Open AccessMultiwavelength study of the nuclei of a volume‐limited sample of galaxies – II. Optical, infrared and radio observations
Author(s) -
Lira P.,
Johnson R. A.,
Lawrence A.,
Cid Fernandes R.
Publication year - 2007
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2007.12006.x
Subject(s) - physics , astrophysics , galaxy , active galactic nucleus , luminous infrared galaxy , luminosity , radio galaxy , luminosity function , infrared , star formation , astronomy , spectroscopy
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 M B ∼−12 to −22 range.