On the Clustering Bias of Unresolved Gamma-Ray Sources

The Unresolved γ-Ray Background (UGRB) encodes the collective emission of source populations that are too faint to be detected individually, and its cross-correlation with tracers of the large-scale structure has emerged as a powerful tool to characterize those populations. In this work, we analyze the weak-lensing--UGRB cross-correlation using a reference blazar model. By modeling the relation between blazar γ-ray luminosity and host-halo mass, we infer the average linear bias b(z) and host-halo mass M(z) of the unresolved blazar population. We find that the signal is dominated by moderately biased sources, with b 2 at z 1, hosted by halos with M about O(10 13,M). Repeating the analysis with a misaligned-AGN model yields consistent bias values, indicating that the result is determined by the clustering properties of the UGRB rather than by the details of the γ-ray source model.