Phase-resolved field-space distance bounds for non-inflationary smoothing yield a master lower bound on ε_ek and imply ultra-fast-roll ekpyrosis or modified bounces to match observed red-tilted perturbations.
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Accelerating uni- verses with scaling dark matter
22 Pith papers cite this work. Polarity classification is still indexing.
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abstract
Friedmann-Robertson-Walker universes with a presently large fraction of the energy density stored in an $X$-component with $w_X<-1/3$, are considered. We find all the critical points of the system for constant equations of state in that range. We consider further several background quantities that can distinguish the models with different $w_X$ values. Using a simple toy model with a varying equation of state, we show that even a large variation of $w_X$ at small redshifts is very difficult to observe with $d_L(z)$ measurements up to $z\sim 1$. Therefore, it will require accurate measurements in the range $1<z<2$ and independent accurate knowledge of $\Omega_{m,0}$ (and/or $\Omega_{X,0}$) in order to resolve a variable $w_X$ from a constant $w_X$.
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