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arXiv · 1906.10480

Late-times asymptotic equation of state for a class of nonlocal theories of gravity

Leonardo Giani·Oliver Fabio Piattella
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Abstract

We investigate the behavior of the asymptotic late-times effective equation of state for a class of nonlocal theories of gravity. These theories modify the Einstein-Hilbert Lagrangian introducing terms containing negative powers of the d'Alembert operator acting on the Ricci scalar. We find that imposing vanishing initial conditions for the nonlocal content during the radiation-dominated epoch implies the same asymptotic late-times behavior for most of these models. In terms of the effective equation of state of the universe, we find that asymptotically $\omega_{ \rm eff} \rightarrow -1$, approaching the value given by a cosmological constant. On the other hand, unlike in the case of $\Lambda$CDM, the Hubble factor is a monotonic growing function that diverges asymptotically. We argue that this behavior is not a coincidence and discuss under which conditions this is to be expected in these nonlocal models.

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Leonardo Giani, Oliver Fabio Piattella. 2019-06-25. Late-times asymptotic equation of state for a class of nonlocal theories of gravity. https://doi.org/10.1103/physrevd.100.123508

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