Astron. Astrophys. Suppl. Ser. 132, 197-210
Optical colour maps of Seyfert galaxies
Send offprint request: J.K. Kotilainen (Tuorla address)
1 - International School for Advanced Studies (SISSA), via Beirut 2-4, I-34014 Trieste, Italy
2 - Tuorla Observatory, University of Turku, Väisäläntie 20, FIN-21500 Piikkiö, Finland
Received January 30; accepted April 20, 1998
We present optical broad band B-I colour maps of a further sample of 10 Seyfert 2 galaxies. In these bands, the contribution from emission lines to the total flux is small, and hence the images predominantly trace the continuum distribution. As in our earlier colour maps of a sample of Seyferts type 1 and 2, we detect extended blue continuum components in the circumnuclear region of several galaxies. These components are either elongated (in Mkn 533, Mkn 607, Mkn 1066, NGC 5347, NGC 5953 and NGC 7319) or form a double structure across the nucleus (in NGC 5929). They are closely aligned with the radio and emission line axes of these galaxies and probably arise from scattering of nuclear continuum light by extranuclear mirrors. Similar blue elongations (in Mkn 1 and NGC 7212) and double structures (in NGC 788) are less well aligned with the radio and line emission, and their relationship with scattering regions must be considered uncertain. The colours of the blue maxima are consistent with those expected from scattering off dust or electrons, a conclusion strengthened by the combined sample of the two papers in this series. Our findings thus strongly support the current unified models of AGN.
Key words: galaxies: active -- galaxies: nuclei -- galaxies: seyfert -- galaxies: stellar content -- galaxies: structure