AGN spiral galaxies in groups: effects of bars (original) (raw)

The impact of bars and interactions on optically selected AGNs in spiral galaxies

Astronomy & Astrophysics, 2018

Aims. With the aim of performing a suitable comparison of the internal process of galactic bars with respect to the external effect of interactions on driving gas toward the inner most region of the galaxies, we explored and compared the efficiency of both mechanisms on central nuclear activity in optically selected active galactic nuclei (AGNs) in spiral galaxies. Methods. We selected homogeneous samples of barred AGNs and active objects residing in pair systems, derived from the Sloan Digital Sky Survey (SDSS). In order to carry out a reliable comparison of both samples (AGNs in barred hosts in isolation and in galaxy pairs), we selected spiral AGN galaxies with similar distributions of redshift, magnitude, stellar mass, color and stellar age population from both catalogs. With the goal of providing an appropriate quantification of the influence of strong bars and interactions on nuclear activity, we also constructed a suitable control sample of unbarred spiral AGNs without a comp...

The Evolution of AGN Activity in Brightest Cluster Galaxies

The Astronomical Journal, 2022

We present the results of an analysis of Wide-field Infrared Survey Explorer (WISE) observations of the full 2500 deg2 South Pole Telescope (SPT)-Sunyaev–Zel’dovich cluster sample. We describe a process for identifying active galactic nuclei (AGN) in brightest cluster galaxies (BCGs) based on WISE mid-IR color and redshift. Applying this technique to the BCGs of the SPT-SZ sample, we calculate the AGN-hosting BCG fraction, which is defined as the fraction of BCGs hosting bright central AGNs over all possible BCGs. Assuming an evolving single-burst stellar population model, we find statistically significant evidence (>99.9%) for a mid-IR excess at high redshift compared to low redshift, suggesting that the fraction of AGN-hosting BCGs increases with redshift over the range of 0 < z < 1.3. The best-fit redshift trend of the AGN-hosting BCG fraction has the form (1 + z)4.1±1.0. These results are consistent with previous studies in galaxy clusters as well as as in field galaxie...