Neutral hydrogen column density (N_H) as a function of hardness ratio (HR) for the X-ray detected DOGs. The blue region (with N_H > 10²⁴ cm⁻²) represents the Compton-thick (CT) population, while the orange one shows the location of heavily obscured sources with N_H ∼ 5 × 10²³ cm⁻² and the green region situated right below corresponds to the moderately obscured sources, with N_H(cm⁻²) > 10²². The dashed lines show the expected relation between N_H and HR for sources at z = 1, 2, 3, and 4 assuming an intrinsic power law plus photoelectric absorption (red lines) and the MYTorus models (blue lines). The black solid segments show the location for the sources in Table 2 considering the observed HR and their uncertainties and assuming the simple power-law model.