A search for the variation of speed of light using galaxy cluster gas mass fraction measurements

Understand

In this paper, we implement a new method to test the invariance of the speed of light ($c$) as a function of redshift, by combining the measurements of galaxy cluster gas mass fraction, $H(z)$ from cosmic chronometers, and Type-Ia supernovae (SNe Ia).

• In our analyses, we consider both a constant depletion factor (which corresponds to the ratio by which the cluster gas mass fraction is depleted with respect to the universal baryonic mean) and one varying with redshift.
• We also consider the influence of different $H_0$ estimates on our results.
• We look for a variation of $c$, given by $c(z)=c_0(1+c_1z)$.