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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 607172.0, MPI für Astronomie / Publikationen_mpia
The impact of galaxy interactions on active galactic nucleus activity in zCOSMOS
Authors:Silverman, J. D.; Kampczyk, P.; Jahnke, K.; Andrae, R.; Lilly, S. J.; Elvis, M.; Civano, F.; Mainieri, V.; Vignali, C.; Zamorani, G.; Nair, P.; Le Fèvre, O.; de Ravel, L.; Bardelli, S.; Bongiorno, A.; Bolzonella, M.; Cappi, A.; Caputi, K.; Carollo, C. M.; Contini, T.; Coppa, G.; Cucciati, O.; de la Torre, S.; Franzetti, P.; Garilli, B.; Halliday, C.; Hasinger, G.; Iovino, A.; Knobel, C.; Koekemoer, A. M.; Kovač, K.; Lamareille, F.; Le Borgne, J. F.; Le Brun, V.; Maier, C.; Mignoli, M.; Pello, R.; Pérez-Montero, E.; Ricciardelli, E.; Peng, Y.; Scodeggio, M.; Tanaka, M.; Tasca, L.; Tresse, L.; Vergani, D.; Zucca, E.; Brusa, M.; Cappelluti, N.; Comastri, A.; Finoguenov, A.; Fu, H.; Gilli, R.; Hao, H.; Ho, L. C.; Salvato, M.
Date of Publication (YYYY-MM-DD):2011
Journal Abbrev.:The Astrophysical Journal
Issue / Number:1
Audience:Not Specified
Abstract / Description:Close encounters between galaxies are expected to be a viable mechanism, as predicted by numerical simulations, by which accretion onto supermassive black holes can be initiated. To test this scenario, we construct a sample of 562 galaxies (M * > 2.5 × 1010 M ☉) in kinematic pairs over the redshift range 0.25 < z < 1.05 that are more likely to be interacting than a well-matched control sample of 2726 galaxies not identified as being in a pair, both from the zCOSMOS 20k spectroscopic catalog. Galaxies that harbor an active galactic nucleus (AGN) are identified on the basis of their X-ray emission (L 0.5-10 keV > 2 × 1042 erg s–1) detected by Chandra. We find a higher fraction of an AGN in galaxies in pairs relative to isolated galaxies of similar stellar mass. Our result is primarily due to an enhancement of AGN activity, by a factor of 1.9 (observed) and 2.6 (intrinsic), for galaxies in pairs of projected separation less than 75 kpc and line-of-sight velocity offset less than 500 km s–1. This study demonstrates that close kinematic pairs are conducive environments for black hole growth, either indicating a causal physical connection or an inherent relation, such as, to enhanced star formation. In the Appendix, we describe a method for estimating the intrinsic fractions of galaxies (either in pairs or the field) hosting an AGN with confidence intervals, and an excess fraction in pairs. We estimate that 17.8+8.4 –7.4% of all moderate-luminosity AGN activity takes place within galaxies undergoing early stages of interaction that leaves open the question as to what physical processes are responsible for fueling the remaining ~80% that may include late-stage mergers.
Free Keywords:galaxies: active; galaxies: interactions; quasars: general; X-rays: galaxies
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
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