A test for cosmic distance duality
  Testing the cosmic distance duality relation (CDDR) constitutes an important task for cosmology and fundamental physics since any violation of it would be a clear evidence of new physics. In this {\it Letter}, we propose a new test for the CDDR using only measurements of the gas mass fraction of galaxy clusters from Sunyaev-Zeldovich ($f_{SZE}$) and X-ray surface brightness ($f_{X-ray}$) observations. We show that the relation between current $f_{X-ray}$ and $f_{SZE}$ observations is given by $f_{SZE}=\eta f_{X-ray}$, where $\eta$ quantifies deviations from the CDDR. Since this latter expression is valid for the same object in a given galaxy cluster sample, the method proposed removes possible contaminations from different systematics error sources and redshift differences involved in luminosity and angular diameter distance measurements. We apply this cosmological model-independent methodology to the most recent $f_{X-ray}$ and $f_{SZE}$ data and show that no significant violation of the CDDR is found. 
R. F. L. Holanda, R. S. Goncalves, J. S. Alcaniz
astro-ph.CO gr-qc hep-ph