Abstract
We summarize the effective field theory of dark energy construction to explore observable predictions of linear Horndeski theories. We review the diagnostic of these theories on the correlation of the large-scale structure phenomenological functions: the effective Newton constant, the light deflection parameter, and the growth function of matter perturbations. We take this opportunity to discuss the evolution of the bounds the propagation speed of gravitational waves has undergone and use the most restrictive one to update the diagnostic.
Highlights
Models incorporating an extra scalar degree of freedom to the Einstein–Hilbert action to explain the accelerated phases of the universe’s expansion are numerous, and one is tempted to ask whether a way to describe all these theories in a common framework exists
Procedure allows one to make sure the σ8 (t) of the model considered agrees with the normalization imposed by Cosmic Microwave Background (CMB) constraints in the past while its evolution is free to be driven by the Modified Gravity (MG) effects
Please note that the above explains why, by definition, no model will be able to exhibit μ < 1 at redshift zero. It is this distinction between the components that allows us to understand the new features on the EDE and Early Modified Gravity (EMG) scenario
Summary
Models incorporating an extra scalar degree of freedom to the Einstein–Hilbert action to explain the accelerated phases of the universe’s expansion are numerous, and one is tempted to ask whether a way to describe all these theories in a common framework exists. Impose the speed of gravitational waves to be bounded extremely close to that of light at low redshifts This could be a stringent constraint for MG and models adding one extra scalar degree of freedom to General Relativity (GR) [10,11,12,13,14,15]. We update the diagnostic the correlation of LSS observables produce on linear Horndeski theories, this time, with the speed of gravitational waves equal to that of light at all times
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