High-redshift quasars spectra

The emission lines were characterised both via a quantitative parametrisation of the line profiles and a decomposition of the emission line profiles using multicomponent fitting routines. We provide spectrophotometric properties and line profile measurements for H{beta}+[OIII]4959,5007, as well as SiIV1397+OIV]1402, CIV1549+HeII1640, and the 1900{AA} blend (including AlIII1860, SiIII]1892, and CIII]1909). For six out of the 22 objects, a significantly blueshifted component on the H{beta} profile is present.

In 14 out of 22 cases, an H{beta} outflowing component associated with [OIII] is detected. The majority of [OIII]4959,5007 emission line profiles show blueshifted velocities higher than 250km/s. We find extremely broad [OIII]4959,5007 emission that is comparable to the width of H{beta} broad profile in some highly accreting quasars.

The [OIII]4959,5007 and CIV1549 blueshifts show very high amplitudes and a high degree of correlation. The line widths and shifts are correlated for both [OIII]4959,5007 and CIV1549, suggesting that emission from outflowing gas is providing a substantial broadening effect to both lines. Otherwise, the links between CIV1549 centroid velocity at half intensity (c(1/2)), Eddington ratio (L/L_Edd_), and bolometric luminosity are found to be in agreement with previous studies of high-luminosity quasars.

Our analysis suggests that the behaviour of quasars of very high luminosity all along the main sequence is strongly affected by powerful outflows involving a broad range of spatial scales. The main sequence correlations remain valid at high redshift and high luminosity even if a systematic increase in line width is observed. Scaling laws based on UV AlIII1860 and H{beta} emission lines are equally reliable estimators of M_BH_.