Models of f(R) Cosmic Acceleration that Evade Solar-System Tests

By Wayne Hu, I. Sawicki. 2007

1,399 citations recorded by the source corpus.

We study a class of metric-variation fRmodels that accelerates the expansion without a cosmological constant and satisfies both cosmological and solar-system tests in the small-field limit of the parameter space. Solar-system tests alone place only weak bounds on these models, since the additional scalar degree of freedom is locked to the high-curvature general-relativistic prediction across more than 25 orders of magnitude in density, out through the solar corona. This agreement requires that the galactic halo be of sufficient extent to maintain the galaxy at high curvature in the presence of the low-curvature cosmological background. If the galactic halo and local environment in fRmodels do not have substantially deeper potentials than expected inCDM , then cosmological field amplitudes jfRj * 10 � 6 will cause the galactic interior to evolve to low curvature during the acceleration epoch. Viability of large-deviation models therefore rests on the structure and evolution of the galactic halo, requiring cosmological simulations of fRmodels, and not directly on solar-system tests. Even small deviations that conservatively satisfy both galactic and solar-system constraints can still be tested by future, percent- level measurements of the linear power spectrum, while they remain undetectable to cosmological- distance measures. Although we illustrate these effects in a specific class of models, the requirements on fRare phrased in a nearly model-independent manner.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/229863477f52634231607ac6629124a7c43f44bc

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Citations in the corpus

Galileon Cosmology (2009, background): “Theories of f(R) gravity [6] rely on the chameleon effect to ensure consistency with solar system tests [7].”
Testing modified gravity at cosmological distances with LISA standard sirens (2019, methodology): “e order of percent for these scenarios. [where fR0 (fR)0 is the present value of fR] as well as n’ f0 R fR 0 : (3.11) Adopting the particular functional form for fproposed by Hu and Sawicki (HS) [66] f(R) ’ 2 fR0R~n+1 0 nR~ n~ ; (3.12) one obtains n’ 3(~n+ 1) m (4 3 m) : (3.13) These relations rem”
Evolution of the f σ 8 tension with the Planck 15 / Λ CDM determination and implications for modified gravity theories (2018, background): “[35] Wayne Hu and Ignacy Sawicki, “Models of f(R) Cos-”
The Subaru FMOS galaxy redshift survey (FastSound). IV. New constraint on gravity theory from redshift space distortions at z ∼ 1.4 (2015, background): “A notable example is givenby Hu & Sawicki (2007) f(R) =R−λRc (R/Rc) 2n (R/Rc)2n +1 , (25) where n, λ and Rc are positive constants.”