84 citations · 656 across the 80 of their papers we have counts for
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Flat limits of curved interacting cosmic fluids
Spiros Cotsakis, Georgia Kittou
We study curved isotropic cosmologies filled with two interacting fluids near their time singularities. We find that a number of these universes asymptote to flat limits in the sen…
Asymptotic vacua with higher derivatives
Spiros Cotsakis, Seifedine Kadry, Georgios Kolionis +1
We study limits of vacuum, isotropic universes in the full, effective, four-dimensional theory with higher derivatives. We show that all flat vacua as well as general curved ones a…
Generic regular universes in higher order gravity theories
Spiros Cotsakis, Dimitrios Trachilis, Antonios Tsokaros
We review recent results on the Cauchy-Kowalevsky structure of theories with higher derivatives in vacuum. We prove genericity of regularity of solutions under the assumption of an…
Asymptotic states of generalized universes with higher derivatives
Spiros Cotsakis, Georgios Kolionis, Antonios Tsokaros
We review ongoing research related to the asymptotic dynamics of isotropic universes in theories with higher derivatives, especially near the initial singularity. We treat two majo…
Limits of isotropic universes with interacting fluids
Spiros Cotsakis, Georgia Kittou
We find various asymptotic limits of universes containing two interacting fluids which interact and exchange energy. We study the finite-time singularities that may develop in thes…
Series expansions and sudden singularities
John D. Barrow, S. Cotsakis, A. Tsokaros
We construct solutions of the Friedmann equations near a sudden singularity using generalized series expansions for the scale factor, the density, and the pressure of the fluid con…
Asymptotic Poincaré compactification and finite-time singularities
Spiros Cotsakis
We provide an extension of the method of asymptotic decompositions of vector fields with finite-time singularities by applying the central extension technique of Poincaré to the do…