Unified Scheme for Seyferts or the Influence of Interactions?

Abstract

The first statistical study of the environment of Seyfert galaxies (of both types 1 and 2) was done by Petrosian (1982), who found that Sy2 galaxies had an excess of nearby companion galaxies with respect to field galaxies. Dahari (1985) made a similar study, and obtained that both types of Seyfert galaxies are found five times more often in interacting systems that “normal” galaxies. Fuentes-Williams & Stocke (1988) obtained the opposite result: that Seyfert galaxies have no significative excess of nearby companions, and MacKenty (1989) obtained the same result as Petrosian. The last papers appeared in 1995: Rafanelli, Violato & B.aruffolo (1995) obtained a similar result as Dahari. Laurikainen & Salo (1995) made a careful attempt to understand the discrepancies; they concluded that the incompatibilities in the results were mainly due to control sample selection, and problems in background galaxy determination. Their work confirmed the result of the first study. However, in order to explain the discrepancies between previous results, they also used incorrectly defined control samples. Objections can be made against all of these works for this only reason. We have repeated the study using, for the first time, the digitized Palomar Sky Survey plates (paSS), an automated selection procedure, and correctly defined control samples (Osterbrock 1993).

Searching for the physical drivers of eigenvector 1: influence of black hole mass and Eddington ratio

“…Boroson, Persson & Oke 1985;Boroson & Green 1992;Murray et al 1995;Nicastro 2000;Marziani et al 2001;Boroson 2002); (2) outflow/wind properties that are expected to depend on Eddington ratio (e.g. Dultzin-Hacyan, Marziani & Sulentic 2000;Marziani et al 2001); (3) orientation effects that will blur any physical correlation and displace sources in the direction of increasing Eddington ratio ; see also , Nagao, Taniguchi & Murayama 2000;Zhou et al 2003); (4) broad-line region (BLR) structural effects (Sulentic et al 2000b; see also Gaskell et al 1999); and (5) last, but not least, evolutionary effects that will lead to an increase of black hole mass as well as of the [O III] λ5007 rest-frame equivalent width Boroson 2002). We will briefly discuss them in Sections 8.4 and 9.…”