SIMBAD references

We present the single-epoch black hole mass estimators based on the C IV λ1549 broad emission line, using the updated sample of the reverberation-mapped active galactic nuclei and high-quality UV spectra. By performing multi-component spectral fitting analysis, we measure the C IV line widths (FWHM_ C IV_and line dispersion, σ_ C IV_) and the continuum luminosity at 1350 Å (L ₁₃₅₀) to calibrate the C-IV-based mass estimators. By comparing with the Hβ reverberation-based masses, we provide new mass estimators with the best-fit relationships, i.e., M_BH ∝L₁₃₅₀^0.50±0.07 σ_CIV² and M_BH ∝L₁₃₅₀^0.52±0.09 FWHM_CIV^0.56±0.48. The new C-IV-based mass estimators show significant mass-dependent systematic difference compared to the estimators commonly used in the literature. Using the published Sloan Digital Sky Survey QSO catalog, we show that the black hole mass of high-redshift QSOs decreases on average by ∼0.25 dex if our recipe is adopted.