ΛCDM suitably embedded in f(R) with a non-minimal coupling to matter (2103.01982v1)

Abstract: In this work, we further study a metric modified theory of gravity which contains a non-minimal coupling to matter, more precisely, we assume two functions of the scalar curvature, $f_1$ and $f_2$, where the first one generalises the Hilbert-Einstein action, while the second couples to the matter Lagrangian. On the one hand, assuming a $\Lambda$CDM background, we calculate analytical solutions for the functions $f_1$ and $f_2$. We consider two setups: on the first one, we fix $f_2$ and compute $f_1$ and on the second one, we fix $f_1$ and compute $f_2$. Moreover, we do the analysis for two different energy density contents, a matter dominated universe and a general perfect fluid with a constant equation of state fuelling the universe expansion. On the other hand, we complete our study by performing a cosmographic analysis for $f_1$ and $f_2$. We conclude that the gravitational coupling to matter can drive the accelerated expansion of the universe.