Constraints on f(R) cosmologies from strong gravitational lensing systems

TL;DR

This study uses strong gravitational lensing data, combined with CMB and BAO observations, to constrain f(R) gravity models, finding results consistent with the standard Lambda Cold Dark Matter model within 1 sigma.

Contribution

It provides new constraints on f(R) gravity models using lensing data combined with CMB and BAO, testing their viability against observational evidence.

Findings

Lensing data alone constrains f(R) parameters close to standard cosmology.

Combined data yields tighter bounds, consistent with Lambda CDM.

Results favor standard cosmology within 1 sigma confidence level.

Abstract

f(R) gravity is thought to be an alternative to dark energy which can explain the acceleration of the universe. It has been tested by different observations including type Ia supernovae (SNIa), the cosmic microwave background (CMB), the baryon acoustic oscillations (BAO) and so on. In this Letter, we use the Hubble constant independent ratio between two angular diameter distances $D=D_{ls}/D_s$ to constrain f(R) model in Palatini approach $f(R)=R-\alpha H^2_0(-\frac{R}{H^2_0})^\beta$. These data are from various large systematic lensing surveys and lensing by galaxy clusters combined with X-ray observations. We also combine the lensing data with CMB and BAO, which gives a stringent constraint. The best-fit results are $(\alpha,\beta)=(-1.50,0.696)$ or $(\Omega_m,\beta)=(0.0734,0.696)$ using lensing data only. When combined with CMB and BAO, the best-fit results are $(\alpha,\beta)=(-3.75,0.0651)$ or $(\Omega_m,\beta)=(0.286,0.0651)$. If we further fix $\beta=0$ (corresponding to $\Lambda$CDM), the best-fit value for $\alpha$ is $\alpha$=$-4.84_{-0.68}^{+0.91}(1\sigma)_{-0.98}^{+1.63}(2\sigma)$ for the lensing analysis and $\alpha$=$-4.35_{-0.16}^{+0.18}(1\sigma)_{-0.25}^{+0.3}(2\sigma)$ for the combined data, respectively. Our results show that $\Lambda$CDM model is within 1$\sigma$ range.