Issue |
Astron. Astrophys. Suppl. Ser.
Volume 121, Number 1, January 1997
|
|
---|---|---|
Page(s) | 77 - 94 | |
DOI | https://doi.org/10.1051/aas:1997115 | |
Published online | 15 January 1997 |
Optical colour maps of Seyfert galaxies
1
Tuorla Observatory, University of Turku, Väisäläntie 20, FIN–21500 Piikkiö, Finland
2
International School for Advanced Studies (ISAS/SISSA), via Beirut 2-4, I-34014 Trieste, Italy e-mail: jkotilai@sissa.it
3
Astrophysics, Nuclear Physics Building, Keble Road, Oxford OX1 3RH, UK e-mail: m.ward1@physics.oxford.ac.uk
Send offprint request to: J.K. Kotilainen (SISSA address)
Received:
24
January
1996
Accepted:
20
May
1996
We present optical broad band colour maps of nine Seyfert
galaxies. In the bands used, the contribution from emission
lines to the total flux is relatively small, and hence the
images predominantly trace the continuum distribution. The
ratios of these images are sensitive to gradients in the stellar
populations, and to reddening by dust. We detect ringlike,
clumpy or elongated morphological features in several galaxies,
which are blue in the index (
for NGC 7469). For
NGC 7469 there is good spatial agreement with the molecular
millimeter CO and radio continuum structure indicating the
presence of star forming regions around its Seyfert nucleus. The
blue elongations and/or double structures seen in the colour
maps of NGC 1068, NGC 3227, NGC 4151, Mrk 3 and Mrk 573 are
roughly parallel to their extended radio and NLR emission and
probably arise from scattering of nuclear light by extranuclear
“mirrors”. In Mrk 78 and Mrk 348, the structure is not well
resolved, possibly because the scattering mirrors are either
less efficient and/or further away from the nucleus than in the
previous galaxies. In NGC 1667, we detect double red maxima,
again possibly related to obscuring material. The colours of the
blue maxima are not well determined due to contamination from
the underlying bulge, but they are generally consistent with
those expected from scattering off dust or electrons. Our
findings thus give further support to the current unified models
of AGN.
Key words: galaxies: nuclei / galaxies: Seyfert / galaxies: stellar content / galaxies: structure / galaxies: photometry
© European Southern Observatory (ESO), 1997