Quadratic gravity with Weyl-squared and Ricci-squared terms produces PPN parameters that equal their GR values except for exponentially decaying corrections, with gamma identically 1 when the two mode masses are equal, yielding solar-system lower bounds m_R, m_W greater than or equal to 23 per AU.
Linearized f(R) Gravity: Gravitational Radiation & Solar System Tests
6 Pith papers cite this work. Polarity classification is still indexing.
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abstract
We investigate the linearized form of metric f(R)-gravity, assuming that f(R) is analytic about R = 0 so it may be expanded as f(R) = R + a_2 R^2/2 + ... . Gravitational radiation is modified, admitting an extra mode of oscillation, that of the Ricci scalar. We derive an effective energy-momentum tensor for the radiation. We also present weak-field metrics for simple sources. These are distinct from the equivalent Kerr (or Schwarzschild) forms. We apply the metrics to tests that could constrain f(R). We show that light deflection experiments cannot distinguish f(R)-gravity from general relativity as both have an effective post-Newtonian parameter \gamma = 1. We find that planetary precession rates are enhanced relative to general relativity; from the orbit of Mercury we derive the bound |a_2| < 1.2 \times 10^18 m^2. Gravitational wave astronomy may be more useful: considering the phase of a gravitational waveform we estimate deviations from general relativity could be measurable for an extreme-mass-ratio inspiral about a 10^6 M_sol black hole if |a_2| > 10^17 m^2, assuming that the weak-field metric of the black hole coincides with that of a point mass. However Eot-Wash experiments provide the strictest bound |a_2| < 2 \times 10^-9 m^2. Although the astronomical bounds are weaker, they are still of interest in the case that the effective form of f(R) is modified in different regions, perhaps through the chameleon mechanism. Assuming the laboratory bound is universal, we conclude that the propagating Ricci scalar mode cannot be excited by astrophysical sources.
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In Hu-Sawicki f(R) gravity the redshift-space bispectrum monopole and quadrupole show 2-8% deviations from GR at z=0.7 and k~0.3 h/Mpc with forecasted SNR of 30 and 15 for Euclid.
Generalized hybrid metric-Palatini gravity propagates a massless spin-2 mode and two massive scalars in the weak field; stability requires algebraic conditions on f derivatives at flat space, and planetary data constrain the scalar masses in a hierarchical regime.
A systematic mapping is derived from GUP parameters in minimal-length quantum theory to higher-order curvature coefficients in extended gravity, with an application yielding an upper bound on the minimal measurable length via light deflection corrections.
A review summarizing modified theories of gravity, their effects on compact objects, existing bounds from astrophysical observations, and the promise of future gravitational wave tests for strong-field gravity.
A comprehensive review of modified gravity theories and their cosmological consequences, including a parameterized post-Friedmannian formalism for constraining deviations from General Relativity.
citing papers explorer
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Parameterized Post-Newtonian Analysis of Quadratic Gravity and Solar System Constraints
Quadratic gravity with Weyl-squared and Ricci-squared terms produces PPN parameters that equal their GR values except for exponentially decaying corrections, with gamma identically 1 when the two mode masses are equal, yielding solar-system lower bounds m_R, m_W greater than or equal to 23 per AU.
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Tracing Signatures of Modified Gravity in Redshift-Space Galaxy Bispectrum Multipoles: Prospects for Euclid
In Hu-Sawicki f(R) gravity the redshift-space bispectrum monopole and quadrupole show 2-8% deviations from GR at z=0.7 and k~0.3 h/Mpc with forecasted SNR of 30 and 15 for Euclid.
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Another Look at the Weak-Field Limit of Generalized Hybrid Metric-Palatini Gravity
Generalized hybrid metric-Palatini gravity propagates a massless spin-2 mode and two massive scalars in the weak field; stability requires algebraic conditions on f derivatives at flat space, and planetary data constrain the scalar masses in a hierarchical regime.
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From minimal-length quantum theory to modified gravity
A systematic mapping is derived from GUP parameters in minimal-length quantum theory to higher-order curvature coefficients in extended gravity, with an application yielding an upper bound on the minimal measurable length via light deflection corrections.
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Testing General Relativity with Present and Future Astrophysical Observations
A review summarizing modified theories of gravity, their effects on compact objects, existing bounds from astrophysical observations, and the promise of future gravitational wave tests for strong-field gravity.
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Modified Gravity and Cosmology
A comprehensive review of modified gravity theories and their cosmological consequences, including a parameterized post-Friedmannian formalism for constraining deviations from General Relativity.