Interacting galaxies: effects in the stellar population and the physical properties of the ionized gas

Abstract

There is plenty evidence that galaxy interactions play an important role in enhancing both star formation and nuclear activity in those galaxies. However, there is still no clear agreement in the literature about the correlation between such interactions and the affected physical properties. Gas motions created by the interaction are likely to significantly alter the chemical state of the involved galaxies and modify the usually smooth radial metallicity gradient often found in isolated disc galaxies. Recent evidence for this hypothesis was found in an observational study of the galaxy pair AM 2306-721 (Krabbe et al. 2008), where the O/H abundance estimated in the disc galaxy presented a defined radial gradient, whereas the companion galaxy showed oxygen abundance relatively homogeneous across the disc. In this project we propose to perform a study about the effects of the interaction on the nuclear activity, star formation, stellar population characteristics, in the velocity field and in the distribution of O/H of a sample of galaxies in interaction. The sample have been selected mainly from the morphological class I of the Arp & Madore (1987) catalogue (interacting spirals with small companions). For this project we have long slit spectroscopic data in the range of 3600 a 7300 Å, obtained with the GMOS spectrograph attached to the 8 m telescope South Gemini. The sample comprises 8 interacting galaxies, as well as 14 galaxy systems apparently in interaction; for which there is no information so far about their radial velocities. (AU)