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

Abstract

In this paper, we implement a new model-independent 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 fgas is depleted with respect to the universal baryonic mean) and one varying with redshift. We also consider the influence of different H0 estimates on our results. We look for a variation of c, given by c(z) = c0(1 + c1z). It is found a degeneracy between our final results on c variation and the assumptions on gas mass fraction depletion factor. Most of our analyses indicate negligible variation of the speed of light.

Constraining a possible time-variation of the speed of light along with the fine-structure constant using strong gravitational lensing and Type Ia supernovae observations

“…On the other hand, in Ref. [53] a new method to test the invariance of c as a function of redshift combining the measurements of galaxy cluster gas mass fraction, H(z)-data from cosmic chronometers, and SNe Ia, is implemented. The analyses indicated a negligible variation of c (see more in [54] and the references therein).…”

Testing a varying-$Λ$ model for dark energy within CPC framework

“…Refs. [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28] in the recent literature. This is a rather controversial topic [29,30,31].…”

“…Further open problems of relativistic cosmology are the Hubble tension [47], the S8 tension [42], and discrepancies related to the distribution of cold dark matter [48]. This context opens up the possibility of analyzing the consequences of admitting varying physical constants both from theoretical side-e.g., [2,28,49,50]-and in the data-fitting or observational approach-e.g., [16,21,26,27,51,52,53].…”

“…In fact, recent studies of extensions of the general relativity theory proposes that fundamental couplings of physics are expected to vary. As a few examples we mention models involving variations of the fine-structure constant α [54,55,56,57,58,59,60,61,62], models admitting variation of the Newton's gravitational constant G [63,64,65,66,67,68,69,70], and models addressing the variation of the speed of light c [71,72,73,74,75,76,77,78,79,80,21,81,82,83,84,85,29,86]. The main feature of these works is the fact that they consider only one of the aforementioned couplings as a function of the time, while disregarding possible variations of the others.…”