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A complete analysis of the dynamics of the Hu-Sawicki modification to General Relativity is presented. In particular, the full phase-space is given for the case in which the model parameters are taken to be n=1, c1=1, and several stable de Sitter equilibrium points together with an unstable matter-like point are identified. We find that if the cosmological parameters are chosen to take on their Lambda CDM values today, this results in a universe which, until very low redshifts, is dominated by an equation of state parameter equal t1/3, leading to an expansion history very different from Lambda CDM. We demonstrate that this problem can be resolved by choosing Lambda CDM initial conditions at high redshifts and integrating the equations to the present day.
One of the so-called viable modified gravities is analyzed. This kind of gravity theories are characterized by a well behavior at local scales, where General Relativity is recovered, while the modified terms become important at the cosmological level
Modified gravity has attracted much attention over the last few years and remains a potential candidate for dark energy. In particular, the so-called viable f(R) gravity theories, which are able to both recover General Relativity (GR) and produce lat
In literature there is a model of modified gravity in which the matter Lagrangian is coupled to the geometry via trace of the stress-energy momentum tensor $T=T_{mu}^{mu}$. This type of modified gravity is called as $f(R,T)$ in which $R$ is Ricci sca
Modified f(R) gravity is one of the most promising candidates for dark energy, and even for the unification of the whole cosmological evolution, including the inflationary phase. Within this class of theories, the so-called viable modified gravities
In $f(R)$ gravity and Brans-Dicke theory with scalar potentials, we study the structure of neutron stars on a spherically symmetric and static background for two equations of state: SLy and FPS. In massless BD theory, the presence of a scalar couplin