Program: GS-2018B-Q-134

The so-called transitional or composite galaxies are objects that sit in a transition locus between star-forming (SF) galaxies and active galactic nuclei (AGN) in the BPT diagnostic diagrams. These have historically been explained as having a mix of SF and AGN activity in their centers. However, up to now, there is no clear detailed understanding of how these two processes are spatially distributed in the galaxies and how they are linked with each other. A couple of years ago an important step was made towards understanding the ionization mechanism that is dominant in some of these systems when Rich et al. (2015) obtained IFU spectroscopy of 27 ULIRGS (generally mergers and interacting galaxies that populate the transitional region in the BPT diagram) and showed that surprisingly the main ionization radiation in these galaxies are shocks and star formation. Given the importance of this result we want to do a very similar study for three other galaxies (non ULIRGS), in a different environment (the dense environment of compact groups), and with better spatial resolution (given that our galaxies are in the very nearby universe), to see how ubiquitous this result is. Here we propose to use GMOS/IFU datacubes to determine if shocks and/or AGN and/or star formation are taking place in two galaxies located in a compact group. This proposal plans to complete the observations of the program GS-2016B-Q-63 which were not taken due to weather conditions. Using line-maps and diagnostic diagrams we will be able to determine the real nature of these systems, and to determine if the environment plays a role in the nuclear activity of these galaxies.