Color–magnitude diagrams (M_u − M_r)_Group versus (M_r)_Group. The density map shows the host groups of barred AGN (color scale corresponding to the cumulative percentage of objects, as shown in the key). For comparison, the black solid lines enclose 14%, 28%, 42%, 57%, 71%, and 85% of the host groups of unbarred AGN in the control sample. Middle and lower panels show host groups with different ranges of virial masses: M_Virial< 10^13.5M_⊙ and M_Virial> 10^13.5M_⊙, respectively.