Structure formation in modified gravity models

  title={Structure formation in modified gravity models},
  author={Kazuya Koyama},
  journal={Journal of Cosmology and Astroparticle Physics},
  pages={017 - 017}
  • K. Koyama
  • Published 10 January 2006
  • Physics
  • Journal of Cosmology and Astroparticle Physics
We study structure formation in phenomenological models in which the Friedmann equation receives a correction of the form Hα/rc2 − α, to realize an accelerated expansion without dark energy. In order to address structure formation in these models, we construct simple covariant gravitational equations which give the modified Friedmann equation with α = 2/n, where n is an integer. For n = 2, the underlying theory is known as a five-dimensional (5D) braneworld model (the DGP model). Thus the… 
Non-linear Evolution of Matter Power Spectrum in Modified Theory of Gravity
We present a formalism to calculate the nonlinear matter power spectrum in modified gravity models that explain the late-time acceleration of the Universe without dark energy. Any successful modified
Large scale structures in the kinetic gravity braiding model that can be unbraided
We study cosmological consequences of a kinetic gravity braiding model, which is proposed as an alternative to the dark energy model. The kinetic braiding model we study is characterized by a
Spherical collapse in modified gravity with the Birkhoff theorem
We study structure formation in a phenomenological model of modified gravity which interpolates between Acold dark mtter (ACDM) and Dvali-Gabadadze-Porrati (DGP) gravity. In our model, the Friedmann
New measures to test modified gravity cosmologies
The observed accelerated expansion of the Universe may be explained by dark energy or the breakdown of general relativity (GR) on cosmological scales. When the latter case, a modified gravity
Consistency test of general relativity from large scale structure of the universe
We construct a consistency test of General Relativity (GR) on cosmological scales. This test enables us to distinguish between the two alternatives to explain the late-time accelerated expansion of
Cosmological perturbations on the phantom brane
We obtain a closed system of equations for scalar perturbations in a multi-component braneworld. Our braneworld possesses a phantom-like equation of state at late times, weff < −1, but no big-rip
Towards precision constraints on gravity with the Effective Field Theory of Large-Scale Structure
We compare analytical computations with numerical simulations for dark-matter clustering, in general relativity and in the normal branch of DGP gravity (nDGP). Our analytical frameword is the
N-body simulations of alternative gravity models
Theories in which gravity is weaker on cosmological scales have been proposed to explain the observed acceleration of the universe. The nonlinear regime in such theories is not well studied, though
Exponential Potentials and Attractor Solution of Dilatonic Cosmology
Abstract We present the scalar-tensor gravitational theory with an exponential potential in which Pauli metric is regarded as the physical space-time metric. We show that it is essentially equivalent
Constraining modified gravity and growth with weak lensing
The idea that we live in a Universe undergoing a period of acceleration is a new, yet strongly held, notion in cosmology. As this can, potentially, be explained with a modification to general


Structure formation in the Dvali–Gabadadze–Porrati cosmological model
The DGP brane-world model provides an alternative to the standard LCDM cosmology, in which the late universe accelerates due to a modification of gravity rather than vacuum energy. The cosmological
Ghosts in the self-accelerating brane universe
We study the spectrum of gravitational perturbations about a vacuum de Sitter brane with the induced 4D Einstein-Hilbert term, in a 5D Minkowski spacetime (DGP model). We consider solutions that
The Einstein equations on the 3-brane world
We carefully investigate the gravitational equations of the brane world, in which all the matter forces except gravity are confined on the 3-brane in a 5-dimensional spacetime with $Z_2$ symmetry. We
Weak gravity in the Dvali-Gabadadze-Porrati braneworld model
We analyze the weak gravity in the braneworld model proposed by Dvali-Gabadadze-Porrati, in which the unperturbed background spacetime is given by five dimensional Minkowski bulk with a brane which
Strong Interactions and Stability in the DGP Model
The model of Dvali, Gabadadze, and Porrati (DGP) gives a simple geometrical setup in which gravity becomes 5-dimensional at distances larger than a length scale lambda(DGP). We show that this theory
Nonperturbative Continuity in Graviton Mass versus Perturbative Discontinuity
We address the question whether a graviton could have a small nonzero mass. The issue is subtle for two reasons: there is a discontinuity in the mass in the lowest tree-level approximation, and,
On brane world cosmological perturbations
We discuss the scalar cosmological perturbations in a 3-brane world with a 5D bulk. We first show explicitly how the effective perturbed Einstein equations on the brane (involving the Weyl fluid) are
Effective gravitational equations on a brane world with induced gravity
We present the effective equations to describe the four-dimensional gravity of a brane world, assuming that a five-dimensional bulk spacetime satisfies the Einstein equations and gravity is confined
Cosmological perturbations of brane-induced gravity and the van Dam-Veltman-Zakharov discontinuity on Friedmann-Lemaitre-Robertson-Walker space-times
We investigate the cosmological perturbations of the brane-induced (Dvali-Gabadadze-Porrati) model which exhibits a van Dam-Veltman-Zakharov (vDVZ) discontinuity when linearized over a Minkowski