NIR SED of blue quasars

We produced average spectral energy distributions (SED) in different bins of the $z-L_bol_ parameter space to estimate how the NIR SED evolves according to these parameters. We find that the NIR luminosity decreases for increasing L_bol_ at any redshift. At the same time, the shape of the NIR SED in our sample is consistent with a non-evolution with z.

As a consequence, all the explored proxies for the CF exhibit significant anti-correlations with L_bol_, but not with z. Additionally, the CF also shows a shallower anti-correlation with the Eddington ratio (lambda_Edd_), yet the current systematic uncertainties, as well as the limited dynamical range, do not allow us to precisely constrain the role of the Eddington ratio. Lastly, we derived the covering factor from the ratio between the NIR and optical luminosity and we employed it to set a lower limit for the X-ray obscuration at different redshifts.