We investigate the conjecture by Sikora, Stawarz & Lasota (2007) that the observed AGN–radioloudness bimodality can be explained by the morphology related bimodality of black-hole spin distribution in the centers of galaxies: central black holes in giant elliptical galaxies may have (on average) much larger spins than black holes in spiral/disc galaxies. We study how accretion from a warped dis...

Astronomers knew early in the twentieth century that some galaxies have emissionline nuclei. However, even the systematic study by Seyfert (1943) was not enough to launch active galactic nuclei (AGN) as a major topic of astronomy. The advances in radio astronomy in the 1950s revealed a new universe of energetic phenomena, and inevitably led to the discovery of quasars. These discoveries demande...

The connection between normal and active galaxies is reviewed, by summarizing our progress on answering nine key questions. (1) Do all galaxies contain massive dark objects (MDOs)? (2) Are these MDOs actually supermassive black holes? (3) Why are the dark objects so dark? (4) Do all galaxies contain an Active Galactic Nucleus (AGN)? (5) Are the “dwarf AGN ” really AGN? (6) Does AGN activity cor...

It is still a matter of debate whether the properties of galaxies hosting an Active Galactic Nucleus (AGN) are different from the properties of quiescent galaxies. We constructed a sample of ∼ 50 AGN at a mean redshift of z ≈ 0.6 that lack a detectable optical nucleus. This characteristic allows to study the properties of the host galaxies with much higher accuracy than in the case of " normal ...

Sanders et al. (1988) proposed an evolutionary connection between Ultraluminous Infrared Galaxies (ULIGs) and optically-selected QSOs. In this scenario, mergers of dust and gas-rich galaxies provide the fuel to create and/or fuel an AGN and circumnuclear starburst. This dust completely enshrouds the AGN, and subsequent reradiation of the shortwavelength AGN emission produces the high far-IR lum...

The analysis of a sample of 30 isolated spiral galaxies with and without an AGN results in active and control galaxies having similar bulge and disk properties (since both samples are selected to match in morphological and bar classification, they have similar bar percentages). Secondary bars seem also to be indistinguishable. The central kinematics (both stellar and gas) are also studied in or...

A significant fraction of extended radio sources presents a peculiar X-shaped radio morphology: in addition to the classical double lobed structure, radio emission is also observed along a second axis of symmetry in the form of diffuse wings or tails. We reexamine the origin of these extensions relating the radio morphology to the properties of their host galaxies. The orientation of the wings ...

Observations with the Wide-Field/Planetary Camera-2 of the Hubble Space T elescope are presented for three radio-loud quasars : 3C 48 (z\ 0.367), B2 1425]267 (z\ 0.366), and 3C 345 (z\ 0.594). All three quasars have luminous (D4 ] L*) galaxies as hosts, which are either elliptical (B2 1425]267 and 3C345) or interacting (3C 48), and all hosts are 0.5È1.0 mag bluer in V [I than other galaxies wit...

The connection between normal and active galaxies is reviewed, by summarizing our progress on answering nine key questions. (1) Do all galaxies contain massive dark objects (MDOs)? (2) Are these MDOs actually supermassive black holes? (3) Why are the dark objects so dark? (4) Do all galaxies contain an Active Galactic Nucleus (AGN)? (5) Are the " dwarf AGN " really AGN? (6) Does AGN activity co...