COSMOLOGICAL-MODEL-INDEPENDENT TESTS FOR THE DISTANCE-DUALITY RELATION FROM GALAXY CLUSTERS AND TYPE Ia SUPERNOVA

We perform a cosmological-model-independent test for the distance-duality ((DD) relation eta(z) = D-L(z) (1 + z)(-2)/D-A(z), where D-L and D-A are the luminosity distance and angular diameter distance, respectively, with a combination of observational data for D-L taken from the latest Union2 SNe Ia and that for D-A provided by two galaxy cluster samples compiled by De Filippis et al. and Bonamente et al. Two parameterizations for eta(z), i.e., eta(z) = 1 + eta(0)z and eta(z) = 1 + eta(0)z/(1 + z), are used. We find that the DD relation can be accommodated at 1 sigma confidence level (CL) for the De Filippis et al. sample and at 3 sigma CL for the Bonamente et al. sample. We also examine the DD relation by postulating two more general parameterizations: eta(z) = eta(0) + eta(1)z and eta(z) = eta(0) + eta(1)z/(1 + z), and find that the DD relation is compatible with the results from the De Filippis et al. and the Bonamente et al. samples at 1 sigma and 2 sigma CLs, respectively. Thus, we conclude that the DD relation is compatible with present observations.