Quasar C Iv Emission Lines Of The Baldwin Effect

Baldwin Effect, which is firstly discovered by Baldwin in 1977, is the anti-correlation between the C IV emission line equivalent width (EW) and the continuum luminosity at 1450(?) in QSOs. This correlation was explored in QSOs for other broad emission lines, such as Lyα, SII V1400, O VI 1034, NV 1240, Mg II 2800, Hβ4861; for narrow emission lines, such as [O III] 5007, [O II] 3727, [N v] 3426, [N III]3869; even for the Fe Kαemission line in X-ray spectrum. It is not clear whether the Baldwin Effect is actually driven by a relationship between EW and other fundamental parameters that happen to be correlated with continuum luminosity, such as the redshift, the Eddington ratio, and the supermassive black hole mass.In this thesis, using spectral data from the Sloan Digital Sky Survey Data Release 5, we set up a largest sample of 26623 quasars with redshift 1.5≤z≤5.1 to investigate the C IV Baldwin Effect. We find that there is a strong correlation between C IV emission line equivalent width and the continuum luminosity at 1450(?), which confirms the existence of C IV Baldwin Effect in our sample. By investigating C IV Baldwin Effect in different redshift bins, we find that, up to z～5, the slope of the Baldwin Effect seems to have no effect of cosmological evolution.For a sub-sample of 13960 quasars, we calculate the supermassive black hole masses from C IV line width and the empirical R-L relation and investigate the origin of the Baldwin Effect. We find that C IV EW has a stronger correlation with supermassive black hole mass respect to Eddington ratio. This suggests that the supermassive black hole mass is probably the primary driver for Baldwin Effect.