X-ray luminosity function in the redshift range 3.0 ≤ z ≤ 6.0 for the PDE (top) and LDDE model (bottom). The shaded regions represent the 68% and 95% confidence intervals of the XLF when integrating over 20 ≤ log N_H ≤ 26, while the black lines show the XLF when integrating over 20 ≤ log N_H ≤ 24. The points show the binned luminosity function. For comparison, shown are the XLFs derived by previous X-ray studies in the column density range log N_H = 20 − 24. The best-fitting models of these studies are evaluated at the mean redshift of each bin.