Hard X-ray bolometric correction as a function of redshift. In the top panel, the normalized bolometric correction has been obtained by dividing K_X for the corresponding bolometric correction given by Eq. (2). Bottom panel: K_X as a function of redshift in five ranges of hard X-ray luminosity. Black hexagons are the average values of K_X computed in bins of redshift and the dashed line is the average K_X of the whole sample within the entire redshift range. Symbols are the same as in Fig. 6.