Testing power-law cosmology with galaxy clusters

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, with , 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 α parameter with curvature .

Results. We find that the best fit happens for an open scenario with the power index  ± 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.