Relationship between the Detection Rates of Mg <scp>II</scp> Absorption Lines and [O <scp>III</scp>] Emission Line Asymmetries

Abstract 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 DR12Q exhibiting prominent [O iii ] emission lines, of which 351 quasars have Category 1 Mg ii absorption lines (4365 ≤ υ r ≤ 10,000 km s −1 ) and 518 quasars have Category 2 Mg ii absorption lines (610 ≤ υ r ≤ 4365 km s −1 ). 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) show 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) increase with rising δv . Finally, we discuss the results from two perspectives: quasar evolutionary stages and acceleration mechanisms driven by radiation pressure.