Abstract

Poster - Splinter General   (MW-1801 / virtual plenum)

The fraction of AGNs detected in clusters from deep and wide-field X-Ray surveys

E. Koulouridis, A. Menis, E. Drigga
Institute for Astronomy & Astrophysics, Space Applications & Remote Sensing, National Observatory of Athens GR-15236, Palaia Penteli, Greece, Université Paris-Saclay, Université Paris Cité, CEA, CNRS, AIM, 91191, Gif-sur-Yvette, France, Universitäts-Sternwarte, Fakultät für Physik, Ludwig-Maximilians-Universität München, Scheinerstr. 1, D-81679 München, Germany, Sector of Astrophysics, Astronomy & Mechanics, Department of Physics, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece

AGNs in galaxy clusters experience physical processes that differ from those affecting AGNs in the field, indicating that their activity is strongly influenced by the surrounding environment. However, the dominant mechanisms that trigger and regulate AGN activity in clusters remain uncertain. We investigate factors that may affect the prevalence of AGNs in galaxy clusters, including redshift, distance from the cluster center, and cluster mass. Our analysis is based on a sample of X-ray selected galaxy clusters from the XCLASS survey and clusters from the eROSITA survey. In addition, we use data from the WHL12 cluster catalog and the SDSS DR8 to derive normalized galaxy density profiles in radial bins from the cluster center. We find that the X-ray AGN fraction is consistent with the field in the cluster outskirts but significantly lower in cluster centres, in agreement with previous studies. Our results with the eROSITA sample show no significant dependence of AGN fraction on cluster mass within the explored mass range at the 1σ confidence level. For the XCLASS sample, systematic effects and non-uniform data quality limit the statistical significance of some measurements, although the general trend of suppressed AGN activity in cluster centres is still observed. Overall, our results suggest that the mechanisms triggering AGN activity may differ between cluster centres and outskirts. The surplus of X-ray AGNs identified in the outskirts of relaxed clusters may be attributed to an increased frequency of galaxy mergers and interactions. Our findings suggest that AGN activity does not strongly depend on cluster mass but may evolve with cluster redshift. There is a slight rising AGN fraction toward higher redshifts, likely reflecting the higher availability of cold gas and more frequent galaxy interactions in earlier cosmic epochs.