Robust single-epoch C IV mass calibration for high-redshift RCL AGNs

Develop a robust single-epoch virial black hole mass calibration based on the C IV λ1549 emission line for high-redshift recurrent changing-look active galactic nuclei that exhibit variability in C IV, enabling reliable black hole mass estimates.

Background

The authors estimate black hole masses using single-epoch spectra and standard BLR radius–luminosity relations. For most objects, Hβ or Hα lines support established calibrations.

For the one high-redshift source with a variable C IV emission line, the authors state that robust single-epoch mass calibrations are not yet firmly established, indicating the need for improved calibrations (e.g., with corrections for non-virial contributions) to obtain reliable mass estimates.