Observational Cosmology And The Cosmic Distance Duality Relation
  We study the validity of cosmic distance duality relation between angular
diameter and luminosity distances. To test this duality relation we use the
latest Union2 Supernovae Type Ia (SNe Ia) data for estimating the luminosity
distance. The estimation of angular diameter distance comes from the samples of
galaxy clusters (real and mock) and FRIIb radio galaxies. We parameterize the
distance duality relation as a function of redshift in six different ways. Our
results rule out some of the parameterizations significantly.
