Multicolor photometry of ten Seyfert 1 galaxies

¹ IATE, Observatorio Astronómico, Universidad Nacional de Córdoba, Laprida 854, 5000, Córdoba, Argentina
² Departamento de Astronomia – UFRGS. Av. Bento Gonçalves 9500, CEP 91501-970, Porto Alegre, RS, Brazil
³ Instituto Astronômico e Geofísico – Universidade de São Paulo, Av. Miguel Stefano 4200, CEP 04301-904, São Paulo, SP, Brazil

Corresponding author: C. J. Donzelli, charly@oac.uncor.edu

Received: 6 September 2001
Accepted: 7 December 2001

Abstract

We present new valuable BVI photometry of ten Seyfert 1 galaxies and narrow band Hα images for six of these objects. The results indicate that the distribution of the luminosity of the sample has an amplitude of almost 4 mag with an average of M_B=-20.7. The observed morphologies are confined to early type galaxies. A barred structure is found in only 2 objects. Despite that early morphological types are dominant in this sample, integrated () colors are very blue. For instance, the SO galaxies show, on average, a . This effect seems to be caused by the luminosity contribution of the active nucleus and/or the disk to the total luminosity of the galaxy. In the B band, the contribution of the active galactic nucleus to the total luminosity of the galaxy varies from 3% to almost 60% and the bulge to disk luminosity ratio () ranges from 0.6 to 22. Signs of tidal interactions seem to be a common characteristic since they are observed in 6 of the objects and one of them seems to be located in a poor cluster not yet identified in the literature. In contrast, Hα extended emission is rare, with only 1 galaxy showing clear evidence of it. Luminosity profile decomposition shows that the model Gauss + bulge + disk properly reproduces the surface brightness of the galaxies. However, in order to account for the luminosity profile, most of the disk galaxies need the inner truncated exponential form with a central cutoff radius ranging from 3 to 10 kpc. This is interpreted in terms of reddened regions that are well identified in the color maps. These regions present very similar colors among them, with . This fact could be associated with the presence of dust confined in the inner regions of the galaxies.