Testing power-law cosmology with galaxy clusters

TL;DR

This study tests power-law cosmology using galaxy cluster X-ray gas mass fractions, finding a best-fit power index of about 1.14, supporting the model's consistency with observations.

Contribution

It constrains the power-law index in cosmology using galaxy cluster data, providing a new observational test for power-law cosmological models.

Findings

Best-fit power index α = 1.14 ± 0.05 for an open universe

Flat and closed models are not ruled out at high confidence

X-ray gas mass fractions offer a complementary test of power-law cosmology

Abstract

Power-law cosmologies, in which the cosmological scale factor evolves as a power law in the age, $a \propto t^{\alpha}$ with $\alpha \ga 1$, regardless of the matter content or cosmological epoch, is comfortably concordant with a host of cosmological observations.} {In this article, we use recent measurements of the X-ray gas mass fractions in clusters of galaxies to constrain the $\alpha$ parameter with curvature $k = \pm1, 0$. We find that the best fit happens for an open scenario with the power index $\alpha = 1.14 \pm 0.05$, though the flat and closed model can not be rule out at very high confidence level.} {Our results are in agreement with other recent analyses and show that the X-ray gas mass fraction measurements in clusters of galaxies provide a complementary test to the power law cosmology.