THE IMPACT OF GALAXY INTERACTIONS ON ACTIVE GALACTIC NUCLEUS ACTIVITY IN zCOSMOS

Journal Article · Fri Dec 09 23:00:00 EST 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/743/1/2· OSTI ID:22004577

Silverman, J D ^[1]; Kampczyk, P; Lilly, S J; Carollo, C M ^[2]; Jahnke, K; Andrae, R ^[3]; Elvis, M; Civano, F ^[4]; Mainieri, V ^[5]; Vignali, C ^[6]; Zamorani, G; Nair, P; Bardelli, S; Bolzonella, M; Cappi, A ^[7]; Le Fevre, O ^[8]; De Ravel, L ^[9]; Bongiorno, A ^[10]; Caputi, K ^[11]; Contini, T ^[12] ; others, and

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1. Institute for the Physics and Mathematics of the Universe (IPMU), University of Tokyo, Kashiwa-shi, Chiba 277-8568 (Japan)
2. Institute of Astronomy, ETH Zuerich, CH-8093 Zuerich (Switzerland)
3. Max-Planck-Institut fuer Astronomie, D-69117 Heidelberg (Germany)
4. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)
5. European Southern Observatory, Garching D-85748 (Germany)
6. Dipartimento di Astronomia, Universita di Bologna, I-40127 Bologna (Italy)
7. INAF Osservatorio Astronomico di Bologna, I-40127 Bologna (Italy)
8. Laboratoire d'Astrophysique de Marseille, Marseille (France)
9. Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh EH9 3HJ (United Kingdom)
10. Max-Planck-Institut fuer extraterrestrische Physik, D-84571 Garching (Germany)
11. SUPA, Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh EH9 3HJ (United Kingdom)
12. IRAP, Universit de Toulouse, UPS-OMP, Toulouse (France)

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{sub *} > 2.5 Multiplication-Sign 10{sup 10} M{sub Sun }) 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{sub 0.5-10keV} > 2 Multiplication-Sign 10{sup 42} erg s{sup -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{sup -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{sup +8.4}{sub -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 {approx}80% that may include late-stage mergers.

• OSTI ID: 22004577
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 743; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
BLACK HOLES
CATALOGS
COMPUTERIZED SIMULATION
GALACTIC EVOLUTION
LUMINOSITY
QUASARS
RED SHIFT
STARS
X-RAY GALAXIES