Multiwavelength study of the nuclei of a volume-limited sample of galaxies - II. Optical, infrared and radio observations
Abstract
We present optical and infrared broad-band images, radio maps, and optical spectroscopy for the nuclear region of a sample of nearby galaxies. The galaxies have been drawn from a complete volume-limited sample for which we have already presented X-ray imaging. We modelled the stellar component of the spectroscopic observations to determine the star formation history of our targets. Diagnostic diagrams were used to classify the emission-line spectra and determine the ionizing mechanism driving the nuclear regions. All those sources classified as active galactic nuclei present small Eddington ratios (~10-3 -10-6), implying a very slow growth rate of their black holes. We finally investigate the relative numbers of active and normal nuclei as a function of host galaxy luminosity and find that the fraction of active galaxies slowly rises as a function of host absolute magnitude in the MB ~ -12 to -22 range.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- December 2007
- DOI:
- 10.1111/j.1365-2966.2007.12006.x
- Bibcode:
- 2007MNRAS.382.1552L
- Keywords:
-
- galaxies: active;
- galaxies: general;
- galaxies: nuclei