Mon. Not. R. Astron. Soc., 462, 966-976 (2016/October-2)
The underlying driver for the C IV Baldwin effect in QSOs with 0 < z < 5.
GE X., BIAN W.-H., JIANG X.-L., LIU W.-S. and WANG X.-F.
Abstract (from CDS):
Broad emission lines is a prominent property of type I quasi-stellar objects (QSOs). The origin of the Baldwin effect for C IV λ1549 Å broad emission lines, i.e. the luminosity dependence of the C IV equivalent width (EW), is not clearly established. Using a sample of 87 low-z Palomar-Green (PG) QSOs and 126 high-z QSOs across the widest possible ranges of redshift (0 < z < 5), we consistently calculate Hβ-based single-epoch supermassive black hole (SMBH) mass and the Eddington ratio to investigate the underlying driver of the C IV Baldwin effect. An empirical formula to estimate the host fraction in the continuum luminosity at 5100 Å is presented and used in Hβ-based MBH calculation for low-z PG QSOs. It is found that, for low-z PG QSOs, the Eddington ratio has strong correlations with PC1 and PC2 from the principal component analysis, and C IV EW has a strong correlation with the optical Fe II strength or PC1. Expanding the luminosity range with high-z QSOs, it is found that C IV Baldwin effect exists in our QSOs sample. Using Hβ-based single-epoch SMBH mass for our QSOs sample, it is found that C IV EW has a strong correlation with the Eddington ratio, which is stronger than that with the SMBH mass. It implies that the Eddington ratio seems to be a better underlying parameter than the SMBH mass to drive the C IV Baldwin effect.
© 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society
black hole physics - galaxies: active - quasars: emission lines - quasars: emission lines
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