Left panel: fraction of X-ray-selected AGN among galaxies with different selection criteria in dense environment for high-z overdensities, as reported in the literature (Lehmer et al. 2009; Digby-North et al. 2010; Lehmer et al. 2013; Krishnan et al. 2017; Macuga et al. 2019; Vito et al. 2020; Polletta et al. 2021; Tozzi et al. 2022; Vito et al. 2024; Travascio et al. 2025). Right panel: X-ray luminosity limit vs. AGN fraction in dense environments for high-redshift overdensities. Our measurements are shown as red diamonds. A filled diamond represents the fraction of AGN directly detected among the LAEs, and an empty diamond refers to the unresolved AGN fraction inferred from the stacking analysis at the 90% confidence level. The colors of the points in the graph indicate the different selection criteria: red for LAEs, green for Hα-emitting galaxies (HEAs), and blue for submillimeter-selected dusty star-forming galaxies (DSFGs). The f_AGN^* of MQN01 is calculated including M_* > 10^10.5 M_⊙ galaxies (Travascio et al. 2025).