Phylogenetic Analyses of Quasars and Galaxi

Abstract

We have performed a cladistic analysis on two samples of 215 and 85 low-z quasars (z < 0.7) which were studied in several previous works and which offer a satisfactory coverage of the Eigenvector 1-derived main sequence. The data encompass accurate measurements of observational parameters which represent key aspects associated with the structural diversity of quasars. Cladistics is able to group sources radiating at higher Eddington ratios, as well as to separate radio-quiet (RQ) and radio-loud (RL) quasars. The analysis suggests a black hole mass threshold for powerful radio emission and also properly distinguishes core-dominated and lobe-dominated quasars, in accordance with the basic tenet of RL unification schemes. Considering that black hole mass provides a sort of ``arrow of time'' of nuclear activity, our result suggests that the ontogeny of black holes is represented by their monotonic increase in mass. More massive radio-quiet Population B sources at low-z become a more evolved counterpart of Population A i.e., wind dominated sources to which the ``local'' Narrow-Line Seyfert 1s belong. In addition to the analysis of luminous type 1 AGN and low-z quasars, we have applied cladistic techniques to a sample of viz. 4000 galaxies of the WINGS survey which are mostly quiescent or host modest star formation activity and low-luminosity AGNs. Preliminary results are given in this poster.