The evolution of the heaviest supermassive black holes in jetted AGNs

We present the space density evolution, from z = 1.5 up to z = 5.5, of the most massive (M >= 109 M-circle dot) black holes hosted in jetted active galactic nuclei (AGNs). The analysis is based on a sample of 380 luminosity-selected (lambda L-1350 >= 10(46) erg s(-1) and P-5GHz >= 10(27) W Hz-1) flat spectrum radio quasars (FSRQs) obtained from the Cosmic Lens All Sky Survey (CLASS). These sources are known to be face-on jetted AGNs (i.e. blazars) and can be exploited to infer the abundance of all the (misaligned) jetted AGNs, using a geometrical argument. We then compare the space density of the most massive supermassive black holes hosted in jetted AGNs with those present in the total population (mostly composed by non-jetted AGNs). We find that the space density has a peak at z similar to 3, which is significantly larger than the value observed in the total AGN population with similar optical/UV luminosities (z similar to 2.2), but not as extreme as the value previously inferred from X-ray-selected blazars (z similar to 4). The jetted fraction (jetted AGNs/total AGNs) is overall consistent with the estimates in the local Universe (10-20 per cent) and at high redshift, assuming Lorentz bulk factors Gamma approximate to 5. Finally, we find a marginal decrease in the jetted fraction at high redshifts (by a factor of similar to 2). All these evidences point towards a different evolutionary path in the jetted AGNs compared to the total AGN population.

Automated summary

This study presents the evolution of space density for the most massive black holes hosted in jetted active galactic nuclei (AGNs) from z = 1.5 to z = 5.5. The findings show a peak in space density at z ~ 3, which is higher than that observed in the total AGN population. The study also highlights a slight decrease in the ratio of jetted AGNs to total AGNs at high redshifts.