THE EFFECTS OF THE LOCAL ENVIRONMENT ON ACTIVE GALACTIC NUCLEI

摘要: There continues to be significant controversy regarding the mechanism(s) responsible for initiation and maintenance of activity in galactic nuclei. In this paper we will investigate possible environmental triggers nuclear through a statistical analysis large sample galaxy groups. The focus is identify active nuclei (AGNs) other emission-line galaxies these groups compare their frequency with over 260,000 isolated from same catalog. are taken catalog Yang et al., which 20,000 virialized (2 ≤ N 20) redshifts between 0.01 0.20 Sloan Digital Sky Survey. We first completeness our data set find, though biases concern particularly at higher redshift, that provide fair representation local universe. After correcting equivalent widths extinction underlying Balmer stellar absorption, classify using traditional ratios, while incorporating measurement uncertainties. find significantly fraction AGNs compared sample. Likewise, absorption-line found groups, star-forming prefer environments. Within grouped environments, more frequently small- medium-richness larger richnesses. Groups containing only have smaller virial radii, velocity dispersions, masses those galaxies. Furthermore, AGN increases decreasing distance group centroid, independent morphology. Using properties obtained Galaxy Zoo, there an increased within merging systems, unlike These results some indication environment does play role initiating nuclei, but it by no means simple or straightforward.