Exploration of Parameters in f(R,T) Gravity and Comparison with Type Ia Supernovae Data

Abstract

The expansion of the Universe in $f(R,T)$ gravity is studied. We consider functions of the form $f(R,T)=R+λT^ε$ where $ε<1$. We find that for all models with $ε<0$, the Universe transitions to exponential growth at late times, just as it does in the standard cosmological model, which corresponds to $ε=0$. It also fits the type Ia supernova data slightly better than the standard cosmological model, without increasing the number of parameters of the theory. In contrast, the fits for $ε>0$ rapidly become worse than the standard cosmological model.

Figures (2)

• Figure 1: The Hubble Parameter as a function of unitless time is shown here. Note that for $\epsilon=0.03$, the solution breaks down at an endpoint. This behavior occurs when $H_\lambda$ attains the value determined by Eq. (\ref{['Break Down H']}) when $\epsilon\in\left(0,\frac{1}{2}\right]$.
• Figure 2: The difference $\Delta m=m_f-m_\Lambda$ between $f(R,T)$ apparent magnitude and the best fit standard $\Lambda$CDM apparent magnitude. The Pantheon binned data is shown here to reduce visual clutter; provided by Scolnic_2018. Both the statistical analysis and fitting were done with the complete dataset.