Astronomy & Astrophysics

A&A 483, 15-18 (2008)
DOI: 10.1051/0004-6361:20077797

Testing power-law cosmology with galaxy clusters

Zong-Hong Zhu^{1, 2}, M. Hu¹, J. S. Alcaniz^{3, 4}, and Y.-X. Liu⁵

¹ Department of Astronomy, Beijing Normal University, Beijing 100875, PR China
e-mail: zhuzh@bnu.edu.cn
² Institut d'Astrophysique Spatiale (IAS), CNRS & Univ. Paris-Sud, Bâtiment 121, 91405 Orsay, France
³ Departamento de Astronomia, Observatório Nacional, 20921-400, Rio de Janeiro, Brasil
e-mail: alcaniz@on.br
⁴ Instituto Nacional de Pesquisas Espaciais/CRN, 59079-740, Natal-RN, Brazil
⁵ The College of Applied Science, Beijing University of Technology, Beijing 100022, PR China

(Received 5 May 2007 / Accepted 20 December 2007)

Abstract
Aims. Power-law cosmologies, in which the cosmological scale factor evolves as a power law in time, $a \propto t^{\alpha}$ with $\alpha \ga 1$ , regardless of the matter content or cosmological epoch, is comfortably concordant with a host of cosmological observations.
Methods. 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 $k = \pm1, 0$ .
Results. 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 cannot be ruled out with high confidence.
Conclusions. 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 of the power-law cosmology.

Key words: cosmological parameters -- cosmology: theory -- X-rays: galaxies: clusters