AGNs and Environment: AGN Population and Deficiency of BLAGNs in Compact Groups of Galaxies

To explore the connection between AGN activity and environment in the nearby Universe, we have carried out a spectroscopic study to determine the frequency and nature of the nuclear activity in two well-defined samples of compact groups (CGs) of galaxies: Hickson Compact Groups and Updated Zwicky Catalogue of Compact Groups. We found that a large fraction of the member-galaxies, 63% of the HCG galaxies and 67% of the UZC-CG galaxies, show emission lines. From them, low luminosity AGN is the most frequent activity type found in Compact Groups. Only 8 BLAGNs have been detected, showing a clear deficiency of broad line AGNs that must be related to the compact group environment, where galaxies suffer slow encounters and morphological transformations that result in an important decrease of the total content of gas.