Modified-Source Gravity and Cosmological Structure Formation

Abstract

One way to account for the acceleration of the universe is to modify general relativity, rather than introducing dark energy. Typically, such modifications introduce new degrees of freedom. It is interesting to consider models with no new degrees of freedom, but with a modified dependence on the conventional energy-momentum tensor; the Palatini formulation of $f(R)$ theories is one example. Such theories offer an interesting testing ground for investigations of cosmological modified gravity. In this paper we study the evolution of structure in these ``modified-source gravity'' theories. In the linear regime, density perturbations exhibit scale dependent runaway growth at late times and, in particular, a mode of a given wavenumber goes nonlinear at a higher redshift than in the standard $\Lambda$CDM model. We discuss the implications of this behavior and why there are reasons to expect that the growth will be cut off in the nonlinear regime. Assuming that this holds in a full nonlinear analysis, we briefly describe how upcoming measurements may probe the differences between the modified theory and the standard $\Lambda$CDM model.

22 pages, 6 figures, uses iopart style

Cited by in corpus (110)

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• Modified Gravity and Cosmology
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• Testing General Relativity in Cosmology
• Observational signatures of f(R) dark energy models that satisfy cosmological and local gravity constraints
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• Construction of cosmologically viable f(G) gravity models
• Solar System constraints to general f(R) gravity
• The pattern of growth in viable f(R) cosmologies
• Dynamics of Linear Perturbations in f(R) Gravity
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• Dynamics of scalar perturbations in f(R,T) gravity
• Modified gravity models of dark energy
• Phantom crossing, equation-of-state singularities, and local gravity constraints in f(R) models
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• Effective gravitational couplings for cosmological perturbations in the most general scalar-tensor theories with second-order field equations
• Probing the theory of gravity with gravitational lensing of gravitational waves and galaxy surveys
• f(R) gravity theories in Palatini formalism: cosmological dynamics and observational constraints
• Constraints on scalar-tensor models of dark energy from observational and local gravity tests
• On the stability of the cosmological solutions in f(R,G) gravity
• Solar system constraints on f(G) gravity models
• Limits of Quasi-Static Approximation in Modified-Gravity Cosmologies
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• Classifying and avoiding singularities in the alternative gravity dark energy models
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• Density perturbations in f(R) gravity theories in metric and Palatini formalisms
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• Validation of Energy Conditions in Wormhole Geometry within Viable $f(R)$ Gravity
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• Cosmological perturbations in theories with non-minimal coupling between curvature and matter
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• How (Not) to Palatini
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• $f(R)$ gravity constrained by PPN parameters and stochastic background of gravitational waves
• Rational approximations of $f(R)$ cosmography through Padé polynomials
• The effect of modified gravity on weak lensing
• Dynamical Instability of Spherical Star in $f(R,T)$ gravity
• Parameterizing the Effect of Dark Energy Perturbations on the Growth of Structures
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• Testing for dynamical dark energy models with redshift-space distortions
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• Cosmological evolution, future singularities, Little Rip and Pseudo-Rip in viable f(R) theories and their scalar-tensor counterpart
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• Cosmological dynamics of interacting dark energy and dark matter in viable models of f(R) gravity
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• Observational tests of a two parameter power-law class modified gravity in Palatini formalism
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