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 clusters samples compiled by De Filippis {\it et al.} and Bonamente {\it et al.}. Two parameterizations for $\eta(z)$, i.e., $\eta(z)=1+\eta_0z$ and $\eta(z)=1+\eta_0z/(1+z)$, are used. We find that the DD relation can be accommodated at $1\sigma$ confidence level (CL) for the De Filippis {\it et al.} sample and at $3\sigma$ CL for the Bonamente {\it et al.} sample. We also examine the DD relation by postulating two more general parameterizations: $\eta(z)=\eta_0+\eta_1z$ and $\eta(z)=\eta_0+\eta_1z/(1+z)$, and find that the DD relation is compatible with the results from the De Filippis {\it et al.} and the Bonamente {\it et al.} samples at $1\sigma$ and $2\sigma$ CLs, respectively. Thus, we conclude that the DD relation is compatible with present observations. 
Zhengxiang Li, Puxun Wu, Hongwei Yu
astro-ph.CO astro-ph.GA gr-qc