Origin of the Mg II light-curve complexity

Determine whether the complex variability observed in the OzDES Mg II emission-line light curves is an intrinsic feature of Mg II variability or instead results from data reduction procedures and complications caused by iron contamination.

Background

The hierarchical reverberation-mapping analysis finds that approximately two thirds of the OzDES Mg II sources have no significant structured variability, while many of the remaining structured sources still lack clear reverberation lags. The paper emphasizes that the simple call-and-response light-curve models used for reverberation mapping appear particularly inadequate for this subsample.

Resolving whether the observed complexity is astrophysical or introduced by the data-processing pipeline is important for interpreting the low Mg II reverberating fraction and for improving population-level radius–luminosity constraints. The paper identifies both intrinsic Mg II variability and data-reduction effects, including iron contamination, as possible explanations but does not distinguish between them.