Relationship between the detection rate of Mg II absorption lines and [O III] emission line asymmetry

This study investigates the relationship between the detection rates of Mg II absorption lines and the asymmetries of [O III] emission lines. We first select 21,364 quasars from the Sloan Digital Sky Survey (SDSS) DR12Q exhibiting prominent [O III] emission lines, of which 351 quasars have Category 1 Mg II absorption lines (4365 ≤ v_r ≤ 10000 km/s) and 518 quasars have Category 2 Mg II absorption lines (610 ≤ v_r v 4365 km/s). Subsequently, we quantify the asymmetries of [O III] emission lines using the velocity offset δv, and find that the detection rates of Category 1 Mg II absorption lines (predominantly intervening absorbers) shows no correlation with the blueshifted asymmetries of [O III] emission lines, whereas the detection rates of Category 2 Mg II absorption lines (primarily outflow and intervening absorbers) increases with rising δv. Finally, we discuss the results from two perspectives: quasar evolutionary stages and acceleration mechanisms driven by radiation pressure.