Long slit spectroscopy of emission line galaxies. I. The sample.

Abstract

We present optical long slit spectroscopy for a sample of fifteen emission line galaxies with nuclei showing a sequence of activity levels in the radio, X-ray and/or optical ranges. They are presented in order of increasing activity in the optical range: LINERs, Seyfert 2s, obscured Seyfert 1s and Seyfert 1s. The existence of extended ionized envelopes is reported here for the first time for about half the galaxies in our sample, including two unusual nebulosities of low ionization level around the Seyfert type 1 nuclei A0945-30 and MCG-2-58-22. The diameters of the observed ionized envelopes range from a couple of kiloparsecs to several tens of kiloparsecs. For several objects, in particular LlNERs, good optical spectra covering a large wavelength range were previously available neither for the nuclei nor for the outer regions. We describe the main properties of each galaxy at different wavelengths, and give observed line intensities for the nuclei and for several extranuclear regions, totalizing 72 different zones. We discuss the reddening correction to be applied in each case and derive physical parameters such as the electronic temperature and density whenever possible. The velocity fields of the ionized gas are also described. In a forthcoming paper, we will study the characteristics and nature of the ionizing source, using photoionization models. We will derive the gas density (thus the filling factor) and the heavy element abundances. We will also search for correlations between the morphology of the ionized gas, the properties of the active nucleus and the presence of a companion galaxy.