Constraints on scalar-tensor theories from observations

We study the dynamical description of scalar-tensor gravity by performing the best-fit analysis for two cases of exponential and power-law form of the potential and scalar field function coupled to the curvature. The models are then tested against observational data. The results show that in both scenarios the Universe undergoes an acceleration expansion period and the geometrical equivalent of dark energy is associated with a time-dependent equation of state.

Figure 1

The best-fitted one dimension likelihood and confidence level for $\alpha$, $\beta$, and $H_0$ for exponential functions.

Figure 2

The best-fitted two dimension likelihood and confidence level for $\alpha$, $\beta$, and $H_0$ for exponential functions.

Figure 3

The best-fitted two dimension likelihood and confidence level for $\alpha$, $\beta$, and $H_0$ for power-law functions.

Figure 4

The best-fitted two dimension likelihood and confidence level for $\alpha$, $\beta$, and $H_0$ for power-law functions.

Figure 5

The best-fitted distance modulus $\mu (z)$ plotted as function of redshift for $F(\varphi )$ and $V$ (left) exponential, (right) power-law.

Figure 6

The best-fitted effective EoS parameter plotted as function of redshift for $F(\varphi )$ and $V$ (left) exponential, (right) power-law.

Figure 7

The best-fitted $H(z)$ plotted as function of redshift for $F(\varphi )$ and $V$ (left) exponential, (right) power-law.

Figure 8

The best-fitted reconstructed $F(\varphi )$ and $V(\varphi )$ plotted as function of redshift for (left) exponential forms, (right) power-law forms.