A significant excess in major merger rate for AGNs with the highest Eddington ratios at z<0.2

• Published in: arXiv.org 2020-09
• Main Authors: Marian, V, Jahnke, K, Andika, I, Banados, E, Bennert, V N, Cohen, S, Husemann, B, Kaasinen, M, Koekemoer, A M, Mechtley, M, Onoue, M, Schindler, J T, Schramm, M, Schulze, A, Silverman, J D, Smirnova-Pinchukova, I, van der Wel, A, Villforth, C, Windhorst, R A
• Format: Article
• Language: English
• Subjects: Active galactic nuclei; Color imagery; Galaxies; Morphology; Red shift
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2010.00022

Observational studies are increasingly finding evidence against major mergers being the dominant mechanism responsible for triggering AGN. After studying the connection between major mergers and AGN with the highest Eddington ratios at z=2, we here expand our analysis to z0.3, and 25 mass- and redshift-matched control galaxies. To match the appearance of the two samples, we add synthetic point sources to the inactive comparison galaxies. The combined sample of AGN and inactive galaxies was independently ranked by 19 experts with respect to the degree of morphological distortion. We combine the resulting individual rankings into multiple overall rankings, from which we derive the respective major merger fractions of the two samples. With a best estimate of 0.41 \(\pm\) 0.12 for the AGN host galaxies and 0.08 \(\pm\) 0.06 for the inactive galaxies our results imply that our AGN host galaxies have a significantly higher merger rate, regardless of the observed wavelength or applied methodology. We conclude that although major mergers are an essential mechanism to trigger local high Eddington ratio AGNs at z=50% of this specific AGN subpopulation still remains unclear.