Phylogenetic Analyses of Quasars and Galaxies

Abstract

Phylogenetic approaches have proven to be useful in astrophysics. We have recently published a Maximum Parsimony (or cladistics) analysis on two samples of 215 and 85 low-z quasars (z < 0.7) which offer a satisfactory coverage of the Eigenvector 1-derived main sequence. Cladistics is not only able to group sources radiating at higher Eddington ratios, to separate radio-quiet (RQ) and radio-loud (RL) quasars and properly distinguishes core-dominated and lobe-dominated quasars, but it suggests a black hole mass threshold for powerful radio emission as already proposed elsewhere. An interesting interpretation from this work is that the phylogeny of quasars may be represented by the ontogeny of their central black hole, i.e. the increase of the black hole mass. However these exciting results are based on a small sample of low-z quasars, so that the work must be extended. We are here faced with two difficulties. The first one is the current lack of a larger sample with similar observables. The second one is the prohibitive computation time to perform a cladistic analysis on more that about one thousand objects. We show in this paper an experimental strategy on about 1,500 galaxies to get around this difficulty. Even if it not related to the quasar study, it is interesting by itself and opens new pathways to generalize the quasar findings.

Radio loudness along the quasar main sequence

“…Following the E1 trend from the B1 ++ to the A4 ST, there is an increase of Eddington ratio and a decrease of the black hole mass, in agreement with past works (e.g., Fraix-Burnet et al 2017, and references therein). Populations A and B as a whole also show difference in terms of the M BH and Eddington ratios, with Population B showing more massive BH having a lower Eddington ratio with respect to the Population A.…”

“…Classical FRII along with the FRII identified in this work are extended sources, whose ages are estimated around several hundreds of million years (e.g., Ito et al 2006). The lobe extension has an evolutionary meaning akin to M BH that can only grow over cosmic time (Fraix-Burnet et al 2017). So, whether the R K distribution may appear unimodal or bimodal may depend on the M BH distribution of the sample.…”

“…There is no doubt that several physical parameters affect the E1 MS. Recent works (e.g., Sulentic et al 2011;Fraix-Burnet et al 2017) present a list of them and of their relation to observed parameters. The physical interpretation of the MS is still being debated (Shen & Ho 2014;Panda et al 2018), although there is a growing consensus that the main factors shaping the MS occupation in the optical plane R FeII -FWHM(Hβ) (at least for a low-z sample) are the Eddington ratio (λ E ) and the viewing angle defined as the angle between the line-of-sight and the symmetry axis of the active nucleus.…”

“…It is therefore straightforward to think about a physicallymotivated distinction between Population A and Population B. In a word, Population A sources are fast-accreting objects with relatively small black hole masses (at least at low-z) and population B are the ones with high black hole mass and low λ E (e.g., Marconi et al 2009;Fraix-Burnet et al 2017).…”

Absorbed relativistic jets in radio-quiet narrow-line Seyfert 1 galaxies

“…The physical driver of the MS may be a combination of inclination and Eddington ratio (Panda et al 2019). The latter is very high in population A sources like NLS1s (low FWHM and high R4570), and along with the low black hole mass and several other physical properties, this characteristic may indicate that NLS1s and possibly population A sources in general may be one of the early phases of AGN life (Mathur 2000;Sulentic et al 2000;Fraix-Burnet et al 2017;Berton et al 2017Berton et al , 2020.…”