Histograms showing the X-ray luminosity (left) and redshift (right) distribution. Blue histograms shows the NORAS-REFLEX sample, red the relic cluster sample. The solid blue line displays the predicted luminosity/redshift distributions from Nuza et al. (2011) for clusters with fluxes  >3.0  ×  10^-12 erg s^-1 cm^-2 , while the solid red line is the prediction for clusters hosting relics in the simulation. The fraction of clusters with relics is given by the black solid line (the ratio of the blue and red lines).