The Baldwin effect in complete optically selected samples of quasars

From an analysis of the equivalent widths of the C IV and Mg II lines in the largest available data set of unbiased, complete samples of optically selected quasars, it is found that the least-squares fit of the equivalent width versus absolute magnitude gives the following relations : EW(C IV) ∞ L(1550) −0.13 and EW(Mg II) ∞ L(2798) −0.08 . For both lines the slope of the correlation between the equivalent widths and the luminosities is very shallow. In particular, the slope for the C IV line is significantly different from the previous «canonical» value for the slope of the «Baldwin effect» in quasars