Line and continuum variability of two intermediate-redshift, high-luminosity quasars

Abstract

Context.It has been shown that the luminosity of active galactic nuclei and the size of their broad line region obey a simple relation of the type , from faint Seyfert nuclei to bright quasars, allowing single-epoch determination of the central black hole mass from their luminosity L and width of H emission line. Adopting this mass determination for cosmological studies requires the extrapolation to high redshift and luminosity of a relation whose calibration relies so far on reverberation mapping measurements performed for L 1046 erg s-1 and redshift z 0.4.