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Changing Ionization Conditions in SDSS Galaxies with AGN as a Function of Environment from Pairs to Clusters

Khabiboulline, Emil T. and Steinhardt, Charles L. and Silverman, John D. and Ellison, Sara L. and Mendel, J. Trevor and Patton, David R. (2014) Changing Ionization Conditions in SDSS Galaxies with AGN as a Function of Environment from Pairs to Clusters. . (Submitted)

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We study how AGN activity changes across environments from galaxy pairs to clusters using 143 843 galaxies with z < 0.2 from the Sloan Digital Sky Survey (SDSS). Using a refined technique, we apply a continuous measure of AGN activity, characteristic of the ionization state of the narrow-line emitting gas. Changes in key emission-line ratios ([NII]λ6548/Hɑ, [OIII]λ5007/Hβ) between different samples allow us to disentangle different environmental effects while removing contamination. We confirm that galaxy interactions enhance AGN activity. However, conditions in the central regions of clusters are inhospitable for AGN activity even if galaxies are in pairs. These results can be explained through models of gas dynamics in which pair interactions stimulate the transfer of gas to the nucleus and clusters suppress gas availability for accretion onto the central black hole.

Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription Paper
Steinhardt, Charles L.0000-0003-3780-6801
Silverman, John D.0000-0002-0000-6977
Ellison, Sara L.0000-0002-1768-1899
Additional Information:Draft version October 2, 2014. We thank the anonymous referee for constructive comments. We also thank Surhud More, Steve Bickerton, Claire Lackner, Brian Feldstein, Josh Speagle, and Lisa Kewley for helpful discussions. In addition, ETK is particularly grateful to Richard Ellis for guidance throughout the research project and during the writing process. ETK warmly thanks CLS and JDS for their invaluable mentoring, as well as SLE, JTM, and DRP for their support. Furthermore, the Kavli Institute for the Physics and Mathematics of the Universe and the California Institute of Technology with its Summer Undergraduate Research Fellowships (SURF) program provided key financial and organizational assistance.
Funding AgencyGrant Number
Kavli Institute for the Physics and Mathematics of the UniverseUNSPECIFIED
Caltech Summer Undergraduate Research Fellowship (SURF)UNSPECIFIED
Record Number:CaltechAUTHORS:20141015-145150442
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:50423
Deposited By: Ruth Sustaita
Deposited On:15 Oct 2014 22:17
Last Modified:03 Oct 2019 07:23

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