of characteristic length scales, the relation between the expansion rate and the energy scale of inflation is modified, yielding a value of the rate several orders of magnitude smaller than in the standard picture. The observational implication of this fact is that a tiny value of the tensor-to-scalar ratio is expected in the extended framework. The suppression of primordial tensor modes also implies that the inflationary scale can be made arbitrarily close to the Planck one according to the current limits. Finally, an analysis of the propagation of gravitational waves on a Robertson-Walker background is addressed.
Journal of Cosmology and Astroparticle …, 2010
In this work, we study the large scale structure formation in the modified gravity in the framework of Palatini formalism and compare the results with the equivalent smooth dark energy models as a tool to distinguish between these models. Through the inverse method, we reconstruct the dynamics of universe, modified gravity action and the structure formation indicators like the screened mass function and gravitational slip parameter. Consequently, we extract the matter density power spectrum for these two models in the linear regime and show that the modified gravity and dark energy models predictions are slightly different from each other at large scales. It is also shown that the growth index in the modified gravity unlike to the dark energy models is a scale dependent parameter. We also compare the results with those from the modified gravity in the metric formalism. The modification on the structure formation can also change the CMB spectrum at large scales however due to the cosmic variance it is hard to detect this signature. We show that a large number of SNIa data in the order of 2000 will enable us to reconstruct the modified gravity action with a suitable confidence level and test the cosmic acceleration models by the structure formation.