In f(R,T) = R + F(T) gravity, nonlinear F makes the averaged modified term differ from F at averaged T, invalidating the common unity-ratio assumption and giving dust nonzero proper pressure.
Einstein's Universe: Cosmological structure formation in numerical relativity
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abstract
We perform large-scale cosmological simulations that solve Einstein's equations directly via numerical relativity. Starting with initial conditions sampled from the cosmic microwave background, we track the emergence of a cosmic web without the need for a background cosmology. We measure the backreaction of large-scale structure on the evolution of averaged quantities in a matter-dominated universe. Although our results are preliminary, we find the global backreaction energy density is of order $10^{-8}$ compared to the energy density of matter in our simulations, and is thus unlikely to explain accelerating expansion under our assumptions. Sampling scales above the homogeneity scale of the Universe ($100-180\,h^{-1}$Mpc), in our chosen gauge, we find $2-3\%$ variations in local spatial curvature.
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astro-ph.CO 3years
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UNVERDICTED 3representative citing papers
Full-GR simulations find that inhomogeneous curvature produces only sub-dominant systematic offsets in growth-rate measurements from magnitude fluctuations at z ≲ 0.2 relative to current statistical errors.
Numerical simulations show that inhomogeneities in a LambdaCDM universe can lead some observers to infer evolving dark energy parameters consistent with DESI at 2-sigma.
citing papers explorer
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Cosmological Averaging in Nonminimally Coupled Gravity
In f(R,T) = R + F(T) gravity, nonlinear F makes the averaged modified term differ from F at averaged T, invalidating the common unity-ratio assumption and giving dust nonzero proper pressure.
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Impact of inhomogeneous curvature on growth rate measurements from magnitude fluctuations
Full-GR simulations find that inhomogeneous curvature produces only sub-dominant systematic offsets in growth-rate measurements from magnitude fluctuations at z ≲ 0.2 relative to current statistical errors.
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On the potential for inhomogeneities to mimic an evolving dark energy
Numerical simulations show that inhomogeneities in a LambdaCDM universe can lead some observers to infer evolving dark energy parameters consistent with DESI at 2-sigma.