AGN III—primordial activity in the nuclei of disk galaxies with pseudobulges

• Published in: Astronomy reports 2013-06, Vol.57 (6), p.401-409
• Main Authors: Komberg, B. V., Ermash, A. A.
• Format: Article
• Language: English
• Subjects: Astronomy; Astrophysics; Black holes; Evolution; Observations and Techniques; Physics; Physics and Astronomy; Quasars; Stars & galaxies
• ISSN: 1063-7729; 1562-6881
• DOI: 10.1134/S1063772913060036

Observational data on the evolution of quasars and galaxies of various morphological types and numerical simulations carried out by various groups are used to argue that low-redshift ( z < 0.5) quasars of types I and II, identified with massive elliptical and spiral galaxies with classical bulges, cannot be undergoing a single, late phase of activity; i.e., their activity cannot be “primordial,” and must have “flared up” at multiple times in the past. This means that their appearance at low z is associated with recurrence of their activity—i.e., with major mergers of gas-rich galaxies (so-called wet major mergers)—since their lifetimes in the active phase do not exceed a few times 10 7 yrs. Only objects we have referred to earlier as AGN III, which are associated with the nuclei of isolated, late-type spiral galaxies with low-mass, rapidly-rotating “pseudobulges,” could represent primordial AGNs at low z . The black holes in such galaxies have masses M BH < 10 7 M ⊙ , and the peculiarities of their nuclear spectra suggest that they may have very high specific rotational angular momenta per unit mass. Type I narrow-line (widths less than 2000 km/s) Seyfert galaxies (NLSyIs) with pseudobulges and black-hole masses M BH < 10 7 M ⊙ may be characteristic representatives of the AGN III population. Since NLSyI galaxies have pseudobulges while Type I broad-line Seyfert galaxies have classical bulges, these two types of galaxies cannot represent different evolutionary stages of a single type of object. It is possible that the precursors of NLSyIs are “Population A” quasars.