Late Time Cosmological Evolution in f(R) theories with Ordinary and Collisional Matter

Understand

We study the late time cosmological evolution of $f(R)$ theories of modified gravity, with the matter content of the universe being that of collisional self interacting matter.

• We assume that the universe is described by a flat Friedmann-Lemaitre-Robertson-Walker metric and that it is matter and dark energy dominated.
• The results of our numerical analysis for a collisional matter $f(R)$ theory are compared with those resulting from pressure-less matter $f(R)$ theory and from the $\mathrm{\Lambda}\mathrm{CDM}$ model.
• As we shall demonstrate, the resulting picture can vary from model to model, indicating that the effect of collisional matter in $f(R)$ theories is strongly model dependent.