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arXiv · 1709.08709

Subpercent Accurate Fitting of Modified Gravity Growth

Mikhail Denissenya·Eric V. Linder
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Abstract

Adding to our previous method for dealing with gravitational modifications at redshift $z\gtrsim3$ through a single parameter, we investigate treatment of lower redshift modifications to linear growth observables. We establish subpercent accurate fits to the redshift space distortion observable $f\sigma_8(a)$ using two parameters binned in redshift, testing the results for modifications with time dependence that rises, falls, is nonmonotonic, is multipeaked, and corresponds to $f(R)$ and braneworld gravity. The residuals are then propagated to cosmological parameter biases for DESI observations, and found to cause a shift in the dark energy joint confidence contour by less than the equivalent of $\sim0.1\sigma$. The proposed 2--3 parameter modified gravity description also can reveal physical characteristics of the underlying theory.

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Mikhail Denissenya, Eric V. Linder. 2017-09-25. Subpercent Accurate Fitting of Modified Gravity Growth. https://doi.org/10.1088/1475-7516%2F2017%2F11%2F052

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