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ABSTRACT We present a comprehensive analysis of the X-ray spectral properties of 198 newly identified active galactic nuclei (AGNs), leveraging archival data from the Chandra X-ray Observatory. All these AGNs exhibit a power-law spectral signature spanning a broad energy range of 0. 5\!-\!7. 0 keV, characterized by the photon index () values ranging from 0. 3^+0. 16-₀. ₁₄ to 2. 54^+0. 14-₀. ₁₃. Particularly, 76 of these AGNs display discernible levels of intrinsic absorption, after considering the Galactic absorption. The column densities associated with this local absorption (n ₇^ local) are within a range of 10^19\!-\!10^22\ cm^{-2}. We study the cosmological evolution of AGNs using the variation of n ₇^ local and with their estimated redshift. The intrinsic spectral signature did not reveal any significant cosmological evolution; however, a deficit of hard sources at high redshift is possibly intrinsic. Our sample covers several orders of broad-band intrinsic luminosity (L ₁^ intr) ranging from 4. 59^+0. 41-₀. ₄₁ 10^42 to 2. 4^+0. 12-₀. ₁₂ 10^46\, erg~s^-1 with peak at 1. 84 redshift. We also investigate the hardness–luminosity diagram to further probe the AGNs. We conduct a sanity check by applying our findings to known AGNs, and the results are consistent with our observations.
Ghosh et al. (Wed,) studied this question.