a) f_(U)LIRGs for IRGs in L1 as a function of Σ₅. Circle (early-type neighbor case) and square (late-type neighbor case) are median values of each density bin. Vertical dashed line indicates the Σ₅ that roughly corresponds to one virial radius of the clustercentric radius (R ~ r_200,cl) determined from the comparison between Σ₅ and the distance to galaxy clusters in L1. b) Same as above, but for f_(U)LIRGs vs. R / r_200,cl.