Anti-correlations Between Continuum and Absorption Line Variations in Broad Absorption Line Quasars: Evidence for Ionization-Driven Variability

As one of the pieces of evidence for ionization-driven BAL variation, anti-correlations between the fractional variations of the continuum and absorption line have been observed for several samples of BAL (Lu et al. 2018; Lu & Lin 2018; Vivek 2019). However, these previous studies have not compared the EW variations of BALs at different ionization states with their fractional variations of the continuum.