10
views
0
recommends
+1 Recommend
0 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: found
      Is Open Access

      Delicate f(R) gravity models with disappearing cosmological constant and observational constraints on the model parameters

      Preprint
      , , , , ,

      Read this article at

      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          We study the \(f(R)\) theory of gravity using metric approach. In particular we investigate the recently proposed model by Hu-Sawicki, Appleby \(-\) Battye and Starobinsky. In this model, the cosmological constant is zero in flat space time. The model passes both the Solar system and the laboratory tests. But the model parameters need to be fine tuned to avoid the finite time singularity recently pointed in the literature. We check the concordance of this model with the \(H(z)\) and baryon acoustic oscillation data. We find that the model resembles the \(\Lambda\)CDM at high redshift. However, for some parameter values there are variations in the expansion history of the universe at low redshift.

          Related collections

          Most cited references5

          • Record: found
          • Abstract: found
          • Article: found
          Is Open Access

          A Parameterized Post-Friedmann Framework for Modified Gravity

          We develop a parameterized post-Friedmann (PPF) framework which describes three regimes of modified gravity models that accelerate the expansion without dark energy. On large scales, the evolution of scalar metric and density perturbations must be compatible with the expansion history defined by distance measures. On intermediate scales in the linear regime, they form a scalar-tensor theory with a modified Poisson equation. On small scales in dark matter halos such as our own galaxy, modifications must be suppressed in order to satisfy stringent local tests of general relativity. We describe these regimes with three free functions and two parameters: the relationship between the two metric fluctuations, the large and intermediate scale relationships to density fluctuations and the two scales of the transitions between the regimes. We also clarify the formal equivalence of modified gravity and generalized dark energy. The PPF description of linear fluctuation in f(R) modified action and the Dvali-Gabadadze-Porrati braneworld models show excellent agreement with explicit calculations. Lacking cosmological simulations of these models, our non-linear halo-model description remains an ansatz but one that enables well-motivated consistency tests of general relativity. The required suppression of modifications within dark matter halos suggests that the linear and weakly non-linear regimes are better suited for making complementary test of general relativity than the deeply non-linear regime.
            Bookmark
            • Record: found
            • Abstract: found
            • Article: found
            Is Open Access

            Gauss-Bonnet dark energy

            We propose the Gauss-Bonnet dark energy model inspired by string/M-theory where standard gravity with scalar contains additional scalar-dependent coupling with Gauss-Bonnet invariant. It is demonstrated that effective phantom (or quintessence) phase of late universe may occur in the presence of such term when the scalar is phantom or for non-zero potential (for canonical scalar). However, with the increase of the curvature the GB term may become dominant so that phantom phase is transient and \(w=-1\) barrier may be passed. Hence, the current acceleration of the universe may be caused by mixture of scalar phantom and (or) potential/stringy effects. It is remarkable that scalar-Gauss-Bonnet coupling acts against the Big Rip occurence in phantom cosmology.
              Bookmark
              • Record: found
              • Abstract: found
              • Article: found
              Is Open Access

              Nonlocal Cosmology

              We explore nonlocally modified models of gravity, inspired by quantum loop corrections, as a mechanism for explaining current cosmic acceleration. These theories enjoy two major advantages: they allow a delayed response to cosmic events, here the transition from radiation to matter dominance, and they avoid the usual level of fine tuning; instead, emulating Dirac's dictum, the required large numbers come from the large time scales involved. Their solar system effects are safely negligible, and they may even prove useful to the black hole information problem.
                Bookmark

                Author and article information

                Journal
                22 July 2008
                2008-09-07
                Article
                10.1103/PhysRevD.78.083515
                0807.3445
                9a3c96c7-0c7f-48aa-9fc1-130505dfc86a

                http://arxiv.org/licenses/nonexclusive-distrib/1.0/

                History
                Custom metadata
                Phys.Rev.D78:083515,2008
                16 pages and 9 figures, typos corrected, few references and minor clarifications added, revised version to appera in PRD
                hep-th astro-ph gr-qc hep-ph

                Comments

                Comment on this article