English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The connection between multifrequency quasar observational and physicalparameters related to accretion processes is still open to debate. In the last20 year, Eigenvector 1-based approaches developed since the early papers byBoroson and Green (1992) and Sulentic et al. (2000b) have been proven to be aremarkably powerful tool to investigate this issue, and have led to thedefinition of a quasar "main sequence". In this paper we perform a cladisticanalysis on two samples of 215 and 85 low-z quasars (z 0.7) which were studiedin several previous works and which offer a satisfactory coverage of theEigenvector 1-derived main sequence. The data encompass accurate measurementsof observational parameters which represent key aspects associated with thestructural diversity of quasars. Cladistics is able to group sources radiatingat higher Eddington ratios, as well as to separate radio-quiet (RQ) andradio-loud (RL) quasars. The analysis suggests a black hole mass threshold forpowerful radio emission and also properly distinguishes core-dominated andlobe-dominated quasars, in accordance with the basic tenet of RL unificationschemes. Considering that black hole mass provides a sort of "arrow of time" ofnuclear activity, a phylogenetic interpretation becomes possible if cladistictrees are rooted on black hole mass: the ontogeny of black holes is representedby their monotonic increase in mass. More massive radio-quiet Population Bsources at low-z become a more evolved counterpart of Population A i.e., winddominated sources to which the "local" Narrow-Line Seyfert 1s belong.

The phylogeny of quasars and the ontogeny of their central black holes